my cuphea is sick

This is cuphea, either ignea or melvillia. Cigar plant can refer to either, I believe. It is in a container in the blazing Texas sun from mid-morning until the last rays of the sun. I water it only when it becomes dry, but that is often. It did well for several weeks but the leaves are turning dark, almost black. It has not been a profuse bloomer, but it's still blooming. I suspect it is a cultural or environmental problem, but I understood that it was a good choice for hot sunny locations. Any ideas on why this is happening?

TKS

DP

The reddish coloration to the leaves could signify a lack of phosporus. But another possibility is a pot sitting in the blazing sun...the roots get much hotter than when it is in the ground. How big is the pot? Is there enough soil to help insulate the roots from the heat? My cuphea is in full sun, too, but in the ground, and doing fine...

I agree - the problem is cultural.

It's even worse than I described. I am in a patio house and because of its design, all my plants are in containers SITTING ON A CONCRETE SLAB facing west. I have tried many plants here. Pentas are the most successful, but I have to watch their watering needs like a hawk. Lowly periwinkles do fine; some coleus truly are sun coleus, but many are NOT. Esperanzas are almost foolproof. Batatas ipomoea even show stress. Trailing lantanas do all right, and a couple of strap-leaf caladiums if up against a wall and partially shielded from the sun. I'm going to write this off as heat stress and move on to the next experiment. Thanks very much for your reply.

DP

It might help if you can group pots together, to shade one another. I would use large pots too. Using plants from the western states and Mexico might have its advantages, with less water, so they don't get root rot. Could you pot up some smaller trees to sit on the edge of the patio and provide a little shade? Just some thoughts.... You have a tough environment there.

Does your patio have a roof or even a pergola sort of thing over it or is it completely open to the sun? I had a west facing covered patio at my old house and it was a nice place to grow plants, but I think if it hadn't been for the patio roof everything would have fried. So as a long term solution you might consider something like that too. If you've got some DIY skills building a pergola type thing over the patio will probably be the cheapest option and will look a little nicer than my covered patio did (it had a kind of ugly metal roof). Or you could look into retractable awnings, depending on the size of the patio that might be an affordable option too. Plus if you do a cover of some sort, it'll make it more pleasant for you to spend time out there in the summers--I'm guessing you don't spend too much time out there now during the day!

Also make sure all your pots are the lightest color possible--if you keep things in those black pots they come in from the nursery that'll cook the roots very quickly, but a light colored container won't be as bad.