I'm by no means an expert with this veggie thing. This is my first year to do them. But I noticed that when I transplanted them from inside out it took them a day or so to get used to the new soil and regain their strength. That is just my expierence. I'm not sure how big your plants are or if they are well established, as mine were not, but have since jumped back and are growing well. I'm sorry if I was of no help, but I thought I'd share what I've expierence with you.

High soil temps can assuredly cause wilting, but so can over-fertilizing, over/under-watering, and some nutritional imbalances/deficiencies.

Going strictly by odds, if I had to pick the most likely source of your wilting issue, it would be over-watering.

Al

I try to only water when the top of the soil looks dry and the soil underneath isn't very moist. I havn't watered in about 4 days supposed to rain tomorrow. If I placed mulch in the containers would that help the wilting. The heat of the days gone and they don't look wilted anymore. They've been in their spot for 3 weeks now.

I can think of two ways mulch would be helpful. One is if the soil is drying so quickly the plants are suffering from drought stress and wilting before you have an opportunity to water, but from your description, that's not the case. The other is it might help ameliorate high soil temperatures by virtue of the shade it provides the soil surface. How significant an improvement this might be is kind of iffy and based on how much sun actually strikes the soil and/or how much shade the plant material is already providing for the soil. If you actually NEED the shading effect of mulch to help lower soil temperatures, you should probably be considering other methods more effective at reducing soil temps, like cache pots (pot-in-pot growing), shading the pots, or growing in only light colored containers or terra cotta.

I'm still not convinced it's due to soil temps. I think it's probably related to either an underdeveloped root system or a soil that is impeding root function/metabolism because it is holding too much water/too little air.

Al

Thank you very much for the input I appreciate it!

I am probably too simplistic a thinker. My thought on my plants wilting during the heat of the day, especially the first few really warm days of the season, is the roots are not able to replace the moisture lost through transpiration, as fast as it is lost. Many possible reasons have already been mentioned. Not enough roots, or too much foliage. Not enough water in the root zone. Too much water in the root zone, which often means not enough air and roots unable to take up water although they are drowning in it. Too much heat at the roots,especially black nursery pots that get too hot to handle,again making the roots ineffective. Sometimes it is simply the plants in question were never intended to be grown in the full sun and will wilt in it with no remedy, other than moving the plant. Once the gardener determines which of the possible causes is his problem the cure is simple. I TOLD you I was too simplistic a thinker. Al