I seem to be killing my lettuce seedlings!
Hi Guys, I'm looking for some advice. I'm clearly doing something wrong.
I'm trying to grow some lettuce, for latter transplantation into a hydroponic system inside. Mostly for fun but I do plant on eating my just reward in the form of salad later.
I planted 8 seeds in rockwool starter cubes. I soaked the cubes in water for a while, with a bit of vinegar to bring down the pH a bit. 3 days later, all 8 seeds sprout and show decent growth. They were under a 400w metal halide bulb. I watered them every day with a weak nutrient solution and left them under a plastic dome for a few days, the removed the dome. They stayed pretty moist the whole time. A week later they are dead and dying. Some fell over. The leaves started to yellow. Secondary leaves never appeared. I pulled one sprout that was pretty much toast, and the root was pretty well developed, but about the last cm or so was going black.
What am I doing wrong here?