Gardening Plants & Flowers Shrubs

How to Grow and Care for Hydrangeas

closeup of a pink hydrangea

The Spruce / Claire Cohen Bates

Hydrangeas are one of the most popular ornamental garden plants because of their large flower heads that come in a wide array of colors. Hydrangeas are versatile shrubs that thrive in sandy coastal soils, shady woodland sites, and almost everything in between. Care for hydrangeas by giving them full sun in moderate climates and morning sun in hot areas, humus-rich soil when possible, and consistent moisture without waterlogging the plant. Hydrangeas are rapid growers, averaging 2 feet or more of growth per year. Be aware that the plant is toxic to animals.

Watch Now: 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 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 a hydrangea according to the hydrangea's species and the time of year when it sets buds.
blue hydrangeas

The Spruce / Claire Cohen Bates

bright blue hydrangeas

The Spruce / Claire Cohen Bates

oakleaf hydrangeas
The Spruce / Adrienne Legault

Light

Hydrangeas do well in the partial shade provided by tall deciduous trees, especially if they receive morning sun and the partial shade occurs in the heat of the afternoon. Too much shade can reduce flower output. They will also thrive in full sun but might need extra water on hot summer days.

Soil

In general, hydrangeas can tolerate a wide range of soil types but they grow best in fertile, humus-rich soil. A notable characteristic of Hydrangea macrophylla is that you can control bloom color by adjusting the soil pH. Acidic soil with a pH of 6.0 or lower produces blue flowers and neutral to alkaline soil with a pH of 7.0 or higher produces pink blooms.

Water

Hydrangeas need consistent moisture throughout the growing season. Give your hydrangeas a deep drink of water one to two times every week. If your area has had significant rainfall, you can cut back on supplemental watering. Water deeply each time until the ground feels saturated but is not waterlogged. A light watering every day is not sufficient because the water will not reach the root system to hydrate the plant.

During particularly hot weather, increase the amount of water you give your plants so the soil remains damp, but make sure they're not sitting in soggy soil. To know if you need to water your hydrangea, stick your finger down about 4 inches into the ground and if it feels dry to your fingertip, it's time to water.

In extremely hot weather, hydrangeas might curl their leaves and appear wilted. This is a built-in protection and does not necessarily mean that the plant needs water. If you observe this behavior, take another look at the plant at dusk to see if it has recovered once temperatures have cooled down.

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.

Because hydrangeas prefer to grow in partial shade, they usually do best when planted in a north- or east-facing site, where winter temperatures remain somewhat constant. Avoid planting on the south and west side of your property where the warmth of winter sun could cause buds to swell prematurely and become vulnerable to cold snaps.

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

Fertilizer

If your soil is rich in nutrients, you likely won't have to fertilize your hydrangeas. In fact, if hydrangeas are given too much high-nitrogen fertilizer, the foliage will be full and lush but with fewer blooms. If the soil is not fertile, in the spring spread of layer of organically rich compost around the plants or apply a fertilizer suitable for flowering shrubs.

Types of Hydrangea

Of the many species of hydrangea, the following are the most commonly used as ornamental shrubs. Some of these hydrangea species bloom on new growth (the current year's new stems), while others bloom on old growth (last year's stems).

  • Hydrangea macrophylla: Also known as bigleaf, mop head, or lacecap hydrangea, this species grows 6 to 10 feet tall and wide and has 6-inch leaves. Bloom color is affected by soil pH; acidic soil produces blue blooms and alkaline soil produces pink blooms. Buds for the following year are set in midsummer through fall.
  • Hydrangea 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.
  • Hydrangea quercifolia: Commonly called oakleaf hydrangea, this plant reaches around 7 feet tall and wide with white to purplish-pink flowers. Its leaves look similar to the oak tree, thus its common name. Buds are set in midsummer through fall.
  • Hydrangea paniculata: Commonly called panicle hydrangea, the blooms on this species are cone-shaped rather than round or flat. For many cultivars, the flowers start out white and gradually change to light pink and then to a darker pink as they mature. This plant grows quite large if left unpruned, up to 15 to 20 feet tall and wide. This species blooms on new stem growth.

Pruning


The right time to prune a hydrangea varies according to the hydrangea species and the time of year when buds are set. Thus, it is important to know the type of hydrangea you are growing to know when to prune it.

Propagating Hydrangea

Since most hydrangeas are cultivars and hybrids, it is rare to get seeds for propagation. However, there are two common ways to propagate the plant. Taking stem cuttings at the right time may result in stronger, more resilient roots that nearly guarantee success when transplanting hydrangeas into the ground. The second method is to root the hydrangeas right into the ground without having to cut into the shrub until the last step. This is the preferred method if you want to fill gaps between shrubs in your garden or you want a more dense stand of shrubs.

Propagating by cuttings

  1. In the very early fall, select a new growth stem at least 6 to 8 inches long that does not have a flower. New growth will be lighter green than old growth.
  2. With a sterile, sharp pruner, cut the stem below a leaf node (a node signifies where a set of leaves are set to grow). Keep a set of leaves on the stem in addition to a node.
  3. Strip the bottom leaves, but keep the top set of leaves. Carefully cut the remaining leaves in half horizontally (crosswise), not vertically.
  4. Dip the bottom of the cutting in rooting hormone.
  5. 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.)
  6. Make a mini-greenhouse by covering the pot with a clear plastic bag and closing it at the bottom of the pot. Cut a couple of small slivers on top of the bag so the cutting can breathe. Do not let the bag touch any of the leaves.
  7. Put the pot in a spot that is away from any direct sunlight and keep the soil slightly damp.
  8. In two to four weeks, a root system should begin to develop. You can transplant the cutting so that it can have the winter to establish a strong root system.

Propagating by rooting branches directly in the soil

  1. Bend down a long stem/branch so that a large piece of it touches the soil.
  2. Trim leaves from the part of the branch that is touching the soil.
  3. Push the branch down into the soil as best as you can without breaking the branch. You could also push the tip of the branch into the soil.
  4. Secure the branch by weighing it down with a brick or large rock. You won't injure the branch.
  5. Water the branch just as you typically water the parent hydrangea.
  6. Occasionally remove the weight and gently tug on the branch to see if it has rooted. Once rooted, you no longer need to weigh it down.
  7. Once it has rooted, you will need to clip the branch from its parent plant so the new shrub will be self-sustaining.
  8. If you do want to dig up the newly rooted shrub to move it, wait a couple of more weeks after you've clipped it so it can be strong enough for transplanting.

Potting and Repotting Hydrangea

Compact hydrangeas that grow under 5 feet tall make beautiful container plants. Make sure the pot gets at least four hours of sun per day, preferably morning sun, and water frequently since potted plants can dry out fast. Start with a large pot (with large drainage holes) that's at least 16 to 24 inches in diameter to adequately fit the root ball of the plant. 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.

Avoid terra-cotta and ceramic pots since they may crack over the winter. Overwinter the pot by keeping it outdoors, but protecting it from harsh winds and also insulating the pot with layers of burlap or bubble wrap.

Overwintering

Some types of hydrangeas, such as the bigleaf hydrangea, can be susceptible to winter bud damage. If you live in a very cold area with harsh winters, protect your hydrangea plants from cold winds by wrapping them with burlap or putting up burlap screening. You can also tie the branches together along with the burlap to give them extra help to survive winter. Remove the burlap when the buds begin to swell.

Common Pests & Plant Diseases

The usual types of garden pests can affect hydrangeas, including 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. Chemical insecticides or less harsh insecticidal soaps may help eliminate most of these insects, but avoid using them during the bloom period. Instead, hand-pick these pests into pails of soapy water.

Hydrangeas are susceptible to diseases including botrytis blight, powdery mildew, and other viruses such as yellow or brown leaf spotting. Fungicides can help with most problems but destroy plants infected with viral spotting.

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.

It's also important to know that if you received a gift hydrangea that did not come from a garden center but instead came from a florist, it is unlikely to survive for 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 flower heads, along with varying foliage shapes depending on the species. Certain types of hydrangeas have a scent while others do not. Some that have a sweet fragrance include panicle hydrangeas (such as the peegee hydrangea) and climbing hydrangea (Hydrangea anomola subsp. petioloaris).

How to Encourage More Blooms

There are many reasons your hydrangeas may not be blooming, including extreme sun, shade, and drought, all of which can greatly reduce the number of blooms. To help increase blooms, water the plant deeply a few times a week, especially in the summer, but don't keep the soil soggy. Do not fertilize with a high-nitrogen food, either, or else the foliage will become lush at the expense of flower production. Instead, use food for acid-loving plants.

Caring for Hydrangea After It Blooms

You can leave the flowers on the bush to dry out for winter interest. Or you can deadhead them after blooming. Deadheading will not hurt the plant. However, stop deadheading in the late fall to preserve any buds that may form on old wood.

Common Problems With Hydrangea

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

No Blooms

Hydrangeas may not bloom every season. The reason could be pruning at the wrong time of year, damage to buds during unexpected spring or winter cold snaps, or at some point you may have overfertilized the plant.

Drooping Leaves

Hydrangea leaves can droop due to lack of water. This happens during bloom time or very hot, dry weather, so keep hydrangeas consistently moist.

However, drooping leaves might not always be a sign that a hydrangea needs water. These plants have a built-in protection mechanism where they will curl their leaves downward in extremely hot weather and appear to be wilted. When daytime temperatures are around 90 degrees Fahrenheit or higher and you observe this behavior, take another look at the plant at dusk to see if it has recovered once temperatures have cooled down. If the plant is still wilted as temperatures cool, that could be a sign of dry soil that requires deep watering.

Yellowing Leaves

Yellowing leaves can indicate that a plant has been overwatered, underwatered, or overfertilized. It might be possible to save the shrub by saturating the roots if the problem is that it's too dry or overfertilized. Otherwise, you may need to dry out the roots of an overwatered shrub in the hope that it saves the plant.

Brown Leaf Tips or Edges or Tips

This problem can occur if the roots have been burned by over-fertilization. Brown edges or tips can also occur if too much aluminum sulfate was added to the soil to change the color of the blooms. If this occurred, 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 once again.

FAQ
  • Can hydrangeas grow indoors?

    Yes and no. Oftentimes greenhouse-grown potted hydrangeas are given as springtime gifts for indoor enjoyment, but it can be tricky to maintain them. For example, an indoor hydrangea plant can be finicky; It will be happiest in a room between 50 and 60 degrees Fahrenheit, but unhappy in warmer spaces. It might be best to plant your potted hydrangea outdoors in your garden for best results.

  • How can I change the color of my hydrangeas?

    You can change the color of some hydrangea flowers by tinkering with the soil pH. Change blue flowers to pink flowers by decreasing the acidity of your soil. Do this by adding hydrated lime to the soil in the spring. To change pink flowers to blue flowers, increase the acidity of the soil. Do this by adding aluminum sulfate to your soil in the spring. Color change does not happen immediately—it can take a while for the plant to acclimate itself to adjustments to soil pH.

  • How can I tell if my hydrangea blooms on new wood or old wood?

    These terms can be confusing, which often leads to pruning off the woody stems that could hold the buds for next season's blooms. Make a note of the type of hydrangea you have, when it blooms, and the best pruning practices for the plant. If your hydrangea blooms in the early summer, you likely have a plant that flowers on old wood (previous year's stems). If your hydrangea blooms mid to late summer, you probably have a plant that flowers on new wood (the current year's stems).

  • Can I train a hydrangea shrub to grow into a flowering tree?

    Yes, you can train a hydrangea shrub into a small flowering tree with a single trunk, but be patient because the process can take a few seasons to complete. Many gardeners prune limelight hydrangeas into trees because they grow to just the right height for an ornamental tree. In addition to limelight, there are other types of hydrangeas (Hydrangea paniculata) that are easy to train into ornamental trees.

Watch Now: How to Prune Hydrangeas

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  2. Hydrangea. ASPCA.

  3. Hydrangeas in the Garden. Rutgers University New Jersey Agricultural Experiment Station.

  4. Are there fragrant hydrangeas? New York Botanical Garden.