[Danaus29]

Too cold, too much fertilizer, not enough air circulation.

Direct a fan at the plants to blow the heat away from them. The roots are staying too wet while the leaves are drying out. I just cooked my crossandra by not giving it enough air circulation. 50°f is a bit too cool for tomatoes. Can you bring up the temp just a couple degrees? Are you using the fertilizer at full strength? I would use only 1/2 to 1/4 strength fertilizer if using it every couple weeks. Set up a humidity tray near the plants but don't let the roots sit in water.

The white spots look like the beginning of some sort of mildew or mold. The edges of the leaves are brown because they are too dry.

 

[Danaus29]

Ah, so the temps are low only overnight.

Have you tried putting some sort of mulch on top of the soil? A mulch will keep the soil from drying out so fast.

You still should set a fan to blow the heat away from the plants and set up a separate source of humidity. A bowl or pan of water would be good for that.

 

[Danaus29]

On sunny days, I use a floor fan to blow hot air from that room into the rest of the house. I usually keep the sprinkler can full and setting on the table next to the tomatoes, plus I keep about an inch of water in the containers the grow bags sit in.

I tried watering less frequently, but the leaves stated wilting.

Is that fan blowing across the plants?

 

[Danaus29]

Can you set up something to shade the grow bags? I am assuming they are black. Black grow bags will get too warm with the sun shining on them.

The plants should have more air circulation during the heat of the day.

 

[Danaus29]

According to several articles your nightime temps need to be warmer. Some say 55° this one says 60°f.

Gardening with Allen: Help tomato plants set fruit

My tomato plants have produced dozens of flowers, but very few fruits have set. I have even shaken the flowers to make sure they were pollinated. Can you tell me what is wrong?

www.columbian.com

I have tried tomatoes but my basement is just too cold. I have kept ornamental peppers and got fruit from them. Peppers are a bit more forgiving, and a lot more expensive at the store. Besides, peppers take a lot less room.

 

[Danaus29]

Onions like the cooler weather too. If you like kale it does very well indoors.

Spring is on it's way. If you can keep your tomato plants alive for a few more weeks they can be set outside.

Next time you could try some of those container culture tomatoes. The plants don't get very big and they are hybrids that produce cherry or grape tomatoes. But even when grown indoors those tomatoes would taste better than any store bought tomatoes.