Agree that you wouldn't see yellowing leaves from UNDER-watering. It is an issue that develops from over-watering, either too much at one time in poorly draining soil or watering way too often.

Watering everyday is never needed for in ground plants except maybe in the dry desert southwest in the 100+ degree days of summer. And air temps at any one time isn't really relevant. The amount of moisture in the soil is what matters so you get your hands dirty to find out. You stick your hand down into the soil, not the surface, and feel it before you water.

Dave

The main symptom of underwatering will be overall droopiness. Not yellow leaves. But you can let the surface of the soil dry out. That's not where the roots are. Yellow lower leaves are often where the plant can't get enough oxygen or other nutrients, often because it's drowning. But they can also be from soil deficiencies.

Agree with above ( Dave and Dan) .

Under watering can cause darker foliage an in extreme cases wilting of the lower leaves. In high temperature most leaves wilt.

Sey

@daninthedirt

i transplanted my tomatoes after a few days worth of showers. I was warned that wet soil might offer less oxygen. However I was also warned to plant on an overcast day and my forecast predicted a week worth of full sun and 80+ following that overcast day I decided to transplant.

I did my best to dig out a much bigger hole than was needed and tried to gently add soil and the roots to that hole so there wouldn't be any mud or some other problem restricting oxygen.

You weren't able to see the conditions but do you think that could be the problem, and if so, should I dig out my plants and then try it again (they have only been in the ground a week)?

or do I just hold off on watering, other than what nature brings, until the soil gets dry under the surface?

Thank you to all who helped.

The tomatoes will recover (they're pretty resilient). Just pull off the damaged leaves, and let the soil drain. In order to decide when to water you need to stick your finger an inch or two into the soil and see if it is moist. If not, then water. In the highest temps, you shouldn't need to do that more than once every few days unless the soil is extremely sandy.

After some experience you dont even need to mess with the soil. Just let the plants tell you when it is time. And you will know when to water just based upon your local rainfall.

As Daniel say, don't dig them up.

That's an important point. Your plants will tell you when they're thirsty. Tomatoes will start to wilt or droop subtly. When you see that, get out the hose asap. We're talking *subtly*. Don't wait until the plant has keeled over. With experience, you'll notice.

2 years ago I planted about 20 tomatoes on one of my lots.

ONE of those tomatoes, whenever the soil was dry, it started wilting, telling me that it's time for the drip irrigation to do its job. Only THAT tomato started wilting, all the others were ok.

That plant never failed, and all the other tomatoes very happy.

No under-watering, no over-watering. Just perfect time.

My point - as some already said above - is that the plants will tell you when they are thirsty.

They will simply start wilting.

Before watering, I suggest you to check the weather forecast.

You don't want to water today, and the next day it... rains.

A few years ago, I over-watered some tomatoes, and they were mushy, watery, not yummy. I reduced A LOT the watering, and the tomatoes tasted yummy.

Some here in this forum, do not water AT ALL during the month of August.

For some areas in the US, this could be somehow extreme, but for many other areas - imho - I think this could be a good idea.

The plants will tell you anyway if they are thirsty or not.

Yes, but not all wilting in the garden is due to lack of moisture in the soil. After few days of cooler/cloud weather when suddenly sun comes out and the temperatures go up, you might see a lot of wilting. But when the sun goes down they all will perk up. That is when finger checking soil can come handy.

Sey

6/27/17 : Case in Point.

Today after 2 weeks of cool weather combined with some rain and overcat skies, the sun came out and the temperature reached 87F. Guess what ? all my plants were wilting. I checked the soil moisture . It was fine. So I ignored them. Let them tough it out. hehe