Answer: If the branch tips are wilting it could be lack of water or it could be heat stress, or it could be a combination. New plants have limited root systems and may wilt temporarily on hot afternoons, then recover when it cools off and look fine the next morning.
If the soil is damp like a wrung out sponge, not saturated/sopping wet and not dried out (use your finger to check it, check both the potting mix and the surrounding soil as they sometimes dry out at different rates) do not water it. Overwatering can cause root problems, so it is not good to over or under water.
Using several inches of organic mulch over the root area can help keep the roots cool and also keep the soil moister longer. Apply it in a flat layer over the root area but do not allow it to touch the trunk.
I am a bit concerned about the extra heat reflecting off the stone wall. This tree can reach 15 feet across (larger in time) so it should be quite a distance from teh wall to allow for that growth.
You are in a warmer summer heat zone than this plant typically tolerates. Going by zip code your summer heat zone is 8. This particular pine prefers cooler summers and so is rated for the next coolest zone and cooler. (It is native to a more northerly area so has great cold tolerance and limited summer heat tolerance.)
If it is next to a wall, it will make that site even hotter than normal. It sounds a bit odd, but if you could shade it with a sun umbrella during the hottest part of the day, that might help. (You would only do that this summer while it is becoming rooted.) Or, you might consider moving it to a cooler spot, say sun all morning but shaded in the afternoon.
Since this is a new tree, I would also suggest you consult with your retailer, especially if it is under warranty. Good luck with your pine, it is a gorgeous plant!
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