Q. My tomatoes, peppers, cucumbers, and cabbage are dying only hours after taking them outside! What have I done wrong? The room they were in has a West-facing window, so they received 2-3 hours of sun on sunny days. I put fertilizer in the potting soil, but did not feed them after that.
A. It is so important that plants receive full sun for 8+ hours per day from the moment they poke their heads above ground. Lacking actual sunlight, they have to have a warm and cool fluorescent tube placed about 1″ from the surface of the plants for 16 + hours per day.
Failure to give your plants adequate light in the house-made them very susceptible to burning up in the heat and light of the full sun.
They were also very weak from lack of food, which also made them unable to handle the stress of a changed environment. ALWAYS water your new seedlings with the Constant Feed solution of 1 ounce Mittleider Magic Weekly Feed in 3 gallons of water, and they will be healthy and strong, and much more able to handle the shock of hardening off and transplanting. And of course, they will be much bigger also.
How about pruning. You also must keep them pruned so the leaves do not overlap. This creates small shocks, and gets the plant to grow a stronger, thicker stem – also preparing it for the harsh reality of the outdoors.
I suggest a good nursery, to get you some healthy plants, so you don’t lose the season. The ones you describe will not recover, and will never produce a good crop.