Grow lights drying top 1' of soil. Not absorbing water.
Started growing several varieties of vegetables from seed indoors in 144 1" seed trays. Everything is going well. I transplanted to 3" pots. Growing under 12 4' t5HO lights. The lights are about 4" from the tops of plants.
Im down to watering (depending on variety) thoroughly every 5 days. However, the last time I watered, I noticed all the water just ran down the side of the pots and out the bottom. the top 1" of soil has become hardened and crusty and the soil around the edge of the pot has "shrunk" a fraction of an inch. I think the heat from the lights caused the top to get crusty. And the sides shrunk because of slight soil compaction. Thus,true soil isn't absorbing the water and the plant look a little droopy (like they normally would when lacking water)
One other interesting note, I am using clear plastic cups and can see the roots coming down the sides of the pots, I think more so than normal because that is where the water is.
Have other people had this problem? Suggestions?
Also, my first thought was mulching. Suggestions for mulches for indoor 3" pots under grow lights?