How to Care for a Hydrangea
- For the first year or two after planting and during any drought, be sure hydrangeas get plenty of water. Leaves will wilt if the soil is too dry.
- If your soil is rich, you may not need to fertilize hydrangeas. If your soil is light or sandy, it’s best to feed the plants once a year in late winter or spring. Too much fertilizer encourages leafy growth at the expense of blooms. Learn more about soil amendments.
- In the fall, cover plants to a depth of at least 18 inches with bark mulch, leaves, pine needles, or straw in the fall. If at all possible, cover the entire plant, tip included, by making cages out of snow fencing or chicken wire, and loosely filling the cages with leaves. (Do not use maple leaves, as they tend to mat when wet and can suffocate the plant.)
How to Change the Color of Hydrangea Flowers
It is possible to change the flowers’ colors, but not instantly. Color correction takes weeks—even months. Wait until the plant is at least 2 years old to give it time to recover from the shock of its original planting. Also note that it’s easier to change blue flowers to pink than pink to blue.
It’s not every hydrangea that changes color. The color of some Bigleaf hydrangeas (H. macrophylla)—especially Mophead and Lacecap types—and H. serrata cultivars change color based on the soil pH.
Acidic soils with a pH of less than 5.5 produce blue flowers; soils with a pH greater than 5.5 produce pink flowers. White flowers are not affected by pH.
See How to Change the Color of Hydrangea Flowers for more information.
How to Prune a Hydrangea
Many of our readers’ questions are about pruning a hydrangea. And no wonder—it’s confusing, and all depends on the variety of hydrangea.
Pruning Common Hydrangeas
The most common garden hydrangea shrub is the Bigleaf variety, Hydrangea macrophylla. (See more below.)
Bigleaf (H. macrophylla), as well as Oakleaf (H. quercifolia), are pruned AFTER the flowers fade in the summer. These varieties bloom on the previous season’s stems (“old wood”).
- Flower buds actually form in the late summer and flower afterwards the following season, so avoid pruning after August 1.
- Only cut away dead wood in the fall or very early spring.
- To prune, cut one or two of the oldest stems down to the base to encourage branching and fullness.
- If the plant is old, neglected, or damaged, prune all the stems down to the base. You’ll lose the flowers for the upcoming season, but also rejuvenate the plant for future years.
- It’s best not to deadhead (remove faded blooms) on the big Mopheads; leave them over the winter and cut them back in early spring (to the first healthy pair of buds). It’s fine to deadhead the Lacecaps; cut down to the second pair of leaves below the flower head.
- When growing H. macrophylla (and H. serrata) varieties in Zones 4 and 5, do not prune unless absolutely necessary, and then do so immediately after blooming. Otherwise, remove only dead stem in the spring.
Pruning Other Hydrangeas
- Panicle (H. paniculata) and Smooth (H. arborescens) hydrangeas are pruned BEFORE flower buds are formed. These varieties blossom on the current season’s stems (“new wood”).
- Prune in the late winter when the plant is dormant. This means that if the buds are killed during the winter, the plant will produce new buds in the spring which will produce blooms.
- In general, prune only dead branches, and do not prune to “shape” the bush.
Read more about how to prune hydrangea varieties.