How to Plant, Grow, and Care for Hydrangea Trees

Some shrubs stand out because of their natural qualities, like the impressive bigleaf hydrangeas and their mophead bloom clusters. Others, like hydrangea trees, are impressive because they look like nothing else you’ve ever seen.

Hydrangea trees are the same species as panicle hydrangeas. The two are simply different forms of the same plant. Multi-stem shrubs grow naturally, while the tree forms require specific pruning cuts to form their shape.

Because these trees have a single trunk, hydrangea tree care is slightly different from regular panicle hydrangea shrubs. Give them good soil, a sunny exposure, and proper pruning, and they’ll reward you with giant blooms from summer through fall.

What Is It?

This woody perennial is a form of Hydrangea paniculata that growers shape into a tree. It varies in bloom color and mature height depending on the specific variety. Some stay compact and dense, while others are wide-reaching and long-stemmed. 

Native Area

H. paniculata, or panicle hydrangea, is native to the countries of East Asia. It grows in China, Japan, Sakhalin Island, and Taiwan. Nowadays, it grows outside of its native range in Korea and the eastern portions of the U.S. 

The panicle hydrangea is popular worldwide in home landscapes, and it’s common wherever formal gardens exist. You may have seen it already without realizing it’s the same species as hydrangea trees.

Characteristics

Hydrangea trees sprout oval, pointed leaves from woody stems. The species has green flower buds that emerge and open into white blossoms. The petals shift to pink as they fade, creating an illustrious display of color in the home garden. 

The blossom clusters have a few showy, sterile flowers that adorn the outer portions. The inner, inconspicuous flowers are not sterile, and they are the ones that attract pollinators. New cultivars have clusters that are all sterile, and they form giant panicles that outmatch those of bigleaf hydrangeas. 

Cultivars now have flowers in shades of white, pink, green, and red. Find your favorite cultivar, or opt for the strong and vigorous species type. Depending on the variety, hydrangea trees can range from 10 to 25 feet tall.

Planting

To form a tree, you must prune this shrub in a specific way to influence its growth. Find a small panicle hydrangea shrub and prune it, or locate a pre-pruned tree that’s ready to transplant.

Tree hydrangeas cost more than the shrubby ones, and shaping a shrub yourself takes more time. The best option for you depends on how much time and money you have to spend.

Transplanting

The easiest way to get this tree in your yard is to find one at a nursery. Look to local garden centers and plant nurseries, and ask for a hydrangea tree, or for a hydrangea on a standard trunk. As these unique specimens grow in popularity, they’re becoming more and more common wherever shrubs are available. 

Start the transplanting process by preparing a hole for planting. Dig the hole as deep and twice as wide as the plant’s rootball, then set it inside. Bury the roots with the soil you dug out, ensuring that the soil reaches up to the root flare where the trunk begins and the roots end. 

Cover the site with a thick layer of compost to insulate and feed the newly planted shrub, and water the area well. Ensure it stays moist while the woody perennial adapts to its new home. 

When transplanting, stake the tree if it’s wobbly or weak. The trunk will thicken over time to support the weight, but it’ll be weak immediately after planting. The extra support will help it while it establishes itself. Then, you may remove the stake after six months to a year. 

Growing from Seed

Starting hydrangeas from seeds requires patience and diligence. You’ll need to nurture seedlings for a few years before they’re ready for pruning and shaping. If you’re up to the challenge, start the process by sourcing seeds. 

Gather seeds from local hydrangeas or purchase them online. They’re tiny, so take extra care when collecting and handling them. Surface sow them in trays with potting soil, and keep them under a well-lit location like a sunny windowsill.

Keep the seeds moist by misting the soil frequently. Ensure it doesn’t dry out, and you’ll see seeds germinate within two to four weeks. Let them mature, then transplant them into larger pots once they have two true leaves. 

Training

Instead of buying an expensive ready-made tree, you may shape a small shrub yourself to make it grow into a tree. Start with a panicle hydrangea shrub from the nursery, or start seedlings from seeds and shape them as they mature. 

You may shape this species in late winter, early spring, or fall. Look at the shrub’s overall structure. Is there a single stem growing upright near the inside of the shrub? Choose one as the trunk, then remove all the other low-growing branches. 

On the trunk, prune each of the upper stems back a few inches. This will encourage more shoots to form, and it’ll help the trunk thicken to support the heavy top growth. Remove any suckers as they grow to keep the single trunk as the main stem.

If you have a giant shrub you want to transition to a tree, you’ll need to spread out your pruning over a few seasons. You don’t want to shock the shrub! Remove up to half of the stems this year, then wait until next year to remove the other half, leaving one stem to remain. 

How to Grow

Hydrangea tree care is largely the same as panicle hydrangea shrubs. Give it plenty of light, water, and air to encourage it to thrive. It’ll grow well in home gardens from USDA hardiness zones 3 through 8. 

Light

Hydrangea trees grow best in gardens with full sun or partial shade. They need at least three to six hours of daily direct sunlight. The less sun they get, the fewer blooms they’ll produce.

In gardens with hot summers, consider planting your hydrangea tree in an area with protection from afternoon sun during the hottest hours. In regions with cool summers, give your hydrangea as much direct sunlight as possible. 

Water

Regular water is key to hydrangea tree care. It needs consistent moisture during the growing season to stay turgid and vigorous. You’ll notice your tree growing thirsty when its leaves turn limp and point downward. 

Potted specimens need more water than those in the ground. Check the soil by sticking your finger in the pot. If it feels dry underneath the surface, then it’s time to water the pot. 

Soil

These trees prefer well-drained loamy soil. If the site has dense clay or dry sand, amend it with compost. Compost will influence the ground over time, creating nutrient-rich humus that’s porous and absorbent. 

Amend the site by adding a layer of compost two to three inches thick. Rake it in to incorporate it into the topsoil, then water it well. The goal is to have compost always covering the ground, as bare soil invites weeds, diseases, and pests. 

Fertilizing

Continuous feedings of compost are sufficient for hydrangea tree care. If you’re using a low-nutrient mulch, like straw or leaves, you may want to consider adding an annual dose of organic fertilizer.

Annual helpings of fertilizer give your tree the nutrients it needs to grow spectacular flower panicles. Use a liquid or powder type, and water it into the soil according to the dosing instructions on its label. 

Maintenance

Pruning and protecting the trees from frost are the two most important maintenance tasks in hydrangea tree care. Proper pruning creates a strong tree with a thick trunk, and frost protection keeps the tree safe through the winter.

To keep your tree manageable, you may want to consider pruning the stems back to 10 feet tall every year. This will keep them within reach of your loppers. Do so from fall through early spring, but not during early summer, as pruning in early summer will lop off the budding blooms. 

If you’d like fewer, bigger bloom panicles, thin the stems so that five or ten remain. The fewer stems there are, the bigger the flower heads will be. 

To protect the deciduous tree from frost, mulch the soil during the fall with a thick layer. Use compost, leaf mold, fallen leaves, straw, or whatever else you can source in your backyard.

Propagation

Propagate your favorite cultivars with cuttings or seeds. Cuttings create clones of the original tree, while seeds have the potential to sprout into new, quirky varieties. Use cuttings to make replicas, and seeds to find new hydrangeas. 

Take Cuttings

Take softwood cuttings during the growing season. Snip a portion of the stem that’s four to six inches long with leaves on its end. Strip each stem of the lower leaves, but leave the ones on top to remain. 

Stick each cutting into trays or pots with potting soil, and keep the soil moist but not soggy. Place the cuttings under bright, indirect sunlight outdoors or grow lights indoors. You may also use a sunny windowsill indoors. 

The cuttings should root within a month or longer, depending on the growing site’s conditions. Aim to keep them as moist as possible to encourage root growth. If they’re struggling, consider adding a humidity dome to trap moisture for the leaves. 

Save Seeds

It’s only possible to save seeds from cultivars that have fertile flowers. The showiest trees with giant blooms often lack the flowers necessary for seeds to form. 

If you do find seeds, collect them in the fall when they’re mature. Snip the spent bloom head off and place it in a brown paper bag. The seeds will fall to the bottom of the bag when they’re ripe. 

Collect the seeds and place them in a container, such as a glass jar or a plastic bag. Store the containers in a cool, dark, and dry place. Use the refrigerator, or store them in a closet or pantry.

Popular Varieties

There used to be one main variety, ‘Grandiflora,’ for the longest time. Nowadays, cultivars pop up annually! Try the classic ‘Grandiflora,’ or go for the new types ‘Limelight’ and ‘Burgundy Lace.’

Grandiflora

This variety is famous for its giant flower clusters that reach up to a foot and a half long. They’re impressive, and they stand out in the landscape. 

The downside to ‘Grandiflora’ is its giant size. It may reach 20 feet tall and wide to make a large impact in the garden. Use this to your advantage, or prune the stems annually to keep them within arm’s reach. 

Limelight

‘Limelight’ flower clusters reach a foot long. Though not quite as large as the previous variety, they sprout from stems that max out at eight feet long. This means ‘Limelight’ trees will stay compact and dense throughout their lifetime.

It also means they’re easy to care for! Give them mulch before winter, and prune them as necessary to shape and trim them. Deadhead the blooms in the fall if you prefer a neat appearance. 

Burgundy Lace

‘Burgundy Lace’ stands out from the previous two with its pink flower clusters. The clusters are loose in appearance, as they contain both fertile and sterile, showy blooms. 

The clusters emerge white, and they turn to pink and burgundy as the seasons progress. Like ‘Limelight,’ this cultivar stays around eight feet tall when mature, making it easy to care for in the home garden. 

Common Problems

You shouldn’t encounter many issues with the right hydrangea tree care. Watch for aphids and mites during the growing season, and look out for a few diseases in sites with poor soil or improper growing conditions. Keep your hydrangeas healthy to help them resist most pests and diseases. 

Pests

Aphids and mites attack the leafy foliage that sprouts during the growing season. They need warm temperatures to survive, and winter frosts suppress their populations. 

If aphids or mites expand throughout the hydrangea tree, hose them off with a strong blast of water. Spray the leaves daily until the pesky critters leave the site. 

Diseases

Watch for bud and leaf blights, conditions that cause the foliage and buds to wither and decay. They’re common in moist, crowded environments. Lower the humidity levels and space the trees apart to prevent the blights from thriving in the soil.