If you are looking at some extreme weather, keep your plants in the pots they are currently in and locate to a sheltered location outside. In your case, probably not in the sun. Probably a shady location. When the heat passes and your plants have become acclimated to your conditions, plant them.

When plants looks wilty because of lack of water, it's past time to water them. Some plants look wilty when it is really hot, but they recover when the heat passes. You may wish to find out from other gardeners in your location how much they water xeric plants. I live in NY State and my conditions are VASTLY different from yours so I can't suggest anything from my experience.

FataMorgana

To tell if a plant is wilting from lack of water IÂve been told to look at it very early in the morning, 5 or 6 a.m. or whatever is convenient for you. At that hour, at least in my climate, itÂs not wilting from heat. If itÂs wilting the leaves are going to feel soft & limp. You can help the plant by watering just before it goes limp. I feel the soil but I mainly feel the leaves. If the leaves have water in them they will feel stiff & "crispy" or "springy" at 6 a.m. Â the plant does not need to be watered.

However, if the soil is dry or sort of dry & the leaves are starting to go limp, I make a mental note at 6 a.m. that I need to water it. If itÂs a plant that gets morning sun, I donÂt actually water it until the sunÂs off it in late afternoon. If itÂs a plant thatÂs going to be in the shade all morning, I go ahead & water it at 6 a.m. because the water will dry by the time the sun hits it & the watering wonÂt burn the plant.

Have you tried the GW Texas forum for advice on when to put in the ground? I've just gotten some plants on sale that I'm putting in good-sized pots until Sept. or Oct. FataMorgana says, "When the heat passes ...." Except she's probably thinking of days or weeks & I'm thinking of months! Good luck!

You shouldn't use your garden soil for container growing. It will turn into something you and your plants won't be happy with in a very short time. Use a peat/bark/perlite combo and forget the chards in the bottom. Things like that don't improve drainage, they just take up valuable space. Use one chard, if you need to, to cover the hole in the bottom. I use plastic needle point grid for that job.

If you decide to purchase some ready made potting medium, try to find something without added moisture crystals, fertilizers, etc. Add a healthy amount of the perlite to it. Then you'll have something with good drainage!

I'd encourage you to judge watering needs by the SOIL, not whether or not the plant is wilting. How often depends upon how much sunlight, if the container is in a hot location (as in reflected heat or light), etc. You'll soon be able to judge.

We're having similar temperatures as you, right now. Horrible. We are watering most plants on a daily basis, though some get it more than that. You need to be generous with the watering. In a good, fast-draining potting mix, all of the excess will empty out rapidly. Then you can judge how long it takes for the soil volume to become somewhat dry. Never totally dry, just not cold and moist feeling. You'll need to use your fingers to judge the soil a few inches deep. Never judge by what the surface looks like.

Watering at mid-day won't burn your plants, but it's not the most efficient time. Early morning is probably best in terms of the plant's well-being.

Keeping the plants in their existing pots wasn't an option (one looked very dehydrated at about noon even though it was well watered the evening before). So yesterday I potted them up in cheap potting soil (it was what was in the shed) mixed with perilite and a bit of compost. I planted 3 plants in a 12" pot I found and 1 in an 8" pot I had. All have lots of holes in the bottom.

I used to have a soil moisture guage and was surprised how unreliable my finger tests were...I guess often the top couple of inches dries out but pots are still moist below. I'm getting another guage. My dilemma is knowing how long to let the soil dry out between waterings? Having been just transplanted these plants are going to be more vulnerable than established plants...I guess let the guage get to dry between waterings?

Well...I went on vacation and I believe all the herbs died in my absence. Temps were over 100 every day. I don't know if they died from stress, drying out or overwatering (one pot was totally dry the other very wet...my homesitter is obviously not a gardener)

I'm just wondering since these are perennials is there any hope their roots might live? Should I cut the brown stalks off and hope for signs of life?

I wouldn't cut anything yet but definitely try some TLC. You've got nothing to loose but some effort on your part.

I hope some come back for you!

FataMorgana

I've had mint totally dry up and crumble.. Kept watering it and it came back. It's always worth a shot . :)

JoJo

One precaution you have to take with potted plants in hot weather is not to let the pots themselves get hot. Wrapping the pots in bubble wrap will help keep them from overheating. The tops of plants can stand a lot more heat than the roots. All of the plants you mentioned will do better in the ground than in pots. Although they will tolerate drought, they will do better with some watering. Sage grows faster with regular watering but the flavor is more intense if kept on the dry side. Mexican oregano needs regular pruning or it will get very leggy with a lot of bare stems.

Thanks for the info hoodat - in hindsight I probably should have kept these herbs inside while I was gone -though they wouldn't have got as much sun their environment would have been much more stable for transplants. I'm going to getting some more in September and I'll bypass the pots and go straight to ground. I seem to have absolutely no luck getting perennial herbs to grow in pots -the annuals seem to do much better in the pots.