Hydrangea, Bigleaf Hydrangea, French Hydrangea, Hortensia, Mophead Hydrangea, Pennymac, Snowball Plant
Hydrangeas are easily-grown if planted in well-drained soil and provided with regular water and some afternoon shade. For best results, the soil should be tested prior to planting. Hydrangeas perform best in slightly-acidic soil, and if blue flowers are desired, the pH of the soil must be at 5.0-5.5. If Hydrangea shrubs are purchased from a local nursery, a hole must be dug twice the width of the root ball. The plant will benefit from the addition of organic matter to the existing soil at the time of planting and should only be planted as deeply as it was in the purchased container. The soil should be well-watered, and for best results, topped with a two inch layer of bark mulch. Hydrangeas may be propagated by stem cuttings. To accomplish this, a several-inch-long stem is cut from the plant, with one or two leaves attached. The lower end is then dipped into rooting hormone powder and gently pressed into a moist growing medium until roots form.
Hydrangeas thrive in consistently-moist, fertile soil, but excellent drainage is a requirement. Although the plants flower most consistently in sun, afternoon shade is necessary to provide protection from the blaring heat. Hydrangeas should be deeply watered three times a week and perhaps even more frequently during extremely hot periods of summer. Care should be taken to apply water to the base of the plant, thus keeping the leaves and flowers dry. Staking may be necessary after a rainstorm if the plant is weighed down with blooms, causing the branches to droop.
A fertilizer higher in phosphorous will encourage flowers to form. A 15-30-15 water-soluble fertilizer may be applied once in May, and again in July, making sure to follow the directions on the product label. Hydrangeas should not be fertilized after August.
Spent blossoms should be regularly removed from Hydrangeas. The plant should be cut back by about 20 percent in order to maintain its shape. Since Hydrangeas bloom from old wood, pruning in spring or summer can hinder the formation of flowers. Only dead wood should be pruned in spring after the plant has leafed out..
Hydrangeas are not affected by any serious pests or diseases. Powdery Mildew can arise from excessively-moist conditions. If this occurs, the plant may be treated with a fungicide, according to the directions on the product label.