How Far From Grow Lights to Place Seedlings
December 23, 2018
A smaller two- to four-lamp fluorescent fixture can sit just a few inches above young seedlings. As plants grow larger, move the fixture a foot or so higher. Large fluorescent fixtures may need to be 2 to 3 feet above plants to avoid causing heat stress.
I use a large adjustable shelf with 4-lamp T5 fixtures to start seeds, grow microgreens, transition transplants. You might find large fixtures like these can get pretty warm so you may not need a seedling heat mat, or you can remove one or two bulbs to reduce light and heat load if it seems your young seedlings need a bit less of either.