The care information provided in this section represents the kind of practical advice is available for all the plants in this web site if you subscribe to the monthly customized newsletter Yardener’s Advisor.
Hydrangeas like to be kept moist. Not only is it important to water newly planted shrubs regularly for a few weeks, but even established hydrangeas appreciate supplemental watering if rainfall is irregular. In the event of a mid-summer drought it is particularly important to water as soon as the soil dries out.
These shrubs will signal their thirst by drooping visibly the minute they feel dry. They wilt when the temperatures heat up. They lose moisture through transpiration faster than their roots can take it up. So it's possible to water them well one day and find the plants wilting in the noonday sun the next. However, if the plant remains wilted in the morning, it should be watered immediately.
For more information see file About Watering Equipment.
These hydrangeas are fairly heavy feeders. Sprinkle a handful of an all-purpose granular fertilizer (preferably with a slow release form of nitrogen) on the soil under each shrub in the early spring for the rain to soak in. Do not feed them in the summer, because the new growth that will result is vulnerable to early fall frosts. Spread the fertilizer on the soil out to 1 foot beyond the tips of the branches (the drip line).
For more information see file About Fertilizers.
Spread a layer of organic mulch 2 or 3 inches thick on the soil under each hydrangea. Either alone or over landscape fabric laid on the soil first, a mulch of chopped leaves, wood chips, pine needles, peat moss or the like, will deter serious weed problems and help maintain soil moisture. It will also protect shrub roots in the winter from the heaving of soil subjected to alternate freezing and thawing. Mulch around the stems of panicle hydrangeas grown as trees reduces their vulnerability to injury from mechanical yard care equipment.
For more information see files on Using Mulch and Winter Protection For Plants.
To prevent panicle hydrangeas from rapidly becoming woody and brittle, prune them back hard each spring. Try to cut off the previous year's wood back to only 2 buds. Cut back some branches completely to encourage larger flowers on the remaining ones.
For more information see file on Pruning Shrubs and Hedges and Choosing Pruning Tools.