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How to Grow a Hydrangea Shrub

Hydrangea Bush - Pink Flowers
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Hydrangea spp.
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Planting, Growing, and Pruning Hydrangeas

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With immense flower heads, hydrangeas flaunt an old-fashioned charm from summer to fall. See our Hydrangea Growing Guide for information on how to plant and care for these flowering shrubs.

About Hydrangeas

Unrivaled in the shrub world for their beautiful flowers, these elegant perennial plants are easy to cultivate, tolerate almost any type of soil, and produce abundant blooms. Colors beguile with clear blue, vibrant pink, frosty white, lavender, and rose blossoms—sometimes all blooming on the same plant! 

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

Enjoy this ode to the beauty of hydrangeas and learn how to grow hydrangeas in our guide below.

Planting

Most hydrangeas prefer partial sun with full sun in the morning, followed by some afternoon shade. This is especially true for the Bigleaf hydrangea (H. macrophylla). Some varieties are more tolerant of full sun. Most hydrangeas will thrive in fertile, well-draining soils that receive plenty of moisture. Add compost or aged manure to enrich poor soil.

When to Plant Hydrangeas

Autumn is the best time to plant hydrangeas, followed by spring planting. Plan to plant in the spring after the last frost or in the fall before the first frost. The idea is to give this shrub plenty of time to establish a healthy root system before the heat of summer or the extreme chill of winter, which makes the cooler shoulder seasons the best times to plant.

Plant the shrubs in the early morning or late afternoon. It’s generally cooler, and the plant is less likely to wilt with the extreme heat.

How to Plant Hydrangeas

  • Space hydrangeas anywhere from 3 to 10 feet apart, depending on the type. Always space plants based on their expected size at maturity!
  • Gently remove the hydrangea from its container and inspect the root ball, snipping off any dead or rotting parts and teasing free the roots if the plant is especially root-bound.
  • Dig a hole as deep as the root ball and 2 to 3 times as wide. The base of the plant (where the stem meets the soil) should be level with the top of the planting hole.
  • Set the plant in the hole and half-fill it with soil. Water generously. After the water is absorbed, fill the rest of the hole with soil and water again.

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. Find a new branch on a well-established hydrangea—a branch that has not flowered and bears three or more pairs of leaves. (New growth will appear lighter in color than old, and the branch will not be as rigid.)
  2. Cut 5 to 6 inches from the tip of the branch. Discard the bottom piece.
  3. If the tip cutting has at least two pairs of leaves, remove the lowest pair of leaves flush to the stem or at the node. If the remaining leaves are large, cut them in half, removing the tip half. Dust the cutting’s end with rooting hormone and, if desired, an anti-fungal plant powder. This will encourage rooting and discourage rotting.
  4. Fill a small pot with moistened potting mix. Plant the cutting, sinking it up to the first pair of remaining leaves. Water lightly to eliminate any air gaps around the stem. Cover the pot and the cutting loosely with a plastic bag (to maintain humidity). If necessary, use chop- or kebab sticks to prop up the bag so that it does not touch the leaves; if it touches the leaves, they might rot. Place in a warm area, sheltered from direct sunlight and wind. Water when the top layer of soil is dry.
  5. After a week or so, gently pull on the cutting. If you feel resistance, roots have formed. If there is no resistance, check for rotting.

Layering Hydrangeas

For bigleaf hydrangeas, in summer, dig a trench next to the plant, near a branch that easily reaches beyond the trench. Where the branch contacts the soil, remove an inch of the outer bark all around it. Bury the bared portion, pinning it with a florist’s pin or a gentle weight, leaving 6 to 12 inches of the end of the branch tip uncovered. Water regularly. In early spring, the branch should be ready to remove from the mother plant and transplant!

Growing

Watering Hydrangea Shrubs

  • For the first two years after planting and during any drought, be sure your hydrangeas get plenty of water. If possible, water in the morning to prepare hydrangeas for the heat of the day and to avoid disease.
  • Water at a rate of 1 inch per week throughout the growing season.  Deep soaks three times a week (with a soaker hose or the like that keeps moisture off flowers and leaves) encourage root growth more than frequent sprinkles.
  • All varieties benefit from consistent moisture, but bigleaf and smooth hydrangeas require more water. If the soil is too dry, leaves will wilt, and flowering will be hampered.
  • Add organic mulch underneath your hydrangeas to help keep the soil moist and cool, add nutrients over time, and improve soil texture.

Fertilizing Hydrangeas

Hydrangeas in rich soil seldom need fertilizer: Too much encourages leafy growth over blooms. The best way to determine your fertility needs is by using a soil test.

Apply fertilizer based on your specific hydrangeas. Each variety has different needs and will benefit from different application timing.

  • Bigleaf hydrangeas can benefit from several light fertilizer applications in March, May, and June.
  • Oakleaf and panicle hydrangeas do best with two applications in April and June.
  • Smooth hydrangea plants only need fertilization once, in late winter.

Winter Protection

  • In the fall, cover plants to a depth of at least 18 inches with bark mulch, leaves (not maple), pine needles, or straw. 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.)

Pruning Hydrangeas

Many of our readers’ questions involve pruning hydrangeas. And no wonder—it’s confusing and depends on the variety of hydrangea. Luckily, as long as you know which type you’ve got, it’s easy to figure out what sort of pruning technique to employ. (The more common garden hydrangea shrub is the big leaf variety) Learn the essentials below.

Hydrangea TypeWhen to PruneWhere Flowers Appear
Bigleaf (H. macrophylla)Summer, after floweringOn old growth
Oakleaf (H. quercifolia)Summer, after floweringOn old growth
Panicle (H. paniculata)Late winter, before spring growthOn new growth
Smooth (H. arborescens)Late winter, before spring growthOn new growth
Mountain (H. serrata)Summer, after floweringOn old growth
Climbing (H. anomala ssp. petiolaris)Summer, after floweringOn old growth

Bigleaf (H. macrophylla)Oakleaf (H. quercifolia), Mountain (H. serrata), and Climbing hydrangeas (H. anomala spp. petiolaris) 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 afterward in 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 the dead stems in the spring.

Panicle (H. paniculata) and Smooth (H. arborescens) hydrangeas are pruned BEFORE flower buds are formed. These varieties bloom 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 types.

How to Change the Color of Hydrangea Flowers

The colors of hydrangea flowers can be changed, but not instantly. Color correction takes weeks or more, and not every cultivar is changeable: White flowers are not affected by soil pH, the condition that imparts the blue and pink hues. Some bigleaf hydrangeas— especially mophead and lacecap types— and mountain hydrangea (I) 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 6.0 produce pink flowers. Do a soil test to determine the existing pH and amend as indicated to change it.

A plant should be at least two years old before undergoing a pH change; this will 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.

See How to Change the Color of Hydrangea Flowers for more information.

pink, purple, and blue Hydrangea colors

Harvesting

Cut fully mature hydrangea flowers in the morning after you have watered the plant.
Immediately place fresh stems in cold water to prevent wilting. 

  • Recut the woody stems at a slant underwater. 
  • Remove the lower leaves on the stems. 
  • Arrange them in a vase and place them in a cool location, out of direct sunlight.
  • Check the water level and quality daily. Change the water if it becomes cloudy. 
  • Mist the blooms with water. Soak wilting blooms in cool water for 10 to 15 minutes to revive them.

Bigleaf Hydrangea (mophead)

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 them 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.

Here are four alternative ways to dry and preserve your flowers.

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Wit and Wisdom

  • The word “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.

Pests/Diseases

Pests are rare but can appear when plants become stressed. Protect against pests and disease by choosing resistant cultivars, and follow our tips on caring for your hydrangea.

Diseases: Botrytis blight, southern blight, bacterial leaf spot, fungal leaf spot, powdery mildew, Armillaria root rot, Phytophthora crown and root rot, Pythium root and stem rot,
Rhizoctonia root and stem rot, rust, and viruses. 

Pests: aphids, foliar nematodes, root-knot nematodes, stem and bulb nematodes, and spider mites.

Hydrangeas Not Blooming? 5 Reasons Why

A more common problem is hydrangeas that don’t bloom. Here are five common reasons your hydrangea isn’t flowering:

  1. As discussed above, you need to know the variety of hydrangea, as some types are pruned before flowering, and some are pruned afterward. Without knowing this, you risk cutting off its buds (aka blooms).
  2. There’s a reason “hydra” is in the word “hydrangeas.” These plants need soil that is always moist (but not wet). Water correctly.
  3. The perfect location for a hydrangea is a place with a few hours of direct sun in the morning and dappled sunlight in the afternoon. Too little sunlight or overly intense sunlight affects flowering.
  4. Are you getting lush green leaves without blooms? Then, check your fertilizer. Do not use a fertilizer high in nitrogen; use one that’s high in phosphorus (P) in the early spring and mid-summer.
  5. Weather and climate is an issue. You must pick a variety that works for your climate zone. And even then, a late spring frost that happens right when the plant is budding could kill the buds. If a frost is forecasted, cover hydrangeas the shrubs with a sheet until morning. 
About The Author

Catherine Boeckmann

Catherine Boeckmann loves nature, stargazing, and gardening so it’s not surprising that she and The Old Farmer’s Almanac found each other. She leads digital content for the Almanac website, and is also a certified master gardener in the state of Indiana. Read More from Catherine Boeckmann

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