On hot or windy days my hydrangeas wilt completely, even if the ground under them is moist. What’s going on?
When plants wilt despite plenty of moisture in the soil, it’s not water they lack—it’s roots. Soil that is rich in organic matter, deep, loose, and porous, promotes extensive root systems that sustain plants through brutal heat and dry spells.
Unfortunately for your hydrangeas, the time to work on creating ideal soil is before you plant. It also helps to locate plants that are prone to wilting, like hydrangeas, where they will get sun in the morning and shade in the afternoon. Other chronic wilters, like impatiens, are more likely to stay hydrated in all-day shade.
Now that summer has set in, help your hydrangeas through the heat with a cooling layer of organic mulch on the soil. Mulch maintains soil moisture, reduces competition from weeds, and slowly adds organic matter to the soil. Your hydrangeas might also benefit from a cooling spray of water at midday, if you are so inclined. —Doug Hall