It's summertime! Our gardens are in full swing, tomatoes are beginning to ripen, berries are mostly done, and everything is lush and green. But beware, your plants can sunburn just like you. Sometimes we all need a little break from the heat, especially in the central and eastern portions of Contra Costa County where daytime temps regularly exceed 90 degrees.
Sunshine is necessary for plant growth, but too much can stress plants. Shade cloth (also called shade fabric) can block excessive sunshine and heat and will:
• Lower temperatures
• Reduce heat stress
• Prevent sunburn
• Reduce evaporation from the soil and the plant
• Reduce water needs
• Extend the growing season
• Expand the type of plants that can be grown
Selecting shade cloth
Shade cloth can block between 20% and 90% of the sun's rays reaching your garden beds, also called the transmission rate. A 30% shade cloth will reduce the sunlight reaching plants by 30% and will let 70% of the sun's rays in. The transmission rates will be shown on the product at the store. Delicate seedlings and cooler season plants (lettuce and spinach) will benefit from more shade (50–60% shade cloth), while sun-loving plants like fruits, tomatoes and peppers would do better with less blockage (20–40% shade cloth). Shade cloth is sold two ways: from a roll with a predetermined width and a length that you choose, or in pre-cut triangle and rectangle shapes. Shade cloth also comes in a variety of colors—black, brown, green, shades of beige, white, and sometimes less-common colors.
Installing shade cloth
Shade cloth can be installed several ways, depending on your garden layout. It can be spread over PVC hoops, also called hoop houses, or other PVC structures and secured with zip ties, ropes/twine, bungee cords, etc.
A triangle or rectangular piece can be installed like a sail attached to building edges or poles over the garden bed in a tent-like structure.
A DIY Frame can be made from fencing, vegetable cages, etc. and shade cloth can be draped and secured over the frame.
Be sure to attach shade cloth securely so that it does not flap or slide out of place because that can damage plants.
The vast majority of commercially available shade cloth is made from petroleum products like polypropylene or polyethylene. You may find shade cloth made from natural fibers such as jute, bamboo, sea grass, etc. but this is less common.
Give yourself and your plants a break from the heat this summer and for many summers to come by investing in some shade. It can help you use less water, prevent sunburn and heat stress, and extend your growing season. Enjoy your summer!
For more information about shade cloth in the garden, see this link: https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=55005
Help Desk of the UC Master Gardeners of Contra Costa County (DLB)