Boris - thanks for replying. As a result of my inexperience, I chose an indeterminate variety (Damsel Hybrid, from Burpee) - I now know that plants that grow as large as these can are not container-friendly. Next year I'll go with a compact determinate of some sort, or at the very least move up to 20-gallon grow bags similar to those you're using. I didn't get them outside until May 26th as the weather didn't really feel favorable until then and I didn't want to stress them with night time temperatures in the 40's still on occasion. In any case, these plants are about 4.5 feet tall at the moment (one is almost 5 feet tall) and all have set fruit. I've got at least 4 growing tomatoes on each plant at the moment, and more appear every day. I am glad to report however that they have recovered considerably since earlier tonight and are pretty much back to looking like their normal hardy selves. There are some wilted leaves but overall they look much better. Maybe I am babying them too much but I felt like they needed a break this afternoon and put up a large umbrella to partially shade them from right around when I posted the original message until dark. They seem to have responded well to that. I'll probably do that again tomorrow as it's going to be close to 100 degrees again. Your description of how much you watered is very helpful and helps to verify that I'm not over-watering. The reason I chose the grow bags in the first place was to avoid over-watering. Thanks for your help and good luck with your tomatoes this year!

If your mix is draining ok, no need to worry about overwatering. Water whenever they need it. The umbrella should help during the heat wave. I use larger pots and probably could water twice a day during hot weather. Large tomato plants drink mucho water.

The plants have certainly maxed out the 5 gallon containers - so the roots are right up to the edge of the fabric. That, plus the fact that they are not underground where the temperature is cooler and more consistent, means they are taking the full brunt of the heat. This will make them very vulnerable to temperature, since they have no insulation or buffer.

It sounds like watering 2x a day during the heat might be a good amount. In addition, soak the outside of the containers as well to dissipate some heat.

If possible, you might consider transplanting them into 15 or 20 gallon fabric pots. They won't grow as big as if they has been there from the beginning, but at least the roots will have some buffer from the air temps.

As for the tomatoes themselves, as long as the plant is adequately hydrated and fed, the plants will grow to whatever size the container can sustain and then produce fruit.

I own a 5gal fabric pot and have been using it in this past weather. I ended up giving it, and my other 5gal pots in pails, about 2gal/day of water.

Indeterminate variety.

And I can also assure you, based on personal experience, that 5gal sized containers with good potting mix is "fine" for indeterminate varieties. As long as you like watering.

I have 5 indeterminate tomatoes in 7 gallon fabric pots. They each have a 2 gph dripper that runs 20 minutes in the morning and at night. They're growing great even though we've been getting some temps in the 90s+ pretty often this year (I'm in Northern California). Previous years I tried to just hand water but I couldn't keep up with it and they got pretty stressed. I also give them some ferts (including calcium and magnesium) on the weekend.

Cherokee Purple last weekend

Lillian's Yellow last weekend

Thanks for all the input everyone. I've switched to watering twice per day since I now know that I am certainly not over-watering. The plants are doing much better overall and even seem to be thriving to a degree in this heat (it is 99 degrees here at the moment and will likely top 100 again today by the end of the day). The tomatoes growing on them are progressing nicely. Again, I appreciate the help.

If you don't like watering, because let's face it most people don't, you can put some plastic bags on top of the soil (white grocery store bags are great!) and the evaporation will go down to almost nothing. Will save tons of water, you might go from 2x daily to once every two days in the crazy-high heat. At least I was able to for some plants.

its been 95-105 for the past month. my tomatoes in grow bags get water once a day and sometimes every other day and they are doing great. 100 and above daily and below 100 every other day. I'm using a 3-1-1 in my root pruning fabric grow bags.

Fabric pots lose water really fast. Not a great choice without automatic watering. Just keep watering them and don't forget to add fertilizer which you are losing.

Hi I am growing tomatoes ( indeterminate ) in 20 gallon grow bags as well in zone 7b. I used straw mulch to help hold the moisture in the container. It’s hard for me to tell if the potting mix is wet throughout the container as the top always seems to stay moist. Should I always water daily? Should I water until I see the water coming out from the bottom of the bags? Also, when should fertilizer be applied? ( after fruit set ) thank you!