Experts and BHG readers answer.
Perennials all wilted
Thanks for writing. Without being able to see your plants, I can't say for sure what the problem is. Hot winds can cause plant leaves to lose more moisture than the roots can absorb, even when the soil is moist. If this is the case, you should notice that your plants recover at night and wilt during the day.
If the plants were grown in a cool greenhouse or otherwise not adapted to your current weather conditions, they may be stressed as they adapt to their new planting area.
If the plants get too much moisture, there's also a possibility they could be rotting in the ground as the roots drown.
If anyone in your neighborhood has sprayed any herbicides in the past week, there may be some that drifted onto your plants.
---Justin, Senior Garden Editor, BHG.com