Hydrangeas are perennial shrubs grown for their ornamental flowers, ease of cultivation and compact growth habit. The name hydrangea is derived from the Greek words "hydra" and "angeon," meaning water vessel. The plants flower from summer to early fall, producing multiple blossoms in shades of pink or blue, depending on the acidity of the soil at the planting site. Native to temperate regions around the world, hydrangeas are cultivated throughout the United States with only basic care.
Plant hydrangeas during early spring in a location that receives bright morning sun and partial afternoon shade when temperatures peak. Spread a 2-inch layer of organic compost over the site and use a garden spade to work it into the soil to increase fertility before planting.
Dig a hole in the soil of equal depth and 2 feet wider than the hydrangea's root ball. Insert the root ball into the hole and gently cover with soil. Water the plant lightly to compact the soil and collapse any air pockets. Space hydrangeas 4 to 6 feet apart.
Apply a 3-inch layer of mulch over the ground surrounding hydrangeas to insulate the soil, deter competitive weeds and improve moisture retention. Begin the layer at least 3 inches from the crown of the hydrangea plant to allow air circulation and minimize the risk of fungal disease.
Feed hydrangeas three times per year, once in March, once in May and once in July, using a low-phosphorous 12-4-8 NPK fertilizer. Water immediately after application to dissolve the fertilizer into the soil. Apply according to the instructions on the package for the best results.
Prune hydrangeas once a year during late winter, just before new growth begins. Use pruning shears to remove 1/3 of the old wood from the bottom of the plant to encourage vigorous new growth the following spring.