Q. I had three tomato plants, all started from seed. They were all very healthy and thriving beautifully. They were planted in a grow box filled with growing media. After about 5-6 weeks the leaves started curling up on all three plants and after about 2 weeks all plants died. When I first noticed the problem, I looked it up on the internet and it informed me it was a watering problem but not to worry. I didn't worry and they all died.
A. I don’t know if you saved the seed from other tomatoes or you bought the seed and where you bought it. I also am not sure if they were grown as transplants in the home and then moved directly into the garden.
Acclimating transplants (hardening off)
If these tomato plants were grown from seed inside the home and then moved into the garden, they need to be acclimated to the weather before planting. Inside a home or greenhouse there is protection from intense sunlight, higher humidity and very little wind.
Acclimate your seedlings to our weather by putting them outside in light shade or the east side of a building. After two or three weeks and you see some new growth, they are ready to go into the garden. Some old-time gardeners will put a wooden shingle on the south side of the plant to give them some protection for another couple weeks.
We used to use coffee cans too.
Acclamation helps plants adjust to our desert climate and weather conditions. They go through a lot of shock if planted directly into a garden or grow box from inside a home or greenhouse. Sometimes planting them directly from a protected environment into the garden will cause them to die.
The other possibility can be watering too often and poor drainage. If the soil stays too wet and the soil does not drain water easily, the roots can rot and the stem can develop collar rot. It looks like they aren't getting enough water so most people water more often. Big mistake. The soil needs more amendments and the transplants watered less often.