Answer: Hollies are best planted in early spring so they have time to develop their root sytems before the heat of summer stresses them. So to some extent what you are seeing may be the result of transplant stress. The best you can do is keep them watered correctly.
Over watering and under watering can both cause drooping or wilting due to root damage. Your goal in watering is to keep the soil evenly moist like a wrung out sponge, not sopping wet and not dried out. To know if you need to water, dig into the soil with your finger. If it is still damp, do not water yet. When you do water, apply it to the soil surface and water thoroughly and slowly so it soaks down to the deeper roots. After watering, wait a few hours and then dig down to see how far the water soaked in; it can be surprising.
There is no set schedule for watering, it depends on your soil type and on the weather. Using an organic mulch several inches thick over the root area will help reduce watering needs as well as feed the soil gradually as it breaks down over time.
Another thing to check is that they are not planted too deeply. They should be no deeper than they grew in the container. Any encircling roots should have been cut at planting time to prevent them growing in a circle underground. Do not fertilize them now as that will add additional stress.
Since they are not looking good, you may want to consult with your retail store, especially if there is a warranty involved.
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