Accessible Gardening

Designing raised beds with appropriate height and accessibility features to accommodate individuals with physical limitations, making gardening more inclusive.


The gradual process of introducing plants to new environmental conditions, such as transitioning them from indoors to outdoors.

ADP (Adenosine Diphosphate)

ADP is the lower-energy form of ATP. It consists of an adenine base, a ribose sugar, and two phosphate groups. When energy is needed, ADP can be converted back to ATP by adding a phosphate group, a process that requires energy input. This conversion often happens during cellular respiration in mitochondria or during photosynthesis in chloroplasts.

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Adventitious Roots

Roots that develop from non-root plant parts, such as stems or leaves, often providing additional anchoring and support.

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The process of introducing air to the nutrient solution to provide oxygen to plant roots and prevent root suffocation.

Aerial Root

An aerial root is a type of root that develops above the ground, typically originating from a stem or branch. Aerial roots can provide support, attachment, and moisture absorption for the plant. They are often found in epiphytic plants that grow on other surfaces like trees or rocks.

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Aerobic Composting

Composting that occurs in the presence of oxygen, creating heat and facilitating rapid decomposition through the activity of aerobic organisms.


A hydroponic system where plant roots are suspended in the air and regularly misted with a nutrient solution to provide moisture and nutrients.


Aerotropism is the response of plants to air or oxygen levels. It can influence the direction of root growth in relation to air pockets or oxygen-rich areas.

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Air Layering

Air layering is a propagation method where a portion of a plant stem is partially wounded and then covered with a moist medium or wrapping. This encourages the development of roots on the stem while it is still attached to the parent plant. Once roots have formed, the rooted portion can be cut and planted as a new individual plant.


Allelopathy is a biological phenomenon in which certain plants release chemicals called allelochemicals into the environment. These chemicals can affect the growth, development, and germination of other nearby plants, either promoting or inhibiting their growth. It is a form of chemical interference that plays a role in plant competition and ecosystem dynamics.

Anaerobic Composting

Composting that occurs in the absence of oxygen, resulting in a slower decomposition process and often producing a less desirable end product.


A flowering plant that completes its entire life cycle, from germination to seed production, within a single growing season.


The part of the stamen where pollen grains are produced; the male reproductive structure of a flower.


A group of fungal diseases causing dark lesions on leaves, stems, and fruits, often leading to defoliation and reduced plant health.


Social insects that can farm aphids and protect them from predators; they also disrupt soil and roots.


Small, soft-bodied insects that suck plant juices, often found on new growth; they can reproduce rapidly.

Apical Dominance

The phenomenon where the terminal bud (apical meristem) at the top of a plant suppresses the growth of lateral buds, directing growth upward.

Apple Scab

A fungal disease affecting apple and pear trees, causing dark scabs or lesions on leaves, fruits, and twigs.


A symbiotic system that combines hydroponics and aquaculture, where fish waste provides nutrients for plant growth, and plants help filter the water for the fish.

Aroid Plants

Plants from the Araceae family, often characterized by unique foliage, such as the large leaves of elephant ears or philodendrons.

Asexual Reproduction

The process of generating new individuals from a single parent without involving the fusion of gametes (reproductive cells). Asexual reproduction in plants often includes methods such as cuttings, division, runners, bulbs, and rhizomes. It results in offspring that are genetically identical to the parent plant.

ATP (Adenosine Triphosphate)

ATP is a high-energy molecule that stores energy in its phosphate bonds. It consists of an adenine base, a ribose sugar, and three phosphate groups. When one phosphate group is removed—usually through a reaction catalyzed by an enzyme—the molecule is converted to ADP (Adenosine Diphosphate), and energy is released. This energy is used to power various cellular functions, including muscle contraction, ion transport, and chemical synthesis.

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Auxins are a group of plant hormones responsible for various aspects of plant growth and development, including cell elongation, apical dominance, root formation, and fruit development. Auxins regulate phototropism and gravitropism by influencing the growth of cells on different sides of plant organs in response to light and gravity.


The angle between a leaf petiole and the stem, where buds or branches can emerge, often leading to new growth or flowering.

Bacterial Canker

Bacterial infections causing cankers or sunken lesions on stems, branches, and fruits; can lead to dieback and plant decline.

Balanced Fertilizer

Fertilizer containing all three primary nutrients (N-P-K) in approximately equal proportions, suitable for general plant feeding.

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Bare Root

A plant or plan division not in a field or container, generally with the soil removed from its roots.

Beneficial Insects

Insects that play a positive role in gardens by pollinating plants, preying on pest insects, or aiding in decomposition.


A plant that completes its life cycle in two growing seasons, typically flowering and setting seeds in the second year of growth.


Materials that can be broken down naturally by microorganisms, reducing environmental impact.

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The variety and richness of different plant and animal species within a given ecosystem, contributing to its health, stability, and resilience.

Biological Nitrogen Fixation (BNF)

A process by which nitrogen gas (N2) from the atmosphere is converted into ammonia (NH3) by certain bacteria. The most common and agriculturally significant form of BNF occurs in the root nodules of leguminous plants, where symbiotic bacteria, primarily from the genus Rhizobium, form a mutualistic relationship with the host plant. Through this partnership, the plant supplies carbon to the bacteria, and the bacteria convert atmospheric nitrogen, which plants cannot use, into a form they can utilize for growth. This natural fertilization process is critical for soil fertility and reduces the need for chemical nitrogen fertilizers.

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Avian pests that peck at fruits, seeds, and young plants, potentially causing crop loss and plant damage.


The flat, expanded portion of a leaf that performs photosynthesis and gas exchange; its shape and size vary among different plant species.


A rapid and severe disease causing wilting, browning, and death of leaves or stems; common types include early and late blight.


A single flower or the collection of flowers on a plant, especially when in full, open display.


A term commonly used to refer to a single flower or the collection of flowers on a plant, especially when in full bloom.

Bokashi Composting

A Japanese composting method that uses a specialized bran inoculated with beneficial microorganisms to ferment and break down kitchen waste.


The premature flowering and production of seed stalks in plants, often caused by stressors such as high temperatures or long day lengths.


Botrytis cinerea, commonly known as gray mold, is a fungal pathogen that affects a wide range of plants. It causes grayish fungal growth on plant parts, including flowers, fruits, leaves, and stems, especially in humid conditions. Botrytis infections can lead to rot, decay, and reduced plant health. Proper ventilation and sanitation practices are important in managing and preventing Botrytis outbreaks.

Botrytis Blight

Also known as gray mold, it causes a grayish fungal growth on plant parts, affecting flowers, fruits, and vegetables in humid conditions.


A modified leaf or leaf-like structure often found just below a flower or an inflorescence, sometimes colorful.


A family of tropical plants with rosette-like leaves and unique structures that collect water, often grown as ornamental houseplants.

Brown Rot

A fungal disease affecting stone fruits like peaches and plums, causing brownish rot on fruits and blossoms, often leading to decay.


An underground storage structure of a flowering plant that contains the embryonic shoot (growing point) and stored nutrients.


A small, bulb-like structure that forms in the leaf axils or flower stalks of some plants. Bulbils can grow into new plants when they fall to the ground or are intentionally planted. They serve as a form of asexual reproduction and are commonly found in plants like onions, garlic, and some lilies.

Cabbage Worms

Caterpillars that attack cabbage-family plants, causing holes in leaves and affecting crop quality.


The collective term for all the sepals of a flower, often forming a protective covering for the developing bud.

Candlepower (Candela)

Candlepower, also known as "candela," is a unit of measurement that quantifies the luminous intensity of a light source in a specific direction. It represents the amount of light emitted by a standard candle at a specified distance and is used to describe the brightness or intensity of a light beam or source.


The uppermost layer of vegetation in a rainforest or tropical environment, consisting of the tallest trees and abundant foliage.

Carbon Sequestration

The process by which plants capture and store carbon dioxide from the atmosphere, helping mitigate climate change by reducing greenhouse gases.

Carbon Sink

Compost serves as a carbon sink, helping to sequester carbon dioxide from the atmosphere and contribute to reducing greenhouse gas emissions.

Carbon-Nitrogen Ratio

The balance between carbon-rich "browns" (e.g., leaves, straw) and nitrogen-rich "greens" (e.g., kitchen scraps, grass clippings) in compost.


Larval stage of moths and butterflies, which can damage plants by eating leaves, stems, and flowers.

Cation Exchange

The process by which positively charged nutrient ions (cations) are released and taken up by plant roots in exchange for other ions.

Ceramic Metal Halide (CMH) Grow Lights

CMH lights combine the spectrum benefits of both MH and HPS lights, but offer a more balanced spectrum, promoting healthy growth throughout the plant's life cycle. CMH lights are known for their efficiency and ability to produce high-quality light.

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Chelated Nutrients

Micronutrients bound to organic molecules to increase their availability and absorption by plants, especially in alkaline soils.

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Chemotropism is the growth or movement of plants in response to chemicals or specific molecules. Plant roots may grow towards or away from chemical gradients.

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Chip on Board (COB)

COB stands for "Chip-on-Board." It refers to a type of LED (light-emitting diode) packaging technology where multiple LED chips are mounted closely together on a single board or substrate. COB LEDs provide high light output, better heat dissipation, and enhanced efficiency, making them popular for horticultural lighting applications.


A condition where plant leaves turn yellow due to a lack of chlorophyll, often indicating nutrient deficiencies or poor soil drainage.

Circulating System

A type of hydroponic setup where nutrient solution is continuously circulated past plant roots, promoting efficient nutrient absorption.

Citrus Canker

A bacterial disease affecting citrus trees, creating raised lesions on leaves, stems, and fruit; can lead to fruit drop and decline.


A disease affecting cruciferous plants like cabbage and broccoli, causing swollen and distorted roots, stunted growth, and yellowing.

CO2 Enrichment

Supplementing carbon dioxide in indoor growing environments to enhance photosynthesis and plant growth.

Coco Coir

A popular growth medium made from coconut husks; it's airy, retains moisture, and has good nutrient-holding capabilities.

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Cold Composting

A slower composting method that relies on natural decomposition without actively managing temperature, suitable for less urgent composting needs.

Cold Frame

A transparent cover placed over the raised bed to create a mini greenhouse, extending the growing season by protecting plants from cold temperatures.

Color Temperature

Color temperature is a characteristic of light that indicates the color appearance of a light source. It is measured in Kelvin (K) and describes whether the light appears warm (lower color temperature) or cool (higher color temperature). In horticultural lighting, color temperature plays a role in influencing plant growth and development.

Colorado Potato Beetles

Insects that attack potato and tomato plants, consuming leaves and defoliating plants if not controlled.


The compression of soil particles, reducing pore spaces and limiting water infiltration, root penetration, and overall soil health.

Companion Planting

The practice of planting compatible crops next to each other within the raised bed, utilizing their beneficial interactions for enhanced growth and pest management.


Decayed organic matter, such as kitchen scraps, yard waste, and leaves, that has undergone a natural decomposition process and is added to soil to improve fertility and structure.

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Compost Activator

An additive (e.g., manure, alfalfa meal) that provides nitrogen and encourages microbial activity, speeding up the composting process.

Compost Bin

A container or structure designed to hold and manage compost materials, providing a controlled environment for the decomposition process.

Compost Pile

A heap or mound of composting materials, often created outdoors, requiring periodic turning and maintenance to facilitate decomposition.

Compost Tea

A liquid fertilizer made by steeping finished compost in water, creating a nutrient-rich solution that can be applied to plants' leaves or roots.

Compost Turner

A tool or equipment designed to efficiently mix and turn compost piles, aiding in the decomposition process and aerating the materials.

Container Gardening

Growing plants in containers, which allows for flexibility in placement, easy management, and the ability to control conditions.


Pruning or cutting back woody plants close to the ground to encourage new growth and maintain a rejuvenated appearance.


A swollen, underground storage organ that resembles a bulb but lacks scales. Corms store nutrients and energy, allowing plants to survive adverse conditions and produce new growth during favorable seasons. They are typically found in plants like gladiolus and crocus.

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A small, miniature corm that forms as a lateral bud on the main corm of certain plants. Cormels can grow into new corm-producing plants when separated and planted, contributing to the propagation of corm-forming species.

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Corn Earworms

Caterpillars that feed on corn, tomatoes, and other crops; they bore into the ears or fruits, affecting quality.


The collective term for all the petals of a flower, usually brightly colored to attract pollinators.


The embryonic leaf within a seed, often serving as a source of nutrients for the emerging seedling until it can establish its own photosynthesis.

CRI (Color Rendering Index)

The Color Rendering Index (CRI) is a quantitative measurement that assesses how accurately a light source renders colors in comparison to a reference light source. It is often expressed on a scale of 0 to 100, with higher values indicating better color rendering. In horticultural lighting, a high CRI is important for accurately assessing plant health and growth.

Crop Rotation

A practice of changing the planting location of different crops each season to prevent soil-borne diseases and maintain soil fertility.


The transfer of pollen from the stamen of one flower to the stigma of a different flower, often involving pollinators.


The area where the stem and roots meet at the base of a plant, often a critical zone for growth and nutrient uptake.


A cultivated variety of a plant species, selected and bred for specific desirable traits like color, size, or disease resistance.

Daily Light Integral (DLI)

The total amount of PAR received by a plant in a 24-hour period, measured in moles of photons per square meter.

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Damping Off

A disease that affects seedlings, causing them to wilt, collapse, and die due to fungal pathogens in the soil.

Dappled Shade

Partial shade created by sunlight filtered through trees or other overhead structures, providing less intense and more diffused light for plants.


The process of removing spent flowers from plants to encourage continued blooming and prevent seed formation.


The natural process of breaking down organic matter into simpler substances through the activity of microorganisms, fungi, and bacteria.

Deep Mulching

A practice of adding a thick layer of organic mulch to the surface of the raised bed, conserving moisture, regulating soil temperature, and suppressing weeds.

Deep Water Culture (DWC)

Deep Water Culture, or DWC, is a hydroponic system where plant roots are submerged in a nutrient solution, often using an air stone for oxygenation.


Large mammals that feed on plants, damaging trees, shrubs, and gardens; they can be challenging to deter.


A period of slowed or suspended growth in plants, often during the colder months, where metabolic activity is reduced to conserve energy.

Downy Mildew

A fungal infection causing yellowish or purplish patches on leaves, along with a downy, grayish growth on the undersides of leaves.

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Drip System

A hydroponic system where nutrient solution is delivered to plant roots in a controlled manner through a network of tubes and drip emitters.

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Ebb and Flow

A hydroponic system where nutrient solution periodically floods the plant roots and then drains away, providing aeration and nutrients.

Ecosystem Services

The benefits that humans receive from natural ecosystems, such as pollination, air purification, and water regulation, supporting life and society.


The material (wood, stone, metal, etc.) used to create a defined border around the raised bed, containing the soil and preventing erosion or soil spillover.

Edible Landscape

A design approach that integrates edible plants (fruits, vegetables, herbs) into ornamental gardens, combining aesthetics with food production.

Electrical Conductivity (EC)

A measure of the nutrient concentration in a solution, indicating its ability to conduct electric current.


The nutritive tissue within a seed that provides nourishment to the developing embryo, often containing starches, oils, or proteins.


The portion of the embryo above the cotyledons that eventually develops into the shoot system of the plant.


A plant that grows on another plant, typically in trees, deriving nutrients from the air, rain, and organic matter accumulated around it.

Erosion Control

Techniques such as planting cover crops, building terraces, or installing retaining walls to prevent or reduce soil erosion.


A training method in which plants are pruned and trained to grow flat against a wall, trellis, or support structure.


Falloff refers to the gradual decrease in light intensity from the center of a light source to its edges or from the source's closest point to its farthest point. In horticultural lighting, understanding falloff is crucial for ensuring even light distribution across plants and avoiding hot spots or shadows.


Supplying essential nutrients to plants through the use of fertilizers, which may need to be tailored to their specific needs.

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Substances added to soil or plants to provide essential nutrients, enhancing plant growth and development.

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Fibrous Roots

Thin, branching roots that spread horizontally near the soil surface, facilitating water and nutrient absorption from a broader area.


The stalk-like structure that supports the anther and holds it above the rest of the flower.

Finished Compost

Compost that has completed the decomposition process and is fully broken down into a stable, nutrient-rich material suitable for use in gardens.

Flea Beetles

Small beetles that chew tiny holes in leaves, affecting crops like tomatoes, eggplants, and potatoes.

Floral Anatomy

The internal structures of a flower, including the stamen, pistil, petals, and sepals, which collectively enable reproduction.


A small flower or flower cluster within an inflorescence, often found in plants like sunflowers or broccoli.

Fluorescent Grow Lights

Fluorescent grow lights come in two main types: compact fluorescent lamps (CFL) and T5 high-output fluorescent tubes.
They emit a balanced spectrum of light suitable for various growth stages, including seedlings, vegetative growth, and flowering.
CFLs are often used for small-scale setups, while T5 tubes are popular for larger indoor gardens.

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Foliar Feeding

The application of liquid fertilizer directly to plant leaves, allowing for rapid nutrient absorption and addressing deficiencies.

Forest Gardening

A sustainable agroecological system that mimics the structure and function of natural forests, integrating diverse edible and useful plants.

Frost Heave

The lifting of soil and plants caused by repeated freezing and thawing cycles, which can expose roots and disrupt plant growth.

Full Spectrum

Full spectrum lights aim to mimic natural sunlight, providing a balanced range of wavelengths for all growth stages.

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Fusarium Wilt

A soilborne fungal disease leading to wilting, yellowing, and eventual death of plants; affects various crops, including tomatoes.

Garden Frame

The structure that holds the raised bed in place, which can be made from various materials such as wood, metal, concrete blocks, or composite materials.

Genetic Diversity

The range of genetic variation within a species, essential for adapting to changing environmental conditions and resisting diseases.


A horticultural technique where a stem or bud of one plant is attached to the rootstock of another to combine desirable traits.


Gravitropism, also known as geotropism, is the response of plants to gravity. Positive gravitropism occurs when plant roots grow downward (with gravity), and negative gravitropism occurs when stems grow upwards (against gravity).

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Green Manure

Crops grown specifically to be incorporated into the soil as organic matter, improving soil structure and nutrient content when they decompose.


A controlled environment designed for plant growth, often using transparent materials to allow sunlight in while keeping out harsh weather conditions.

Grow Light

A grow light is an artificial light source providing plants with the necessary light spectrum and intensity for photosynthesis and optimal growth, especially in indoor environments where sunlight may be limited. Grow lights are a crucial tool for indoor gardening, hydroponics, and other controlled growing setups.

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Grow Tent

An enclosed structure made of fabric or material with reflective interiors, designed to create a controlled indoor growing environment.

Growth Medium

The material in which plant roots grow, can be soilless (like coco coir) or soil-based, depending on the hydroponic method used.

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A grouping of companion plants grown together to benefit each other through mutual support, nutrient sharing, and pest deterrence.

Harden Bulb

The process of exposing bulbs to colder temperatures to stimulate flower bud formation, commonly used for spring-flowering bulbs.

Hardening Off

Gradually acclimating indoor-grown plants to outdoor conditions by exposing them to increasing amounts of sunlight, wind, and temperature fluctuations.

Hardiness Zone

A geographical area defined by its average annual minimum temperature, helping to determine which tropical plants can thrive in a location.


Non-plant elements of a garden, such as paths, fences, walls, and patios, that contribute to the overall design.

High-Intensity Discharge (HID) Grow Lights

HID lights include Metal Halide (MH) and High-Pressure Sodium (HPS) lamps.
MH lights emit blue-heavy light, ideal for vegetative growth, while HPS lights emit red-orange light, suitable for flowering.
HID lights are powerful and widely used for larger indoor gardens but can generate significant heat and require proper ventilation.

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Horticultural Therapy

The use of gardening activities to promote physical, emotional, and psychological well-being and rehabilitation for individuals with various needs.

Hot Composting

A composting method that generates high temperatures (130-160°F or 54-71°C) through microbial activity, accelerating the decomposition process.

Hot Spot

A "hot spot" refers to an area under a grow light where the light intensity is significantly higher than in surrounding areas. This concentrated light can potentially lead to uneven light distribution and may cause plant stress or damage if not properly managed.

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A gardening technique that involves burying logs, branches, and organic matter beneath the soil surface to supposedly improve water retention and nutrient availability.


The amount of moisture present in the air, a crucial factor for tropical plants that often thrive in high humidity environments.


Dark, organic material formed from the decomposition of plant and animal matter in the soil, enhancing soil fertility and structure.


A plant variety created by crossbreeding two different parent plants to achieve specific traits, such as disease resistance or increased yield.


A subset of hydroponics where plants are grown in an inert substrate while the roots are continuously submerged in a nutrient solution.

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Hydrotropism is the growth or movement of plant roots in response to water. Positive hydrotropism leads roots to grow towards a water source.

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A device used to measure humidity levels in the growing environment; maintaining appropriate humidity is important for plant health.


The part of the embryo between the cotyledons and the radicle (embryonic root), often responsible for pushing the seedling above the soil surface.

Indigenous Knowledge

Traditional knowledge and practices passed down through generations by indigenous communities, often related to local plant uses and cultivation.

Indigenous Plants

Native plants that naturally occur in a specific region and have coevolved with local ecosystems, requiring minimal care and maintenance.

Indoor Gardening

The practice of growing plants indoors, often using controlled environments and specialized equipment.

Indoor Tropical Plants

Tropical plants that are commonly grown indoors, often in pots or containers, to mimic their natural habitat and climate conditions.


A cluster or arrangement of flowers on a single stem, varying in shapes like spikes, umbels, racemes, or panicles.

Inorganic Fertilizer

Fertilizer composed of synthetic compounds, often with specific nutrient ratios, allowing precise nutrient supplementation.

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Intensive Gardening

A gardening approach that maximizes the use of available space, often through techniques like raised beds, vertical gardening, and close plant spacing.


The segment of stem between two adjacent nodes, often elongating to promote distance between leaves or branching points.

Invasive Species

Non-native plants that spread aggressively and can negatively impact local ecosystems by outcompeting native species.

IR (Infrared)

IR (Infrared) is a type of electromagnetic radiation with wavelengths longer than visible light. In horticultural lighting, IR light is sometimes used to promote plant growth and flowering by providing additional energy for photosynthesis and other metabolic processes.

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Japanese Beetles

Metallic-green beetles that chew on leaves, flowers, and fruit; their feeding can cause skeletonized leaves.

Jump Starting

Using techniques like pre-sprouting or starting seeds indoors to give plants a head start before transferring them to the outdoor garden.

Juvenile Growth

The early stages of plant growth, from germination to maturity, characterized by rapid cell division, leaf formation, and establishment.

Kelp Fertilizer

A type of organic fertilizer derived from kelp seaweed, rich in trace minerals, nutrients, and growth-promoting hormones.

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Keyhole Garden

A circular raised bed with a small notch or opening, resembling a keyhole, allowing easy access to the center of the bed for planting, watering, and care.

Kneeling Pad

A cushioned pad or mat used by gardeners to protect knees from strain and discomfort while kneeling or working close to the ground.

Lateral Shoot

A side branch or offshoot that grows from the main stem of a plant, contributing to its overall structure and branching pattern.


The loss of nutrients from the soil due to excessive water drainage, often resulting in nutrient runoff and reduced soil fertility.

Leaf Miners

Larvae that tunnel through leaves, causing squiggly trails and discolored patches; they affect leaf appearance.

Leaf Spot

Fungal or bacterial infections that create spots or lesions on leaves, varying in color and shape; can affect plant health and yield.


Small insects that suck plant sap, leading to stippling, yellowing, and curling of leaves; they can transmit diseases.

LED Grow Light

Light-Emitting Diode (LED) grow lights have gained popularity due to their energy efficiency and customizable spectrum.
LEDs allow growers to fine-tune the light spectrum for specific plant needs, promoting efficient photosynthesis.
They produce less heat, reducing the need for excessive cooling and ventilation, and are available in various shapes and sizes.

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Light Bleaching

Light bleaching occurs when plants are exposed to excessive light intensity, often resulting in the fading or discoloration of leaves. This can happen due to overly intense or prolonged exposure to artificial or natural light sources, causing stress and potential damage to plant tissues.

Light Requirements

The specific amount and quality of light needed by plants for healthy growth, often varying based on their natural habitats.


A soil type with a balanced mixture of sand, silt, and clay particles, often considered ideal for plant growth due to good drainage and fertility.


A lumen stands as a quantifier for the brightness of light emitted. A solitary lumen corresponds to the radiance produced by a lone candle on a square foot area, positioned precisely one foot away from the candle. It's less relevant for plants because the measurement of lumens is tailored to the human visual system and how humans perceive light.

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A unit of measurement for illuminance, indicating the amount of light falling on a surface; not as precise for plants as PPFD because lux is a unit of measurement that quantifies illuminance, which is the amount of visible light (including all wavelengths) that falls on a surface. Lux is calibrated to the sensitivity of the human eye and how humans perceive light, rather than being tailored to the specific light wavelengths that plants use for photosynthesis and other physiological processes.

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Essential nutrients required by plants in relatively large amounts, including nitrogen, phosphorus, and potassium (N-P-K).

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The edge of a leaf, often with various shapes (e.g., serrated, lobed) that contribute to the leaf's overall appearance and function.


Soft-bodied insects that cluster on plant parts, sucking sap and excreting honeydew, often attracting ants.

Mel Bartholomew

The developer of the "Square Foot Gardening" method, emphasizing small, organized planting areas, precise spacing, and efficient use of resources.


Undifferentiated plant tissue responsible for growth and development; apical meristems are found at the tips of stems and roots.


The localized climate conditions within a small area, influenced by factors like sunlight, wind, and landscape features, impacting plant growth.

Micronutrient Deficiency

A condition where plants lack essential trace minerals, such as iron, zinc, or copper, leading to poor growth and development.


Essential nutrients required by plants in smaller quantities, such as iron, manganese, zinc, and copper.

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The central vein that runs down the center of a leaf, connecting the leaf base to the tip and providing structural support.


A protective layer of organic or inorganic material (such as straw, wood chips, or plastic) placed over the soil surface to conserve moisture, suppress weeds, and improve soil health.

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Mulch Volcano

An improper practice of piling mulch around the base of a tree in a cone shape, which can lead to moisture retention, root rot, and other issues.


Applying a layer of mulch to the soil surface to conserve moisture, control weeds, and regulate soil temperature.

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N-P-K Ratio

The ratio of nitrogen (N), phosphorus (P), and potassium (K) in a fertilizer, indicating the relative proportion of these nutrients.

NADPH (Nicotinamide Adenine Dinucleotide Phosphate)

NADPH is a coenzyme that serves as an electron carrier. It is mainly produced during the light-dependent reactions of photosynthesis in plants but also plays a role in other cellular processes like lipid and nucleic acid synthesis. NADPH provides the high-energy electrons required to convert carbon dioxide into glucose in the Calvin Cycle. It is the reduced form of NADP+ and carries electrons as well as a hydrogen ion (H+), ready to donate these to other molecules in biochemical reactions.

Native Plants

Plant species that naturally occur in a specific region and have adapted to its climate, soil, and other conditions.

Natural Pest Control

The use of natural predators, parasitoids, and beneficial insects to manage pest populations and reduce the need for chemical interventions.


A sugary liquid produced by flowers to attract pollinators like bees, butterflies, and birds for effective pollination.

Net Pot

A container with an open mesh design that holds the plant in place while allowing the roots to grow through and access the nutrient solution.

NIR (Near-Infrared)

NIR (Near-Infrared) light is a type of electromagnetic radiation with wavelengths slightly longer than visible light. In horticultural lighting, NIR light is sometimes used to enhance certain plant processes, including photosynthesis and nutrient uptake. It can also provide valuable information for monitoring plant health and stress levels.

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Nitrogen (N)

A macronutrient crucial for plant growth, used for foliage development, protein synthesis, and overall plant vigor.

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The point on a stem where leaves, branches, or flowers arise; nodes are crucial for growth and branching patterns.

Non-Toxic Pest Control

The use of natural, non-harmful methods to manage pests, including physical barriers, companion planting, and biological controls.

NPK Ratio

The three main elements in fertilizers represented by their chemical symbols: Nitrogen (N), Phosphorus (P), and Potassium (K), indicating their proportions.

Nutrient Cycling

The natural process of nutrient movement and recycling within an ecosystem, involving decomposition, absorption, and release by plants.

Nutrient Film Technique (NFT)

Nutrient Film Technique, or NFT, is a hydroponic system where a thin film of nutrient solution flows over plant roots, providing oxygen and nutrients.

Nutrient Leaching

The movement of nutrients (e.g., nitrogen, potassium) through soil due to excessive water, potentially leading to nutrient loss and imbalance.

Nutrient Solution

A mixture of water and essential nutrients that provides plants with the necessary elements for growth in hydroponic systems.

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Nutrient Toxicity

Excessive levels of a specific nutrient that can harm plant growth and health, often causing burning or stunted development.

Nutrient Uptake

The process by which plant roots absorb nutrients from the soil and transport them to various plant tissues for growth and function.


Plant varieties that are pollinated by natural mechanisms, resulting in offspring with similar traits to the parent plant.


The cultivation of fruit-bearing trees (orchard trees) in a systematic and planned manner to optimize fruit production and health.


A diverse and popular group of flowering plants with intricate blooms, often requiring specific care due to their unique growth habits.

Organic Fertilizer

Fertilizer derived from natural sources like compost, manure, bone meal, or plant matter, enriching soil with organic matter.

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Organic Gardening

A method of gardening that emphasizes the use of natural, sustainable practices and materials while avoiding synthetic chemicals and pesticides.

Organic Matter

Decomposed or decaying plant and animal materials, such as compost, manure, and leaf litter, that enrich soil fertility and structure.


The movement of water through plant cell membranes from areas of low solute concentration to areas of high solute concentration.


The enlarged base of the pistil that contains the ovules, which develop into seeds after successful fertilization.


Protecting plants from cold temperatures during the winter months, often involving bringing them indoors or providing shelter.

Pallet Garden

A raised bed made from a repurposed wooden pallet, often filled with soil and used for vertical gardening, suitable for growing herbs, flowers, or small crops.

PAR (Photosynthetically Active Radiation)

The spectrum of light wavelengths (400-700 nm) that plants use for photosynthesis.


A type of fruit development where fruit forms without fertilization, often leading to seedless fruits (e.g., seedless grapes).


The small stalk that supports an individual flower in an inflorescence or cluster.


The stalk that supports a single flower or a cluster of flowers, arising from the stem or branch.

Percolation Rate

The speed at which water moves through soil, influencing drainage and the ability of plants to access water and nutrients.


A type of flowering plant that lives for multiple years, often regrowing and flowering annually after a dormant period.


The collective term for both the petals and sepals of a flower, especially when they look similar in appearance.


An ecological design approach that seeks to create sustainable and self-sufficient systems by mimicking natural ecosystems.

Pest Threshold

The population level of pests at which intervention measures, such as pesticide application, become necessary to prevent significant damage.

Pests and Diseases

Common challenges faced by tropical plants, including insect pests and diseases that can be managed through proper care and prevention.


The colorful, often delicate part of a flower that attracts pollinators and provides protection for reproductive structures.


The slender stalk that attaches a leaf to the stem, allowing movement and positioning of the leaf for optimal light exposure.


A scale that measures the acidity or alkalinity of a nutrient solution; affects nutrient availability for plant roots.

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pH Buffer

Substances used to maintain a stable pH level in the nutrient solution, preventing rapid shifts in acidity or alkalinity.

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pH Range

The acceptable range of pH values for a nutrient solution, within which plant roots can optimally absorb nutrients.

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The vascular tissue in plants responsible for transporting sugars, nutrients, and other organic compounds produced through photosynthesis from the leaves to other parts of the plant. Phloem consists of sieve tube elements and companion cells, forming a network of tubes that support the distribution of essential nutrients throughout the plant.

Phosphorus (P)

A macronutrient important for root development, flowering, and fruiting, playing a role in energy transfer within plants.


The duration of light exposure a plant receives in a 24-hour period, influencing flowering, growth, and various physiological processes.

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Photosynthesis is the biological process through which plants, algae, and some bacteria convert light energy into chemical energy by using sunlight, carbon dioxide, and water. This energy is stored in glucose and other organic compounds, supporting the growth and development of the organism. Oxygen is released as a byproduct during photosynthesis.


Phototropism is the directional growth of plants in response to light. Positive phototropism causes plant parts to bend towards a light source, while negative phototropism (or skototropism) is growth away from light.

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Phytophthora Root Rot

A soilborne water mold causing root rot, wilting, and eventual plant death; commonly affects trees, shrubs, and ornamental plants.

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The female reproductive part of a flower, comprising the stigma, style, and ovary where seeds develop after fertilization.

Plant Succession

The gradual and natural process of changing plant communities over time in response to environmental conditions, often following disturbances.

Plant Training

Techniques such as topping, pruning, and tying to shape and manipulate plant growth for higher yields and better light exposure.


A small, immature plant that develops from a parent plant and has the potential to grow into a full-sized plant. Plantlets often form as offshoots, runners, or in the case of some bulbous plants, and can be separated and planted to establish new individual plants.

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The embryonic shoot within a seed that gives rise to the stem and leaves of the plant upon germination.


The fine, powdery grains produced by the anther; it contains the male gametes and is essential for fertilization.


The transfer of pollen from the stamen to the stigma, enabling fertilization and the production of seeds and fruit.


An animal (insect, bird, bat) that carries pollen from one flower to another, facilitating pollination and reproduction.

Potassium (K)

A macronutrient vital for overall plant health, water regulation, disease resistance, and enzyme activation.

Potting Mix

The specialized soil blend used for potted plants, designed to provide adequate drainage, aeration, and nutrient retention.

Powdery Mildew

A fungal disease that appears as white powdery spots on leaves and stems, often causing stunted growth and reduced plant vigor.

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PPF (Photosynthetic Photon Flux)

The total amount of PAR emitted by a light source per unit of time, measured in micromoles per second (μmol/s).

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PPFD (Photosynthetic Photon Flux Density)

Photosynthetic Photon Flux Density (PPFD) is a measurement that quantifies the amount of photosynthetically active photons (light) reaching a specific area per unit of time. It is expressed in micromoles of photons per square meter per second (μmol/m²/s) and is a crucial metric for assessing the light intensity available for plant photosynthesis and growth.

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The process of growing new plants from seeds, cuttings, or other plant parts.


The practice of selectively removing parts of plants, such as dead or overgrown branches, to promote healthy growth and shape.

Quantum Board Lights

Quantum board LED lights are a newer type of LED technology, featuring multiple LED chips mounted on a board. They provide even light distribution and excellent coverage, often with a broader spectrum.
Quantum board lights are energy-efficient and offer good performance for a variety of plant growth stages.

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A type of calcium-rich material used to increase soil pH and provide nutrients, though it should be used cautiously due to its alkalinity.


A temporary state of inactivity or dormancy in plants, often triggered by environmental stressors, before resuming normal growth.


Herbivorous mammals that feed on plants, causing damage to vegetables, flowers, and ornamental plants.


The embryonic root of a seed that develops into the primary root of the plant upon germination.


A dense, diverse ecosystem characterized by high rainfall, humidity, and lush vegetation, often where many tropical plants originate.

Raised Bed

A garden bed that is elevated above the ground level, often contained within a frame or structure, providing improved drainage, soil management, and plant access.

Raised Bed Liner

A material (plastic, geotextile fabric) placed at the bottom of the raised bed to separate the soil from the ground, preventing weed growth and soil contact.


The tip of the flower stalk where all the flower parts are attached, including the whorls of sepals, petals, etc.


A container holding the nutrient solution in a hydroponic system, from which the solution is pumped or circulated to the plants.


A modified stem that grows horizontally below or partially above the soil surface, sending out shoots and roots to create new plants.


The region of soil around plant roots where microbial activity, nutrient exchange, and interactions between roots and soil occur.


A mineral-based growth medium made from melted rock, often used for starting seeds and providing mechanical support to plants.

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Animals like mice, rats, and voles that eat plants, roots, and fruits; they can damage crops and gardens.

Root Hair

Tiny, hair-like structures on plant roots that increase the surface area for nutrient and water absorption from the soil.

Root Rot

A fungal disease that affects plant roots in overly wet conditions, commonly controlled by maintaining proper aeration and drainage.

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Root Zone

The area around plant roots where nutrient uptake occurs; maintaining a healthy root zone is crucial for overall plant health.


A condition where plant roots become crowded and encircle the root ball, leading to restricted growth and reduced nutrient uptake.


A long, trailing stem that grows horizontally along the ground and produces new plantlets or roots at its nodes. Runners enable asexual reproduction by allowing new plants to grow from the parent plant, as seen in strawberry plants and certain ground covers.

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The excess nutrient solution that drains out of a growing medium, carrying away excess salts and preventing nutrient buildup.

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Fungal infections resulting in reddish, yellowish, or brownish spots on leaves, often accompanied by powdery or rust-colored growth.

Scale Insects

Tiny insects that attach to plant stems and leaves, sucking sap; they appear as small, immobile bumps.

Season Extension

Techniques like cold frames, row covers, or cloches used in raised bed gardening to prolong the growing season and protect plants from frost and cold.

Secondary Nutrients

Nutrients required by plants in moderate amounts: calcium (Ca), magnesium (Mg), and sulfur (S), often found in secondary fertilizers.

Seed Coat

The outer protective covering of a seed, often made of one or more layers, which shields the embryo from damage and desiccation.


A young, developing plant that has germinated from a seed and is in its early stages of growth, typically after the cotyledons have emerged.


The transfer of pollen from the stamen to the stigma within the same flower or from one flower on the same plant to another.

Self-Watering Pot

A container designed with a reservoir that allows plants to draw water as needed through capillary action or a wicking system, reducing the frequency of manual watering and helping to maintain consistent moisture levels.

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Self-Watering System

An irrigation setup integrated into the raised bed design, using a reservoir or wicking system to provide a consistent supply of water to plants.

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The leaf-like structure that encloses and protects the flower bud before it opens; part of the outermost whorl of a flower.

Sheet Composting

A method of composting where organic materials are spread directly on the soil surface, allowing decomposition to occur gradually over time.

Showy Flowers

Flowers with vibrant colors, distinct patterns, and conspicuous features that attract pollinators and human attention.


The deposition of fine soil particles in water bodies due to erosion or human activity, leading to sediment buildup and water quality issues.

Slow-Release Fertilizer

Fertilizer that releases nutrients gradually over time, providing a consistent source of nutrition to plants over an extended period.

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Slugs and Snails

Soft-bodied mollusks that feed on plants, leaving irregular holes in leaves and causing seedling damage.

Soil Aeration

The presence of air pockets within the soil, crucial for oxygen availability to plant roots, microbial activity, and overall soil health.

Soil Amendments

Materials like compost, manure, lime, and sulfur added to soil to improve its physical structure, nutrient content, and overall quality.

Soil Compaction

The compression of soil particles due to factors like foot traffic, machinery, or heavy rainfall, reducing pore spaces and limiting root growth.

Soil Drainage

The movement of excess water from the soil, crucial for preventing waterlogged conditions and promoting healthy root growth.

Soil Erosion

The natural process of soil displacement due to factors like wind, water, and human activity, which can result in loss of topsoil and reduced fertility.

Soil Fertility

The soil's ability to provide essential nutrients to plants for optimal growth, influenced by organic matter, nutrient content, and pH.

Soil Mix

A customized blend of soil components (e.g., compost, topsoil, vermiculite) used to fill the raised bed, providing optimal drainage, aeration, and nutrient content.

Soil Moisture Meter

A tool used to measure the moisture content of soil, assisting in proper watering and ensuring tropical plants receive adequate hydration.

Soil pH

A measurement of the acidity or alkalinity of soil, influencing nutrient availability to plants; pH levels above 7 are alkaline, and below 7 are acidic.

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Soil Salinity

The concentration of soluble salts in the soil, affecting water uptake by plants and potentially causing physiological stress.

Soil Structure

The arrangement and organization of soil particles into aggregates, affecting water movement, aeration, and root growth in the soil.

Soil Texture

The proportion of sand, silt, and clay particles in soil, determining water-holding capacity, drainage, and aeration characteristics.

Soluble Salts

The minerals left behind after water evaporates from a nutrient solution, which can accumulate and potentially harm plant roots.

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Spectrum-Specific Lights

Spectrum-specific lights (Narrow Spectrum) focus on certain parts of the light spectrum to optimize growth during specific stages, such as blue light for vegetative growth or red light for flowering.

Spider Mites

Tiny arachnids that suck plant sap, leaving stippling and webbing; they thrive in dry and hot conditions.

Square Foot Gardening

An intensive planting method where plants are spaced closely in designated squares or grids within the raised bed, maximizing space and yield efficiency.

Squash Bugs

Insects that feed on sap, affecting plants like squash and pumpkins; they can transmit plant diseases.

Squash Vine Borers

Larvae that tunnel into squash and pumpkin vines, causing wilting and plant death; they're difficult to manage.


The male reproductive part of a flower, consisting of the filament and the anther where pollen is produced.


The sticky, pollen-receptive part of the pistil where pollen grains attach during pollination.


A small, leaf-like structure located at the base of a leaf stalk (petiole), sometimes serving as protection or an additional support.


A horizontal stem or runner that grows along the soil surface and produces new plants at its nodes, facilitating vegetative reproduction.

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The slender tube-like structure that connects the stigma and the ovary, allowing pollen tubes to reach the ovary.


The layer of soil located beneath the topsoil, often less fertile and compacted, affecting drainage and root penetration.


An inert material (such as coconut coir, perlite, LECA, pon, or rockwool) used to support plant roots and hold nutrient solution in hydroponic systems.

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Succession Planting

Planting new crops in the raised bed immediately after harvesting the previous ones, maintaining a continuous supply of fresh produce throughout the growing season.


The growth of shoots or stems emerging from the base of a plant or its roots, often requiring removal to maintain the desired plant form.

T5 Fluorescent

T5 is a type of fluorescent lamp that has a diameter of 5/8 of an inch (approximately 16 mm). It is known for its energy efficiency, high light output, and compact size. T5 lamps are commonly used in horticultural lighting setups due to their ability to provide intense and focused light. Newer LED lights use the term T5 for marketing purposes, but it has no technical relation to T5 Fluorescent lighting.

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T8 Fluorescent

T8 is another type of fluorescent lamp with a diameter of 1 inch (approximately 25 mm). It is widely used in various applications and offers a balance between energy efficiency and light output. T8 lamps are suitable for general indoor gardening and plant growth. The term T8 is also used for marketing purposes but it has no technical alignment with fluorescent lighting.

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A main root that grows vertically downward from the radicle, providing stability and anchoring the plant while also accessing deeper soil layers.


A specialized, slender structure that certain plants produce to twine around supports, aiding in climbing and anchoring the plant.


A term used when the petals and sepals of a flower are similar in appearance and are collectively referred to.

Terminal Cormel

A type of cormel that forms at the tip of a corm or in the place of a spent flower on certain corm-forming plants. Terminal cormels can be removed and planted to propagate new plants, contributing to the expansion of the species.

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Thermotropism is the response of plants to temperature changes. It can involve directional growth towards or away from temperature variations.

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A rapid movement or folding of plant leaves in response to touch or physical contact, often as a defense mechanism against herbivores.


Thigmotropism is the growth or movement of plants in response to touch or contact with a solid object. It enables climbing plants to attach themselves to structures for support.

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The process of removing excess plants from a row or bed to allow the remaining plants more space and resources to grow.


Small, slender insects that feed on plant juices, causing distorted growth and silvery streaks on leaves.


The mechanical manipulation of soil through activities like plowing, cultivating, or tilling, often used to prepare soil for planting.

Tobacco Mosaic Virus

A viral infection causing mosaic patterns and mottled discoloration on leaves, affecting tobacco plants and other crops.

Tomato Yellow Leaf Curl Virus

A viral infection transmitted by whiteflies, causing leaf curling, yellowing, and stunted growth in tomato and pepper plants.


Adding a thin layer of compost, mulch, or other organic material to the soil surface to improve soil structure and provide nutrients.


The uppermost layer of soil, rich in organic matter and nutrients, where most plant roots and microbial activity occur.

Total Dissolved Solids (TDS)

A measurement of the concentration of all dissolved substances in the nutrient solution, including minerals and salts.

Transgenic Plants

Plants that have been genetically modified by inserting genes from other organisms to express specific traits, such as pest resistance.


The process by which plants release water vapour through tiny pores (stomata) on their leaves, helping to draw up water and nutrients from the roots.


The process of moving seedlings or young plants from propagation to the main hydroponic system for further growth.

Trellis or Support

A structure placed within or adjacent to the raised bed to support vining or climbing plants, optimizing space and allowing for better air circulation.

Tropical Plants

Plants native to or adapted to tropical climates, characterized by warmth, high humidity, and year-round growth.


The process of mixing or aerating compost materials to ensure even decomposition, prevent odors, and promote microbial activity.


Planting smaller, shade-tolerant plants beneath larger trees or shrubs to maximize use of garden space and create layered interest.


The layer of vegetation beneath the canopy in an environment, often comprising smaller trees, shrubs, and other plants.

Urban Agriculture

The practice of growing and producing food in urban environments, utilizing small spaces and innovative techniques to foster local food production.

Urban Forestry

The management and care of trees and other vegetation in urban areas to enhance environmental quality, aesthetics, and community well-being.

UV (Ultraviolet)

UV (Ultraviolet) light is a type of electromagnetic radiation with wavelengths shorter than visible light. In horticultural lighting, UV light is sometimes used in specific wavelengths to influence plant growth, development, and defense mechanisms. UV light can affect various plant processes, including phytochemical production and pest resistance.

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The occurrence of differently colored or patterned areas on plant leaves or other plant parts. Variegation is a result of variations in pigmentation, chlorophyll distribution, or cell structure, often creating unique and visually striking foliage patterns.


Composting using worms, typically red wigglers, to break down organic materials into nutrient-rich castings (worm waste) for soil enrichment.

Vertical Farming

Growing plants in stacked layers or vertical racks, maximizing space efficiency in indoor environments.

Verticillium Wilt

A disease caused by soilborne fungi, resulting in wilting, yellowing, and leaf drop; affects a wide range of plants and trees.

Watering Schedule

A planned regimen for irrigating plants based on factors like plant type, weather, soil moisture levels, and water requirements.


Tiny, white insects that feed on plant sap and excrete honeydew, causing leaves to turn yellow and wilt.


The process by which water or other liquids are drawn upward through a material (such as soil) due to capillary action, enabling moisture to move against gravity. Wicking is often used in self-watering systems and certain planters.

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Larvae of click beetles that feed on plant roots and seeds, causing damage to root crops and seedlings.


Landscaping or gardening practice that focuses on water conservation through the use of drought-tolerant plants, efficient irrigation, and soil management.


The vascular tissue in plants responsible for transporting water and dissolved minerals from the roots to the rest of the plant. It consists of several cell types, including vessel elements and tracheids, arranged in tubes that form a network throughout the plant. Xylem also provides structural support to the plant and contributes to its overall rigidity.


The quantity of harvested produce or flowers from a given area or number of plants, often measured in weight or volume.


Micromoles per square meter per second - a unit of measurement for PPFD, indicating the number of photons hitting a surface each second.

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