Cover with Nursery Shade Cloth that provides 30%-40% shade. This cannot be purchased at the hardware store. Shade cloth that is available at the hardware store is only 75% shade, which is too dark for growing plants. I purchase my shade cloth online at: www.shadeclothstore.com
. They have very good prices and will build your shade cloth exactly to your specifications. I always purchase mine knitted, hemmed, and with grommets. The hem helps the shade cloth keep longer and the grommets make it easy to tie down the material.