What Does a Hydrangea Bush Look Like in Winter?
The huge flower heads of a hydrangea bush (Hydrangea spp.) can fill a landscape with vibrant pops of blue, pink, or white throughout summer. Typically hardy to USDA zones 4 to 9, many hydrangea varieties can survive a mild winter without special care, but their springtime growth and color benefit from attentive watering, pruning, fertilizing, mulching and weathering during the chilly season. Their stems remain visible during winter, and old flower heads (if not pruned) will turn brown.
Hydrangea flower heads turn dry and brown in the fall and will remain that way throughout winter if not removed. Hydrangeas also lose their leaves during fall, but the brown stalks remain upright unless pruned back.
Preparing a Hydrangea Bush for Winter
Preparing a hydrangea bush for winter starts in summer with a final application of a 10-10-10 fertilizer (2 cups per 100 square feet according to Clemson University) or a 6-inch layer of compost in July or August. Applying fertilizer later in the year could stimulate new growth on the hydrangea instead of encouraging dormancy, as could pruning the stems in fall or winter.
Next, maintain a regular deep-watering routine. For low-maintenance hydrangea care, plan to leave the hose trickling at the base of the plant for one hour every week until the ground freezes and water cannot pass through the soil. However, as much as hydrangeas need water, Oregon State mentions that it's possible to drown them in too much of it. If the soil has a high clay content or is otherwise slow to drain, overwatering will cause the roots to remain saturated, and the hydrangea's leaf edges will begin to turn brown.
The final task essential for preparing a hydrangea for winter is to keep it warm. According to Clemson University, hydrangeas won't bloom well in the spring if they experience injuries from severe frosts, among other possible causes. Keep their roots warm with a loose layer of leaves or straw, and completely cover the stems in a burlap blanket in zone 4 or any time unusually cold temperatures are in the forecast.
Don't Prune Hydrangeas in Winter
Winter is not an ideal time to prune hydrangeas, since it can stress the plant or possibly stimulate growth in the wrong season. Instead, prune in the late summer or fall after the last blooms have erupted.
Look for two distinct types of wood on hydrangeas: old wood and new wood. Old wood is last year's growth and, on some hydrangea types, the only wood that supports new buds. However, at the end of the season, this wood can be removed to make more room for the new wood, which had no flowers this year but will support flowers next year. New wood has a more vibrant color and elastic texture, whereas old wood looks duller and more dry.
Prune again in the spring to remove stems that died during winter frosts. You can tell that a stem is dead by carefully scraping off its outer layer. A stem that is alive will have tinges of green, but a dead stem will have no color at all. You can also look for evidence of buds on the stems. Using sharp pruning shears, trim at a 45-degree angle a few inches above the last bud.
If you feel a little nervous about pruning your hydrangeas, know that you don't have to prune them at all. The University of Maryland recommends simply removing the old flower heads and waiting until spring or summer to see exactly which stems are beyond old (they'll have no leaves at all) and can be safely removed without affecting this year's blooms.
Cathy Habas has been a full-time freelance writer since 2014. She graduated from Indiana University Southeast with a Bachelor's degree in English. She enjoys writing content that helps homeowners feel motivated and confident in handling projects around the home. Her work has been published around the web, including on home improvement sites like Ron and Lisa.