I don't have a lot of experience with hydrangeas either, but I wanted to say that my young Horwack/ pistachio also has not done well in full sun here (zone 6b-- when I say young, I mean it's less than a foot tall or wide). I moved it to a shady area on the side of the house where it probably only gets 3-4 hours of sun a day (afternoon sun; morning is better for hydrangeas but I didn't have a spot there), and it's doing a lot better, no longer wilting in the afternoon, growing new leaves, and the existing leaves are no longer burning. I don't think it's going to bloom this year, but I expected that with the size of the plant.

I don't think Horwack is as sun tolerant as some other varieties of macrophylla. I have heard that most hydrangeas do better with morning sun versus afternoon; could you plant them on the east side of your house?

Keep them very well watered. That's really important for the first year at least, and will help with the full sun to some extent. Don't get the leaves wet, especially if the sun is shining on the plants when you water-- that'll make them more susceptible to fungus when they are already stressed, and the sun will burn them worse with wet leaves.
You could rig up shade clothes to protect the plant from full sun, focusing on reducing the afternoon sun. That's probably the best thing you could do for them if you want to keep them in that location (but I understand the "best" option is not always possible).

Older hydrangeas with well established roots are supposed to be more full-sun tolerant, but young, small hydrangeas will need to be very well watered, and babied (possibly with shade cloth) for the first year and maybe another summer after that. Would you still transplant them into pots so you could keep them in a shadier location until they are more mature?

I don't have enough experience with pistachio to say whether they ultimately will be happy in full sun or not, hopefully someone with an established pistachio in sun will come in and let us know. I had planned pistachio for that shady location because I knew it wasn't as sun tolerant as the everlasting revolution hydrangeas that I purchased at the same time. Honestly, one of the revolutions (which gets full morning and afternoon sun; the other gets sun from 11 am and onward) is getting a bit scorched as well, so I've been trying to decide about rigging up some shade cloth, myself. For now, I'm just keeping it very well watered and checking it regularly (it's fairly minimal sunburn compared to many plants I've seen here; I think it'll be fine once it's better established).

I'm sure a picture of your plants and the sunburn will help anyone else who drops in to give you advice, if you have a picture. :)

Good luck!

Vinsone, do you mean South Dakota by SD? If so, follow the link below to find your hardiness zone. Looks like that would place you somewhere between 3b (-35) to 5b
(-15). Pistachio is only rated hardy to -20F. If you're in zone 5a (-20) or 5b, it may work for you if well-sited & heavily Winter protected. If not, you may have success growing Pistachio in pots overwintered in a garage or other shelter.

What size pots were your Pistachios in when you got them? Pot size often indicates the age of a plant, with smaller pots for younger plants. I'd be hesitant to plant anything less than a gallon directly in the garden myself. Many pot up smaller sizes into larger pots as they grow to give them the advantage of more controlled conditions till they're more mature, often growing them along in pots & planting out the following Spring after late frosts are past.

Depending on your zone, you may find your Pistachios able to adapt to 9-10 hours of sun as they get older, but that's a lot of sun. The tag that came with mine says morning sun, afternoon shade. In the meantime, if your zone allows for growing them in the open garden, shade them past noon while they're so young. Lawn chairs, cheap umbrellas stuck in the ground at an angle to deflect noonday sun, replaceable cardboard propped with stakes or any other juryrig that comes to mind & hand will do in a pinch. Agree with livrerosa's sound advice. If you have a "mist" setting on your watering handle, fine misting is helpful to hydrate the leaves when the rootmass isn't established or large enough to deliver moisture to them under stress. You can mist them in the morning before the sun hits and later under shade with positive benefits several times a day. Mulch helps protect the roots & lower the soil surface temp, but keep it from touching the stems.

Trialing two Pistachios in 3-gallon pots here in zone 7a central Virginia the past month, find them doing fine with 7 hours of full sun in an ESE exposure with daytime temps ranging from 70-98. They may take more hours of sun than that - haven't tried. Kept well-watered once a day, no scorch or wilt yet. Bought in bloom & bud, first flowers still fresh, original buds blooming & new buds coming along. With new additions of uncertain sun-shade preferences, like to keep them in pots for a season before planting early September or so, which this zone allows. That way they can be easily repositioned to change exposure if indicated. (The lazy gardener's way of finding their best spot.) These 3-gallons are ready to be moved to 5-gallon pots, and two 1-gallon mophead hydrangeas of other varieties bought late Spring have already been repotted to 3-gallons. You may find it easier to pot your Pistachios now, give them afternoon shade, and plant out again when they're more mature & able to handle your garden conditions.

Here is a link that might be useful: {{gwi:1008772}}

This post was edited by vasue on Thu, Jun 26, 14 at 11:37

HD has some larger hydrangeas in Vigiro pots that say Pistachio but no blooms so I wonder.....

Move them to a morning sun location.

Hokierusty, I'd be hesitant to buy any hydrangea not in bloom, too. If in bud & returnable, would take a chance. Local Lowe's still has a couple 3-gallon Pistachios squished in with loads of new various arrivals, and remarkably they still look good under their care after sitting on the sale table for 6 weeks. Any at your Lowes? Really liking Pistachio - the buds & blooms just keep coming from every node, coral pink main color still, though some of the lavendar pincushion centers have morphed to blue as the older blooms age.

Not here at Lowes but next time in Richmond will check there.

Thanks guys i have Jerry-rigged up some shade cloth so they get sun through till about 12:30 -1:00pm and they have started to sprout alot of new leaves and i also got a dripper hose for them which i turn on every two days for 30 minutes they seem to be happier. The nursery i got them from said that they would probably servive the freezing winters here. The pots they came in where those small little square ones maybe 2 inches wide, they only had one stalke grown when i got them and now 3 of them have 3 or 4 i also have put river rock as a top layer (we get extremely bad wind storms here and it is the only thing that will not blow away. Any more experiances or info you can give me about these plants is very much appreciated. Do you think they will bloom next year or is that asking a little to much of them?