How to Grow and Care for Hydrangeas

Common Names	Hydrangea, hortensia
Botanical Name	Hydrangea spp.
Family	Hydrangeaceae
Plant Type	Shrub
Mature Size	2-20 ft. tall, 2-6 ft. wide
Sun Exposure	Full, partial
Soil Type	Moist, well-drained
Soil pH	Acidic, neutral, alkaline
Bloom Time	Summer, fall
Flower Color	White, blue, pink, red, purple, green
Hardiness Zones	5—9 (USDA)
Native Area	Asia, North America
Toxicity	Toxic to people, pets

Hydrangea Care

Here are the main care requirements for taking care of hydrangea flowers:

• Plant in well-draining soil with plenty of organic matter.
• Water your hydrangeas regularly to keep them consistently moist, especially in hot and dry weather.
• Fertilize hydrangeas once in the spring.
• Prune hydrangeas according to the hydrangea’s species and the time of year when it sets buds.

Planting

Plant a hydrangea in the late spring or early fall so the roots can establish themselves before the first frost. Dig a hole two times as wide as the root ball and make sure it sits at the same depth it did in the nursery pot and water deeply.

Light

Hydrangeas do well in the partial shade with morning sun and afternoon shade. Too much shade can reduce flower output. They will also thrive in full sun but might need extra water on hot summer days.

Soil

Fertile humus-rich and moist soil is best for hydrangeas. Add compost to the soil to add nutrients and retain moisture. Control bloom color by adjusting the soil pH. Acidic soil (pH of 6 or lower) produces blue flowers and neutral to alkaline soil (pH of 7 or higher) produces pink blooms.

Water

Hydrangeas need a deep drink of water one to two times a week during the growing season. Stick your finger about four inches into the ground and water if it feels dry. Saturate the soil but do not leave it soggy. Light watering is insufficient, because the water will not reach the root system.

Cut back on supplemental watering after heavy rainfall. Increase the amount of water you give hydrangeas during hot weather, but make sure they’re not sitting in soggy soil.

Temperature and Humidity

Hydrangeas prefer fairly mild temperatures. In areas with bitterly cold winters, dieback can be a problem if the hydrangea is located in an unprotected area or one that receives too much winter sun.

Hydrangeas prefer moderate to high humidity and dry climates can cause their leaves to become brown and dry.

Fertilizer

Use balanced 10-10-10 fertilizer (NPK) or fertilizer for flowering shrubs in the spring, but do not fertilize hydrangeas in the summer.

If your soil is nutrient-rich, you won’t have to fertilize your hydrangeas. If hydrangeas are given too much high-nitrogen fertilizer, the foliage will be full and lush but with fewer blooms.

Types of Hydrangea

Of the many species of hydrangea, the various cultivars are commonly used as ornamental shrubs. Some of these hydrangea species bloom on new growth, while others bloom on old growth. Two of the most popular cultivars include:

• ‘Limelight’:H. paniculata This panicle hydrangea grows 6 to 8 feet tall and needs plenty of sun to grow strong stems to support the large, cone-shaped creamy white to dusty rose flowers. This hydrangea blooms on new wood.
• H. macrophylla ‘Endless Summer’: The ‘Endless Summer’ hydrangea label includes several cultivars with rounded mop head blooms in pink, purple. blue, red, or white. This plant handles partial shade well and blooms on both new and old wood.

Species of hydrangeas include:

• H. paniculata: Commonly called panicle hydrangea, cone-shaped blooms start white, gradually change to light pink, and mature to darker pink. This plant grows quite large if left unpruned, up to 15 to 20 feet tall and wide. This species blooms on new stem growth.
• H. macrophylla: Also known as bigleaf, mophead, or lacecap hydrangea, this species grows 6 to 10 feet tall and wide. Acidic soil produces blue blooms and alkaline soil produces pink blooms. Buds for the following year are set in midsummer through fall.
• H. arborescens: Known as smooth hydrangea, this shrub reaches around 3 to 5 feet tall and wide and produces white to pink flowers. Buds are set on new stems in spring.
• H. quercifolia: Commonly called oakleaf hydrangea, this plant reaches around 7 feet tall and wide with white to purplish-pink flowers. Buds are set in midsummer through fall.

Pruning

If you don’t prune hydrangeas, they will look tangled over time and lose their vigor. Train taller hydrangea shrubs, like limelight and other panicles, into small flowering ornamental trees with single trunks.

The right time to prune many hydrangeas varies, according to the species and if its buds set on new or old wood. “New wood” refers to the current year’s stems, and “old wood” refers to the previous year’s stems.

Old Wood

Hydrangeas that bloom on old wood include bigleaf, lacecap, mopheads, and oakleafs. Prune these bushes for revitalization when they are over five years old. Cut them by a third (not to the ground) in the summer after they bloom but not in the fall because they set buds in August and September.

New Wood

Hydrangeas that bloom on new wood include smooth (such as H. arborescens ‘Annabelle’) and panicle hydrangeas (such as H. paniculata ‘Grandiflora’ aka peegee hydrangeas). Prune these shrubs to the ground in the fall, late winter, or very early spring, and they will bounce back by spring.

Propagating Hydrangea

Since most hydrangeas are cultivars and hybrids, it is rare to get seeds for propagation. It’s more common to take stem cuttings or root a branch into the ground without cutting the shrub as a way to fill in gaps with a dense stand of shrubs.

Propagating by Cuttings

1. Select a light green, flowerless new growth stem in the early fall measuring 6 to 8 inches long.
2. Cut the stem below a leaf node (where a set of leaves will soon grow) with a sterile, sharp pruner.
3. Strip the bottom leaves, but keep the top set of leaves.
4. Carefully cut the remaining leaves in half horizontally (crosswise), not vertically.
5. Dip the bottom of the cutting in rooting hormone.
6. Place the end of the cutting into a small 8- to 10-inch pot filled with damp potting soil; one pot can hold several cuttings.
7. Cover the pot with a clear plastic bag, cut a couple of small slits at the top, and don’t let the bag touch any leaves.
8. Place the pot away from direct sunlight and keep the soil slightly damp.
9. Transplant the cutting in two to four weeks when the root system has begun to develop so it can strengthen over the winter.

Propagating by Rooting Branches Directly in the Soil

1. Bend a long stembranch so a large piece touches the soil.
2. Trim leaves from the part of the branch touching the soil.
3. Push the branch (or its tip) into the soil without breaking it.
4. Gently secure the branch in the soil with a brick or large rock (it won’t injure it).
5. Water the branch as you typically water the parent hydrangea.
6. Occasionally remove the weight and gently tug on the branch to see if it has rooted.
7. Once it has rooted, remove the weight and clip the branch from its parent plant so the new shrub will be self-sustaining.
8. If you want to transplant the newly rooted shrub, wait a couple of weeks after it’s clipped to dig it up so it is strong enough to be moved.

Potting and Repotting Hydrangea

Compact hydrangeas that grow under five feet tall make beautiful container plants. The pot needs at least four hours of morning sun daily and frequent watering since potted plants can dry out fast.

Start with a large pot with plenty of drainage holes that’s at least 16 to 24 inches in diameter to fit the plant’s root ball. Avoid terra-cotta and ceramic pots since they may crack over the winter. Fill it with potting soil and compost.

You may need to repot a growing hydrangea to a larger pot after three to five years when the roots reach all sides of the container.

Overwintering

Some types of hydrangeas, such as the bigleaf hydrangea, can be susceptible to winter bud damage. Protect hydrangea plants from the cold by wrapping them with burlap. Tie the branches together under the burlap for extra help to survive winter. Remove the burlap when the buds swell.

Outdoor potted hydrangeas can be overwintered much the same way, insulating them in burlap or bubble wrap for protection.

How to Get Hydrangeas to Bloom

How Long Does Hydrangea Bloom?

Hydrangeas can begin to bloom in July and continue into the fall. Some blooms may begin to appear as early as June.

A hydrangea from a florist won’t survive long. These gift hydrangeas are forced to bloom one time only and won’t do so again regardless of where you plant them.

What Do Hydrangea Flowers Look and Smell Like?

Some hydrangeas have large, round flower heads or cone-shaped panicles, while others have smaller, flatter, and more delicate flowers. Certain types of hydrangeas have a sweet scent while others do not.

How to Encourage More Blooms

To bloom, hydrangeas need plenty of sun, deep watering in the summer a few times a week, and minimal fertilizer formulated for acid-loving plants. Your hydrangeas may not bloom, because they’re in extreme sun, shade, or experiencing drought.

Caring for Hydrangea After It Blooms

Leave the flowers on the bush to dry out for winter interest. Deadheading the bush after it blooms will not hurt the plant. However, stop deadheading in the late fall to preserve buds that may form on old wood.

Common Pests & Plant Diseases

Hydrangeas can be affected by common pests, such as aphids, black vine weevil, the four-lined plant bug, Japanese beetles, and spider mites. Rose chafer pests can injure the plant by eating and leaving skeletonized leaves behind.

Hand-pick pests off plants and put them in pails of soapy water. Avoid using chemical insecticides or less harsh insecticidal soaps during the bloom period.

Hydrangeas are susceptible to diseases including botrytis blight, powdery mildew, and other viruses such as yellow or brown leaf spotting. Fungicides can help but likely need reapplication.

Common Problems With Hydrangea

Here are the most common problems that can occur with hydrangeas.

No Blooms

Hydrangeas may not bloom every season. They might have been pruned at the wrong time, the buds were damaged during unexpected cold snaps, or they may be overfertilized, underwatered, or affected by high heat.

Drooping Leaves

Drooping hydrangea leaves do not always mean the plant needs water. Hydrangeas protect themselves in hot weather by curling their leaves downward and appearing wilted. Look at the plant at dusk to see if it has recovered in the cooler temperatures. If not, it may need water.

Yellowing Leaves

Yellowing leaves may mean the plant has been overwatered, underwatered, or overfertilized. Try saving the shrub by saturating the roots if it’s too dry or overfertilized. Otherwise, try drying out the soil of an overwatered shrub.

Brown Leaves, Edges, or Tips

The plant’s roots may have burned from over-fertilization or if too much aluminum sulfate was added to the soil to change the color of the blooms.

Flush the soil with water to remove the excess salts or fertilizers. Then, let the soil surface dry for a day or two before watering again, and abstain from fertilizing until the plant is healthy again.

Color Loss

Hydrangea flowers may lose their color from too little water or too much hot sun in the afternoon. Or, the plant may be in transplant shock.