it doesnt matter how often you water.. it only matters how well you water them ... mulch them well ... are they mulched? insert finger to second knuckle.. and water them when it is dry or hot down there ... slow trickle ... water has to get to the roots... for it to be any good for the plant... if your watering is not getting down there... they will die ... how long it takes to get the roots damp .. is a function of your soil.. which only you can define and work with .... ergo.. insert finger ... check every plant ... once dampened to the proper level .... do not water again until hot or dry at second knuckle ... well mulched damp soil is never hot.. if the second says hot... its close to drying out ... dont be afraid to take a hand shovel and dig a 6 or 8 inch hole.. to see just how much water is down at the root ball ... ken

I would check for bagworms first. If there are no cases , then look for other pests. Could one tree be planted too deeply or be located in a site that is too wet? Link has pest and disease problems at the bottom of the page. Here is a link that might be useful: pests and diseases

Glen, I'm curious about how these plants were 'packaged when you bought them. They were containerized plants, weren't they? If they were balled and burlapped plants, I'd be a little concerned that the abnormally early start to hot weather might have hurt B&B plants that were planted in April. Also, did you check the undersides of the leaves to see if any sort of insect is eating on the leaves? The only issues I've had with Indian Hawthorne has been: (1) entomosporium leaf spot, which does not look like the browning you're seeing on your plants, and (2) occasional freeze damage (from a much colder than usual cold spell) that does leave foliage that looks like your plants. However, I'm fairly sure you aren't seeing freeze damage since the last freeze for most of us was in March, and for many of us it was in very early March. The fact that the plants started losing their luster and started getting brown leaves about a month after being transplanted does mean it could be transplant shock, which can show up in some trees and shrubs up to a year after they were transplanted. Has the browning continued since you first noticed it....like, is it progressing into more parts of the plant, or has it stayed exactly the same since you first noticed it? Also, have you used a trowel to dig down about six inches to check the soil moisture down deep? You said that the ones that had started to flower now have dried flower buds. Does that mean every flower bud dries up or just the ones on the same twigs as the browned leaves? Usually on this sort of thing, my gut instinct is right....but on your plants I have two different gut feelings--one is that they got too dry at some point and the damage appeared, but the stronger one is that it is a disease. However, I've never seen a disease do this to Indian Hawthornes. Hopefully, someone who has seen this on their plants will have an answer for you. If they were mine, I'd take some photos to the nursery where I purchased them and ask for their advice. Since they would know exactly what variety they sold you and what diseases or other issues might be common to it, they'd likely be your best source of advice in this case. If the browning doesn't progress and you start seeing new growth coming out that seems healthy, then I'd assume it was transplant shock. If you don't see new growth after a bit, then I'd consider that a worrisome sign in light of the browning foliage. Finally, with most plants, if you can irrigate with soaker hoses, drip irrigation lines or a hand-held hose that puts the water on the ground and into the soil instead of on the foliage, you can prevent a lot of the diseases that are encouraged by wet foliage. In the parts of Oklahoma that normally have wet, humid springs and summers, water on foliage just adds to the tendency for fungal and bacterial diseases to attack plants. I don't know if that is as much of an issue in western OK where the humidity often...

Debbie I don't think your tree peony can stand the hot sun for the next two months. If you cannot move it now drive four three inch wooden posts, ask for 'peelers' at Home Depot or Lowes and then staple 50% shade cloth over the plant. Tree peonies where you live can stand morning sun OK. Your herbaceous peonies like full sun about the same as most roses, with regular summer water. Peonies maintain their good looks after the bloom all the way through November for you and I. When the foliage(on herbaceous peonies)yellows about the first of December cut the stems down to about 4 inches. The stubs of stems left will protect the new buds forming for next years stems and flowers. These buds should be visible during the winter to get enough chilling for your peonies to bloom next year. Growing peonies successfully requires patience, especially in a marginal climate. Al