Growing Hydrangeas

How to Plant, Grow, and Prune Hydrangeas

Hydrangea Bush - Pink
Pixabay

With immense flower heads, hydrangeas flaunt an old-fashioned charm that is hard to resist. Unrivaled in the shrub world for beautiful flowers, the elegant ladies are easy to cultivate, tolerate almost any soil, and produce abundant blooms. Colors beguile with clear blues, vibrant pinks, frosty whites, lavender, and rose—sometimes all blooming on the same plant! 

Hydrangeas are excellent for a range of garden sites from group plantings to shrub borders to containers. Varieties abound (every year, it seems, breeders present us with more options!), and gardeners’ expectations of bloom size and color are boundless. To know how your hydrangea will grow, pay attention to the types, defined below. When you know what to expect, delights will be magnified.

“How to change hydrangea flower color” is a common question from Almanac readers. Yes, the flowers of Bigleaf hydrangeas can change color based on the soil pH! Blues are best grown in acidic soil; pinks and reds do best in alkaline or neutral soil. We get into more detail below.

Planting

  • Most hydrangeas thrive in rich, porous, somewhat moist soils. Add compost to enrich poor soil.
  • They prefer full sun in the morning, with some afternoon shade; however, many will grow and bloom in partial shade. This is especially true for the Bigleaf hydrangeas.
  • Plant in spring or fall.
  • Dig a hole as deep as the root ball and 2 to 3 times as wide.
  • Set the plant in the hole and fill it half full with soil. Water. After water is drained, fill the rest of the hole with soil.
  • Water thoroughly.
  • Space multiple hydrangeas about 3 to 10 feet apart.

Pink hydrangea flowers

How to Grow Hydrangeas from Cuttings

Hydrangeas can easily be grown from cuttings. They root readily and the process makes for a great lesson in propagation. Here’s how to do it:

  1. On a well-established hydrangea, find a branch that is new growth and that has not flowered. New growth will appear lighter in color than old growth, and the stem will not be as rigid. 
  2. From the tip of the branch, move 4 to 5 inches down and make a horizontal cut. Make sure that there are at least 3 to 4 pairs of leaves on your cutting.
  3. Remove the lowest pair of leaves from the cutting, trimming them flush to the stem. Roots grow more easily from these leaf nodes, so if you can afford to remove more than one pair of leaves, do so. Be sure to keep at least 2 pairs of leaves at the tip end of the cutting, though. 
  4. If the remaining leaves are quite large, cut them in half, removing the tip-half. This prevents the leaves from hitting the sides of the plastic bag you will place over the cutting later on (to keep the humidity up).
  5. (Optional) Dust the leafless part of the stem with rooting hormone and an anti-fungal powder for plants (both available at a local hardware or garden store). This will encourage rooting and discourage rotting.
  6. Prepare a small pot and fill it with moistened potting mix. Plant the cutting in the soil, sinking it down to the first pair of remaining leaves. Water lightly to get rid of any air gaps around the stem.
  7. Cover the entire pot loosely with a plastic bag. Make sure the bag isn’t touching the leaves of the cutting, otherwise the leaves can rot. (Chopsticks or something similar can be used to prop up the bag and keep it off the leaves.)
  8. Place the pot in a warm area that’s sheltered from direct sunlight and wind.
  9. Check on your cutting every few days to make sure that it isn’t rotting and only water again once the top layer of soil is dry. With luck, the cutting should root in a few weeks! (Check by gently pulling on the cutting; if you feel resistance, roots have formed.)

Care

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.

Hydrangea colors

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.

Pests/Diseases

Click links for common pest pages:

Harvest/Storage

How to Cut and Store Dried Flowers

Use dried hydrangea flowers to create a wreath or other decorations around the house:

  1. Cut the flower heads when the flowers have matured and developed a papery consistency.
  2. Remove leaves from stems, and hang upside down in a warm, dry, dark, airy room.
  3. When completely dry (usually a couple of weeks), store in a dry location out of direct sunlight.
  4. To enhance flower color, spritz dry flowers with diluted fabric dye.

Bigleaf Hydrangea (mophead)

How to Use Hydrangeas in a Bouquet

  1. Place the freshly cut hydrangea stems immediately into cold water to avoid wilting.
  2. Recut the woody stems at a slant under water. Remove lower leaves on the stems.
  3. Arrange the stems in a vase and place in a cool spot. 
  4. Check the water in the vase daily and mist the blooms with water. 
  5. Soak wilting blooms in cool water for 10 to 15 minutes to revive them.

Recommended Varieties

Wit & Wisdom

The name hydrangea is derived from the Greek words hydor meaning water and angeion meaning vessel, referring to the plant’s seed pods, which look like small water jugs.

In the language of flowers, hydrangeas symbolize gratitude for being understood, or frigidity and heartlessness. See more flower meanings.

Planting Times

Growing Hydrangeas

Botanical Name

Hydrangea

Plant Type Shrub
Sun Exposure Full Sun, Part Sun
Soil Type Any
Soil pH Acidic, Neutral, Neutral to Slightly Alkaline, Slightly Acidic to Neutral
Bloom Time Summer, Fall
Flower Color Blue, Green, Pink, Purple, Red, White
Hardiness Zones 3, 4, 5, 6, 7, 8, 9
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