Unlike most hydrangea varieties, endless summer blooms until the first frost, producing flowers on new growth and old wood. Reaching up to 5 feet in height in a single season, the perennial shrub's fast growth and long blooming period make it a popular addition to gardens across the country. Because of its ability to produce new blossoms without the previous year's growth, endless summer hydrangea also thrives in cooler climates where other varieties may fail. Like other hydrangeas, flower color depends upon soil acidity, and gardeners can change the color of blooms by amending the soil. Hardy to USDA zone 4, the plant requires minimal care to thrive and flower throughout the United States.
Plant endless summer hydrangea during late spring in a location that receives at least six hours of bright sunlight each day and has well-drained, rich soil. Space endless summer hydrangea plants 7 to 10 feet apart.
Water thoroughly once each week to provide plenty of moisture for the roots. Allow the soil to dry slightly between each application. Pour the water directly over the soil to avoid wetting the foliage and increasing the plant's vulnerability to disease.
Feed endless summer hydrangea plants once per year during late spring or early summer using a slow-release 10-30-10 NPK fertilizer. Follow the directions provided on the package for the best results.
Prune once per year during late winter to keep the plant visually appealing, healthy and growing in a compact habit. Use pruning shears to cut back any excessively long growth and remove any damaged or diseased limbs.
Apply a 2- to 3-inch layer of mulch over the soil surrounding endless summer hydrangeas during late fall, just before the first frost of winter, to insulate the soil and protect the crown and roots from cold damage. Remove the mulch during early spring after the threat of frost has passed.