Lack of water will do it. Root rot also will produce those symptoms. Windy days can also make those shrubs wilt.

To address the first problem, mulch with 3-4" of acidic mulch a little past the drip line. Water when the soil feels almost dry or dry. If the wilting episode looks extreme, water immediately but otherwise, wait until nightfall or better yet, next morning. Established plants will recover by then.

If the plant has not recovered by next morning, water. Wilting is a natural response of all large leaf shrubs when they cannot absorb water through the roots as fast as they loose it through the leaves.

Root rot is caused by fungal problems and too much watering. Its symptoms are similar to those of lack of moisture. To keep this problem away from your garden, locate the shrub in well draining soil with organic compost & water when the soil is almost dry so the roots are not kept in wet soils for long periods. Once this problem starts and the roots decay (turn brown-ish instead of white), it may be impossible to stop the damage. It is difficult to tell which plant can overcome this and which ones cannot. So provide constant soil moisture. Make sure the soil does not feel wet (except when it rains or you water) and mulch.

There is little one can do about windy days except use a wind break, move the plant elsewhere or add some extra water the night before a wind advisory has been issued on the news.

Does that help you Amy?
Luis

I'm guessing lack of water...Hard to tell for sure. For me sometimes leaf rollers will cause similar problems - can't see the leaves very well in the picture. For us it is a very dry spring here. We don't normally water this early but have had to a few times already.

Could it be herbicide damage? Anyone, neighbor on the other side of the fence, maybe, spraying weeds?