Tropical Rainforest

Caring for Tropical Rainforest Plants Indoors

Reading Time: 6 - 8 minutes (1703 words)

When you bring a tropical houseplant into your home, you're not just adding a pop of green—you're inviting a small piece of the tropical rainforest into your space. Many of the popular indoor plants us unlikely gardeners buy originate from the understory and lower to mid canopy of tropical rainforests. These jungle environments are perfect training grounds for survival with limited sunlight, making these plants well-suited for life inside our homes. Understanding their natural habitats can help you create a comfortable environment for them in your interior space.

The Layered World of Tropical Rainforests

Tropical Rainforest Layers

Tropical rainforests are like living skyscrapers, divided into distinct layers, each with unique conditions that support different plant life. The canopy and understory are crucial for creating the complex environment that allows rainforest plants to thrive. The canopy, often referred to as nature's umbrella, shields the lower layers from intense sunlight, regulating the amount of light that reaches them. This protection creates a habitat ideal for the understory, where many of our indoor plants originate. For our beloved indoor plants, it’s the lower canopy and understory that matter most, as they provide the filtered light and stable conditions these plants need to flourish.

The Canopy: Nature’s Umbrella

The canopy sits about 20 to 40 meters (65 to 130 feet) above the forest floor, forming a dense cover that absorbs most of the sunlight. This leafy shield not only blocks out the intense tropical sun but also regulates the microclimate below, maintaining humidity and reducing temperature fluctuations. This protection allows only a small amount of diffused light to filter through to the lower layers, creating a perfect environment for shade-loving plants. Many of the indoor plants we cherish today have evolved to thrive in these conditions, making them well-suited for low-light areas in our homes.

The Understory: A Shaded Sanctuary

Beneath the canopy is the understory—an environment that receives just 5% to 15% of the available total sunlight, which translates to approximately 100 to 300 µmol/m²/s in PPFD. This layer plays a critical role in the rainforest ecosystem by providing a unique habitat that supports a wide range of plant and animal species. The understory is characterized by lower light levels compared to the Canopy or Emergent layer, which create a tranquil, shaded environment perfect for shade-tolerant plants. Plants here have adapted to thrive in:

  • Low Light: The canopy's dense coverage filters sunlight into a soft, diffused glow.
  • High Humidity: Minimal air circulation and abundant plant life create a consistently moist environment.
  • Stable Temperatures: The canopy provides natural insulation, keeping temperatures warm and steady year-round.

These plants have evolved broad leaves to capture every bit of available light and efficient photosynthesis to make the most of low-light conditions.

Bringing Rainforest Light Levels Indoors

Understanding how much light these rainforest layers get helps us create suitable conditions for our indoor plants.

Measuring Light for Houseplants

Photosynthetic Photon Flux Density (PPFD) measures the intensity of light in the Photosynthetically Active Radiation (PAR) range, which is what plants use for growth. In a rainforest

  • Emergent Layer: 2,000 - 2,200 µmol/m²/s.
  • Under Canopy: 1,200 - 1,500 μmol/m2/s
  • Upper Canopy: 800 - 1,200 μmol/m2/s
  • Mid Canopy: 500 - 800 μmol/m2/s
  • Lower Canopy: 300 - 500 μmol/m2/s
  • Understory: 100 - 300 µmol/m²/s
  • Forest Floor: < 50 μmol/m2/s

In and around our homes, light conditions can vary almost as widely, but indoors intensity is generally low unless a plant is placed directly in sunlight. Bright, indirect light next to a south-facing window may provide ample intensity, but much of the rest of available light indoors is filtered and/or indirect. This means that for many indoor spaces, light levels can be insufficient for most of our favourite plants without additional help. Most indoor locations receive indirect or low light, making it important to understand the specific lighting needs of your plants to ensure they thrive.

Tips for Mimicking Understory Light Indoors

Diffuse Direct Sunlight: Use sheer curtains, or privacy film to filter bright southern or south western light, creating conditions similar to the understory for most of the day.
Avoid Harsh Sunlight: Direct sunlight can overwhelm understory plants, causing photo-inhibition, damaging chloroplasts, and eventually resulting in leaf burn.
Consistency is Key: Although light in the jungle changes throughout the day, maintaining a steady artificial light prevents light stress from sudden changes.

Adapting Indoor Spaces for Tropical Plants

Creating a rainforest-inspired environment at home involves more than just providing adequate light. It requires attention to humidity and temperature (forming a Vapour Pressure Deficit, or VPD), and soil conditions to fully replicate the nurturing environment of a tropical rainforest. Here's how to make it work:

Light Setup

  • Assess Natural Light: Use a light meter of smart phone app like Photone or PPFD Meter to determine the PPFD in different areas of your home. If using an Android device you will need the Uni-T Lux meter to pair with your phone to provide accurate measurements with the apps.
  • Artificial Lights: Use good quality LED grow lights like Sansi or ViparSpectra, with full-spectrum capabilities to boost natural light.
  • Light Positioning: Keep your LED grow lights at an ideal distance from your plant canopy to provide enough light intensity without causing photoinhibition or heat stress.
  • Daylight Simulation: Set up timers to mimic a 12-16 hour light cycles to deliver on appropriate DLI targets for your plants.

Humidity and Temperature

  • Increase Humidity: Keep relative humidity (RH) at 50% or higher by using a humidifier with built in hygrometer. Optimal RH is between 65%-75%, but this can cause mould issues indoors without adequate air flow so be aware if you're over 65% consistently.
  • Create a Micro-Climate: Group plants together to enhance local humidity levels. Skip the misting and pebble trays, these don't do anything for increasing the overall humidity and can cause additional issues for your plants.
  • Stable Temperatures: Maintain between 18°C and 24°C (65°F to 75°F), avoiding cold drafts and sudden temperature swings.

Soil and Watering

  • Well-Draining Soil: Use soilless grow mixes that retain adequate moisture without becoming soggy.
  • Watering Routine: Keep the soil evenly moist, without overwatering. Damp should be as low a moisture state as you want to get to so you ensure the permanent wilt point is never reached.
  • Fertilizing: Fertilize regularly to keep nutrient levels up.

Common Indoor Light Challenges

Indoor conditions can vary significantly from the stable and nurturing environment of a rainforest. While rainforest plants are adapted to specific light, humidity, and temperature conditions, the average indoor setting often falls short. Recognize when your plant needs help adapting to these different conditions:

  • Stretching: Long, weak stems mean it’s reaching for more light (etiolation).
  • Pale Leaves: Light-starved plants produce less chlorophyll. The reverse can also be true where plants increase chlorophyll to capture more of the available light.
  • Slow Growth: Growth is affected when there isn’t enough light.
  • Small Leaves: Reduced nutrient availability, insufficient light, low transpiration.
  • Dropping foliage: Insufficient light to support existing foliage

Solutions

  • Relocate: Move plants closer to windows or brighter spots.
  • Boost Lighting: Increase grow light intensity or duration.
  • Reflect Light: Place mirrors nearby or paint walls light colors to maximize available light.

Understanding Light Quality

Light quality is just as important as light quantity. Plants need specific wavelengths within the Photosynthetically Active Radiation (PAR) range, which spans from 400 to 700 nm, for effective growth. Each wavelength plays a different role in plant development, contributing to various aspects of photosynthesis and overall health:

  • Blue Light (400-500 nm): Promotes leaf growth and vegetative health.
  • Red Light (600-700 nm): Encourages flowering and fruiting.
  • Green Light (500-570 nm): Though less efficiently absorbed by chlorophyll, green light penetrates deeper into the leaf and canopy, aiding in overall plant growth and contributing to leaf coloration.

LED Lights: Full-spectrum LEDs mimic sunlight by providing a balanced range of wavelengths, including blue, red, and even green light, which are crucial for different stages of plant growth. These lights also allow for precise control over light intensity and quality, ensuring balanced growth by replicating natural sunlight conditions as closely as possible. Additionally, LEDs are energy-efficient, produce minimal heat on the illumination side of the fixture, and can be adjusted or dimmed to meet the specific needs of different plant species, making them an ideal choice for indoor gardening.

Bringing the Understory Aesthetic to Life

Cultivating rainforest plants is not just about creating ideal growth conditions—it’s also about crafting a lush, calming atmosphere that evokes the tranquility of the rainforest. The rich green foliage, the interplay of light and shadow, and the gentle humidity all work together to create an environment that feels like a peaceful escape from the outside world. By thoughtfully arranging plants, incorporating natural elements, and paying attention to the ambient conditions, you can transform your indoor space into a serene haven that nourishes both plants and people.

Design Tips

  • Layer Plants: Position plants at different heights, just like in the rainforest.
  • Mix Textures: Combine plants with varied leaf shapes and sizes for visual interest.
  • Natural Accents: Incorporate wood and stone to add a natural feel to your space.

More Than Just Looks

  • Air Quality: Many of these plants are reported to be able to help filter toxins out of indoor air, but don't believe all that you might hear.
  • Reduce Stress: Being surrounded by greenery can lower stress and improve your mood.
  • Learn More: Understanding the natural origins of your plants makes caring for them even more rewarding.

The Forest Floor (Conclusion)

By studying how tropical plants grow in their native rainforests, you can replicate those conditions to create the best possible environment for them at home. Embracing rainforest principles means ensuring adequate humidity, consistent temperatures, and proper lighting for thriving plants. When you succeed, you're not just growing houseplants—you're cultivating a piece of the jungle right in your living room. This approach brings a sense of lush serenity, transforming your home into a green sanctuary that offers both beauty and tranquility.

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