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. Colors also beguile with clear blues, vibrant pinks, frosty whites, lavender, and rose—sometimes all blooming on the same plant!

The flowers of Bigleaf hydrangeas can change color based on the soil pH, which affects relative availability of aluminum ions. 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.

Unrivaled in the shrub world, these elegant ladies are easy to cultivate, tolerate almost any soil, and produce flowers in mid-summer through fall (when little else may be in bloom). Hydrangeas are excellent for a range of garden sites from group plantings to shrub borders to containers.

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 B igleaf hydrangeas (see Recommended Varieties).
  • 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

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 cold regions, 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 will break down too quickly.)

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.

  • Bigleaf hydrangeas (Hydrangea macrophylla)—especially Mophead and Lacecap varieties—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.
  • To get blue flowers, add sulfur or peat moss to the soil.
  • To get pink to light red flowers, add ground limestone around the plant.
  • White flowers are not affected by pH.
  • In the fall, hydrangea flowers will naturally fade and dry, often to a combination of pink and green or tan. This is simply the aging process, which cannot be reversed.
  • Note that hard water can affect the flower color, turning blue flowers more pinkish, so use rainwater to water your hydrangeas, when possible.

Bigleaf Hydrangea (mophead)

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. 

How to Prune Common Hydrangeas

  • The most common garden hydrangea shrub is the Bigleaf variety, Hydrangea macrophylla. One type of Bigleaf is the “Mophead” with big, snowball-size blooms. The other type of Bigleaf is the “Lacecap” with the pretty flowers almost hanging down from a flat center of tiny blooms. 
  • 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.

How to Prune 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:

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

How to Use Hydrangeas in a Bouquet

  • Place the freshly cut hydrangea stems immediately into cold water to avoid wilting.
  • Recut the woody stems at a slant under water. Remove lower leaves on the stems.
  • Arrange the stems in a vase and place in a cool spot. 
  • Check the water in the vase daily and mist the blooms with water. 
  • 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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