Healthy, happy plants produce large round balls of flowers that persist throughout the summer. Hydrangeas require steady care in the home landscape to promote full flowering. Despite the best care, these fickle plants often take a year off before blooming even heavier the following year.
Hydrangea plants prefer morning sun. Choose a location that features protection from the heat of afternoon sun. Plants will wilt in full sun locations and require considerable water to maintain foliage.
This plant loves soil additives such as compost and peat moss. Cultivate the garden bed before planting and add one-third volume of organic material to the planting site. As the plant matures, stir up the top levels of soil with a wheel cultivator and add compost regularly. Add mulch to improve water retention and keep roots cool during the hottest parts of the growing season.
Hydrangea forms flower buds before the end of summer so pruning must be timed to limit destruction of the next year's blooms. Carefully prune old wood using sharp pruning shears or loppers as soon as blooming finishes for the season. This offers an excellent time to thin the entire plant to promote branching and full foliage. Select random branches and make pruning cuts where the branch meets an adjoining branch. Do not tip prune a hydrangea.
Transplanting a large hydrangea won't harm the plant but it might hurt your back. Prepare a soil site with at least one-third organic matter tilled into the soil. Begin digging outside the dripline (edge of foliage) of the plant and work carefully into the main stem to avoid damaging roots. Hydrangea divide easily so create multiple plants from one large specimen. If you simply want another hydrangea to plant in the landscape, gently expose an inch-wide swath of bark around a low-lying branch. Pull the branch to the soil level and cover it the middle portion, leaving at least a 6-inch tip protruding from the soil. The hydrangea will root and provide a viable transplant by the following spring.
Changing Flower Color
These plants produce flowers based on soil acidity and alkaline. Gardeners can control levels to produce certain color blooms or simply let nature decide the color. To turn flowers blue, add one tablespoon of alum to one gallon of water and pour this solution on the plant at one-month intervals beginning in March. For pink flowers, mix one tablespoon of hydrated lime into a gallon of water once a month in the spring. Pour either solution at the base of the main plant stem and avoid wetting foliage.