Written by Shawna Coronado
Summer heat can be devastating for your Square Foot Garden, so understanding how to use shade cloth can help your plants thrive during the extreme sun and humidity of these hotter months. Just like we humans, plants sometimes need to get out of the hot sun and under the shade to sip a cool drink and take a break from the sweltering heat.
What is a Shade Cloth and Can it Boost Production in the Garden?
A shade cloth can be DIY, such as an old white sheet, floating row cover, window screen or a piece of lattice. It can also be a roll of lightly woven material purchased to shade your SFG. Whatever kind you use, it will reduce how much heat can reach your plants via sunlight. Shade cloth is used for vegetables, annuals, perennials, shrubs and even fruit trees in order to reduce the heat zone and protect the plant from sunburn and scald.
It sounds crazy to think that shading your plants might increase production, but scientific evidence points to increased crop yields, improved photosynthesis and a longer growing season when covering plants properly. Typical photosynthesis occurs when leaves are between 50 to 68 degrees Fahrenheit, with more sunlight equaling better production – until it becomes too hot. Once the thermometer starts to rise over 80 degrees, then fruit production can stall in many vegetables and herbs. Therefore, shading plants during intense heat can boost plant yields.
Quick Tip
Use an umbrella and move it around to shade your SFG as needed throughout the day. We understand some folks may not want to build a shade cloth structure and this is a “quick” solution.
3 Reasons to Use Shade Cloth In your SFG:
- Solar Radiation Protection – Chief on this list is that it protects from sun radiation because too much sun can be a very bad thing. With excessive heat and sun exposure, some plants can suffer leaf curl, browning and scorching. Sometimes it is even beneficial to cover plants in extreme cold to protect from sun scald. No matter the season, we must be cautious of the sun’s damaging rays on our gardens.
- Pest Protection – Shade cloth protects the garden from severe heat and sun exposure, but depending on the type of cover it can also defend your garden against insect and bird attack.
- Soil Moisture – Often when you use a shade cloth, it helps your plants retain more water. With less sun beating down on your Mel’s Mix™, the less likely it will dry out, helping you conserve water and moisture. Keeping roots cool in general is a smart plan in order to stave off drought and to keep the plant in the cooler photosynthesis production zone.
Which Types of Shade Cloths Work Best for SFGs?
Loose woven shade cloth, ideal for medium shade over SFG or to use in small squares, as shown below.
Shade cloth comes in various colors, different types of material and density levels – how much sunlight the cloth physically blocks. More important than the fabric type is the density level. When you purchase shade cloth, 10% density provides light cover as it blocks only 10% of sunlight. On the other hand, an 80% density cover will block 80% of the sunlight.
Why different densities? Vegetables or herbs that need tons of sun will not grow well under a shade cloth of 90% density – it’s way too dark for the plant to flourish. Conversely a plant that is a shade lover like cabbage or chives will fry in full sun in the heat, so it would not survive with only a 10% shade cloth. Select shade cloth covers that help tone down the intense sun without cutting the plant off from its ability to photosynthesize. Typically, this means a shade cloth between 30% to 60% will work for most SFG situations.
Vent and Tent for Optimal Results
Create tents over specific squares with plants that need more shade.
Finding shade cloth that allows for good ventilation means that plants below it will also stay cooler. Knitted shade cloth, for example, lets more air pass through. Also important: do not lay shade cloth directly on your plants as the weight can break branches and damage the plants. Find supports that lift the shade cloth above the garden to deliver damage-free shade and needed air circulation.
Overall, shade cloth is a critical addition to your Square Foot Garden in these peak growing months when the sun is at its hottest. It will extend your plants’ longevity, producing a more bountiful harvest.
Learn more about the Square Foot Gardening Method by taking the introductory course.
