Hydrangeas have a reputation of being hard to grow because their needs are specific, and they react poorly to bad growing conditions. Their blooming flowers are showy and abundant when they receive the care they require. Their flowers bloom in pinks, blues, lavenders and whites, according to the acidity of the soil they are grown in. Taking a few simple precautions about growing conditions ensures dependably beautiful hydrangeas.
The word "hydrangea" comes from Greek words that mean "water" and "vessel." Hydrangea plants need moisture and fade quickly without it. There are between 70 and 75 species of hydrangea, and they have been cultivated most extensively in eastern Asia. Hydrangea roots are a staple in traditional Chinese medicine and are currently being researched for their positive effect on diseases such as multiple sclerosis, arthritis and diabetes.
Hydrangeas are either evergreen or deciduous.They are deciduous in all temperate growing zones.The newer variety "Oakleaf Hydrangea' has leaves that turn red in the fall before they drop. They may be hard to grow if not given enough shade. Hydrangeas are a shrub characterized by large, flat leaves that easily wilt in hot sun exposure. The plant grows from 3-to-9 feet tall and produces globe-shaped flowers during the summer months. The large, showy flowers are made up of smaller blooms with a simple four-petal structure.
Care for hydrangeas may be considered hard because they are subject to insect pests such as aphids, scale and two spotted spider mites. Leaf spot, powdery mildew and rust spot are diseases that can affect hydrangea. Use of beneficial insects such as preying mantis and ladybugs reduces the aphid problem. Inter-planting hydrangea beds with onions, garlic, geranium, nasturtiums and French marigolds helps repel insect pests. Insecticidal soap used as a spray to kill aphids is also effective. Spray tops and underside of leaves as a preventative or when there is an insect infestation.
Watering issues sometimes make hydrangeas hard to grow. They are woodland shrubs that prefer high moisture content in the soil. Too little water causes leaf wilt. Plants need to be watered regularly and thoroughly to perform their best. They can be hard to grow in areas with heavy, clay-like soil that does not allow the hydrangea roots to grow deep. Organic compost used as a soil amendment addresses this problem.
It may be difficult to grow abundant flowers on hydrangea plants if they are not pruned each year. The flowers develop on old wood, wood produced in the previous year's growth. Well-pruned hydrangeas are cut back to 1 to 3 buds on each branch. Prune hydrangeas in August when buds have started to form. Paniculata and aborescens hydrangeas bloom on new wood and should be pruned in spring, cutting the main structure back to 1 foot high. In harsh winter areas the plants need protection. They should either be dug up and kept in a protected indoor area or covered with a box open at both ends. Fill the box with dirt to further protect the plants during very cold conditions.