Hydrangeas (2024)

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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 poorsoil.

When to PlantHydrangeas

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 toplant.

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

How to PlantHydrangeas

• Space hydrangeas anywhere from 3 to 10 feet apart, depending on the type. Always space plants based on their expected size atmaturity!
• 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 rootbound.
• 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 plantinghole.
• 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 wateragain.

How to Grow Hydrangeas fromCuttings

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

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 asrigid.)
2. Cut 5 to 6 inches from the tip of the branch. Discard the bottompiece.
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 discouragerotting.
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 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 isdry.
5. After a week or so, gently pull on the cutting. If you feel resistance, roots have formed. If there is no resistance, check forrotting.

LayeringHydrangeas

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 andtransplant!

WateringHydrangea

• For the first two years after planting and during any drought, be sure hydrangeas get plenty of water. If possible, water in the morning to prepare hydrangeas for the heat of the day and to avoiddisease.
• 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 frequentsprinkles.
• All varieties benefit from consistent moisture, but bigleaf and smooth hydrangeas require more water. Leaves wilt, and flowering will be hampered if the soil is toodry.
• Add organic mulch underneath your hydrangeas to help keep the soil moist and cool, add nutrients over time, and improvesoiltexture.

FertilizingHydrangea

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 soiltest.

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

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

WinterProtection

• 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 theplant.)

PruningHydrangea

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 essentialsbelow.

Bigleaf (H. macrophylla),Oakleaf(H. quercifolia), Mountain (H. serrata), and Climbing hydrangeas (H. anomala spp. petiolaris)are prunedAFTERthe flowers fade in the summer. These varieties bloom on the previous season’sstems(“oldwood”).

• Flower buds actually form in thelate summer and flower afterward in the following season, so avoid pruning after August1.
• Only cut away dead wood in the fall or very earlyspring.
• To prune, cut one or two of the oldest stems down to the base to encourage branching andfullness.
• If the plant is old, neglected,or damaged, prune all thestems down tothe base. You’ll lose the flowers for the upcoming season, but also rejuvenate the plant for futureyears.
• It’s best not to deadhead (remove fadedblooms) 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 flowerhead.
• 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 thespring.

Panicle (H. paniculata)and Smooth (H. arborescens) hydrangeas are pruned BEFORE flower buds are formed. These varietiesbloom on the current season’s stems(“newwood”).

• Prune in the latewinter 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 produceblooms.
• In general, prune only dead branches, and do not prune to “shape” thebush.

Read more about how to prune hydrangea types.

How to Change the Color of HydrangeaFlowers

Hydrangea flowers’ colors 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 soilpH.

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 changeit.

A plant should be at least 2 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 toblue.

See How to Change the Color of Hydrangea Flowers for moreinformation.

For a more detailedoverview of the many types of hydrangeas, check out Hydrangea Varieties for Every Garden.

There are two main groups ofhydrangeas:

Group 1: Plants that Bloom on New Growth (This Year’sStems)

The following hydrangeas, which form their buds in early summer on new growth, will flower reliably each year, requiring no specialcare.

• Panicle hydrangeas (Hydrangeapaniculata)
  • ‘Grandiflora’ and ‘PeeGee’ are large old-fashioned, floppy varieties; ‘Tardiva’, ‘White Moth’, and ‘Pee Wee’ fit the scale of small gardens. ‘Limelight’ produces cool-green flowers and grows to a height of 6 to 8feet.
• Smooth hydrangeas (H. arborescens)
  • ​​​​Look for the cultivars H. arborescens ‘Grandiflora’ and ‘Annabelle’, which produce many large (up to 14 inches across), tight, symmetrical blooms in latesummer.

Group 2: Plants that Bloom on Old Growth (Last Year’sStems)

If you live in Zone 8 or warmer, choose plants from this group. Gardeners in cool climate zones will find many of them a challenge, because they set flower buds in the fall. Although hardy to Zones 4 and 5, the buds are prone to damage by an early frost in fall, a late frost in spring, or excessively coldtemperatures when dormant in winter. This, along with untimely pruning, can result in inconsistent or noflowering.

• Oakleaf hydrangeas (H. quercifolia)
  • You can expect an exceptional fall color from ‘Snow Queen’, ‘Snow Flake’, and‘Alice’.
• Bigleaf hydrangeas (H. macrophylla)
  • We love ‘All Summer Beauty’ (mophead), which has profuse, dark blue flowers—which turn pinker insoils with near neutral pH.If buds are winter-killed, the plant will form new ones in spring and stillbloom.
  • ‘Nikko Blue’ (mophead) is vigorous, with large, rounded, blueflowers.
  • ‘Blue Wave’ (lacecap) produces rich blue to mauve or lilac-blue to pinkflowers.
  • ‘Color Fantasy’ (mophead) has reddish or deep purple flowers and shiny, dark green leaves. It grows to about 3 feettall.
• Mountain hydrangeas (H. serrata)
  • ‘Bluebird’ and ‘Diadem’ are early bloomers. In acidic soil, ‘Preziosa’ produces blossoms of an extraordinary blend of pale shades of blue, mauve, violet, andgreen.
• Climbing hydrangeas(H. anomala ssp.Petiolaris)
  • ‘Firefly’ boasts variegatedfoliage.

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

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

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

1. Cut the flower heads when the flowers have matured and developed a paperyconsistency.
2. Remove leaves from stems, and hang them upside down in a warm, dry, dark, airyroom.
3. When completely dry (usually a couple of weeks), store in a dry location out of directsunlight.
4. To enhance flower color, spritz dry flowers with diluted fabricdye.

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