Black vs. White Shade Cloth for a Greenhouse

We're often asked about the best shade cloth for a greenhouse. What color? What percent? What about the climate? With many options available, it can be confusing to decide where to start.

Shade cloth is a versatile tool that protects plants from UV rays, keeps greenhouses cool, prevents sun damage, improves plant ventilation, and helps soil retain moisture. But choosing the right kind matters!

Black Shade Cloth

Black shade cloth absorbs the sun’s energy, keeping your greenhouse warmer while preventing photo-oxidization (sunscald) and soil from drying out. Northern growers use it to increase greenhouse temperatures in the spring and fall, creating a warm environment for warm-season crops like tomatoes.

Research by Utah State University Extension shows tomatoes covered with shade cloth have 40% more leaf area and 50% more marketable yields than unshaded plants.

Black shade cloth retains heat during the day but allows it to seep out overnight, providing a consistent growing environment by lessening temperature shifts between day and night.

Light Filtration

Dr. Martin P.N. Gent of the University of Connecticut studies the use of various shade cloths in greenhouses and their effects on tomato quality. Black shade cloth helps reduce tomato blossom end rot (BET) when used with greenhouse plastic, preventing prolonged sun exposure damage and increasing marketable fruits.

Versatility

Shade cloth can be installed horizontally with low tunnels, hoops, or posts to create a canopy, or vertically between rows of north-south-oriented crops for sun protection. This makes walking through rows easier, and the posts can double as plant supports.

Examples of usage across zones:

• After transplanting crops like kale and beets in the summer, cover them for five to seven days with 30% shade cloth to help them adjust without harsh sun exposure. In zone 5b, the black cloth works well due to mild temperatures.
• Cover heat-loving crops like peppers in warm regions with white shade cloth to reduce UV rays while maintaining light quality.

White Shade Cloth

White shade cloth allows maximum light transmission without affecting light spectrum quality. It speeds up the growth of fruiting and flowering plants, is excellent for southern growers in peak summer heat, and maintains a healthy microclimate for heat-sensitive plants across growing zones.

Light Diffusion

White shade cloth scatters sunlight, protecting plants from sunscald, scorching, and hotspots while providing enough sun for photosynthesis. It encourages healthy root development, decreases stress, and increases yields.

Temperature Regulation

White shade cloth decreases greenhouse temperatures during peak summer, potentially reducing the need for fans and irrigation. Its reflective properties create a cooler microclimate, promoting consistent plant growth temperatures.

Energy Efficiency

Using a temperature tracking device can show decreased energy usage when using white shade cloth, as it can reduce reliance on other cooling mechanisms.

Farmer tip: Begin hardening off plants on a cloudy or partly cloudy day. Use shade cloth to reduce plant stress when moving to a new environment, starting with 50% and working down to 30% before removing it entirely.

Comparison of Black vs. White Shade Cloth

Light Transmission vs. Heat Retention

Both colors decrease the amount of sunlight, varying by density percentage. White shade cloth reflects rays and heat, while black absorbs and retains some heat, with white diffusing light more evenly.

Climate Suitability

Southern growers prefer white shade cloth for efficient light utilization and cooling effects, while northern growers benefit from black cloth's ability to extend the season, keep crops warm, and prevent sunscald.

Plant Type Compatibility

Cold-hardy plants like kale, spinach, and arugula benefit from the cool microclimate of white shade cloth, while warm-season crops like tomatoes, peppers, and cucumbers thrive with the warmth from black shade cloth.

Energy Efficiency and Cost Considerations

Northern growers can significantly reduce energy costs by using black shade cloth, which provides warmth on sunny but cold days, reducing reliance on heaters. White shade cloth helps maintain acceptable temperatures in the south with consistent deep watering, preventing overheating.

Shade Cloth Percentages

The percentages of shade cloth refer to the density and the amount of sunlight blocked. For example, 30% shade allows 70% sunlight, blocking 30% of light and UV rays. Choose the percentage based on your region and crops.

Growers north of the 40th parallel should select 30% shade cloth, while those south should choose 50%.

Bootstrap Farmer's Shade Cloth Options

Bootstrap Farmer’s UV-treated, knitted, polyethylene shade cloth is available in white or black, both in 30% or 50% shade. It has an 8-year warranty and a 16-year life expectancy, is mold and mildew-resistant, and the edges won't fray when cut.

Install shade cloth using a lock channel and spring wire or clips every 24 to 36 inches. Clips are made of 100% recycled materials and are highly durable.

Aluminum Netting: The New Shade Cloth Alternative

Aluminum netting offers significant advantages in terms of light diffusion, temperature regulation, and plant health, making it a valuable alternative to traditional shade cloth for certain growing conditions. One of the main benefits of aluminum shade cloth is improved light diffusion over traditional black or white. 50% aluminum shade has a light diffusion rate of 65%.

Aluminum netting is a high-density reflective polyethylene insulating product. Northern growers may consider it for its insulating properties, shading plants from the sun and reflecting UV rays, providing nighttime insulation up to 8℉.

However, its lifespan is around three to five years inside a greenhouse and only two to three years outdoors. It is also up to four times the investment. Despite the cost, it can be worth it for delicate ornamentals or cut flowers in zones six and below due to its insulating properties. 

Practical Examples: Implementation Strategies for Various Crops

• Use white shade cloth to prevent arugula, spinach, and kale from bolting and grow beautiful lettuce and cool-weather greens all season long. 
• Use 30% black shade cloth to protect young tomato transplants in cooler growing regions, allowing them to acclimate to their outside home while receiving 70% of the sun’s rays and providing warmth when spring nights are chilly.

Black vs. White Shade Cloth FAQs

What color shade cloth is best for reducing heat buildup?

Black shade cloth traps heat, so white is best for reducing heat buildup.

Does shade cloth percentage affect the amount of light transmission?

Yes, the percentage of a shade cloth refers to the amount of light transmission it blocks. A 30% shade cloth blocks 30% of light, allowing about 70% to penetrate.

Can shade cloth be used to reduce energy costs?

Adjusting the color and density of shade cloth throughout the season can decrease the need for heating or cooling, thus lowering energy costs.

How does shade cloth color impact plant growth and development?

Plants receive a full light spectrum under white cloth, promoting quicker growth. Research at Oklahoma State University shows that red, blue, and green shade cloths can be used for different purposes, affecting greenhouse growing in various ways.

Is it possible to combine different shade cloth colors in one greenhouse?

Yes, you can combine different shade cloth colors. For example, a greenhouse fully covered in white shade cloth to avoid internal heat build-up, with black cloth added to individual beds for additional shade for cold-sensitive crops in the spring and fall.

Is black or white shade cloth more effective for greenhouse use?

The effectiveness depends on the crops, time of year, and region. Both can be effective and used interchangeably as factors change. Check out our video comparing the shade cloths on a greenhouse.

Can I switch between different shade cloth colors during the growing season?

Yes. Select black shade cloth when you need warmth and sun protection; choose white to cool the plant’s environment and speed growth.

Are there specific shade cloth colors best for all plants?

50% white woven shade cloth is likely acceptable for most plants across zones.

Is black or white shade cloth better?

Choosing the best shade cloth depends on various factors. Experiment with different colors and percentages, taking notes for future reference. The goal is to control how much sun reaches your plants and how much heat they retain, creating a healthy growing environment.

What color is best for shade cloth?

• White shade cloth is best for flower, fruit, and warm region growers because it creates a cooler temperature for the plants.
• Black shade cloth absorbs heat, creating a warm environment for heat-loving plants like tomatoes, peppers, cucumbers, and strawberries. It is perfect for cool-region growers.

What is white shade cloth used for?

White shade cloth is perfect for warm region growers and those specializing in flower and fruiting plants.

Is black shade cloth hotter?

Black shade cloth absorbs and holds heat, creating a warm environment. The percentage of the shade cloth determines how hot it gets underneath.

Written by Jenna Rich of Partners’ Gardens