The limelight hydrangea (Hydrangea paniculata Limelight) is a cultivated variety of the panicle hydrangea type, which is a large hydrangea shrub or small tree that grows 10 to 20 feet tall and wide. Limelight hydrangeas bloom in creamy white and lime-colored flower blossoms that are large, showy and tinged with yellow in autumn. The limelight hydrangea can be planted as an individual specimen, as part of a hedge or privacy screen, or even in a container. The limelight hydrangea is cold hardy and grows best in USDA hardiness zones 3 through 8, where winter temperatures can dip down to minus 35 degrees Fahrenheit.
Water your limelight hydrangeas deeply and thoroughly to soak the soil around the roots once each week during the summer when rainfall is less than 1 inch. Keep the soil constantly and evenly moistened at all times while the hydrangeas are actively growing.
Spread a 1-inch-thick layer of organic compost on the ground around the limelight hydrangeas once each year in spring. Spread the compost to the entire canopy area beneath the hydrangea.
Apply a 2- to 4-inch-thick layer of bark or wood chip mulch on the ground around the limelight hydrangea to keep weeds at bay and preserve soil moisture. Keep the mulch about 2 inches away from the trunks.
Prune your limelight hydrangea during summer and autumn to remove faded flower blossoms. This will keep the hydrangea healthy and encourage it to grow new blooming stems.
Cut back your limelight hydrangea by about half its size in mid-fall, when the growing season ends. Doing this will encourage the hydrangea to grow back larger and with more flowers the next spring.