Growing Hydrangea Tree Form

Pronunciation: hye-dran'jee-uh  

Planting: When you're ready to plant your bareroot tree, fill a 5-gallon bucket, or equivalent container, with water to soak the roots of your plants for an hour or so before they go in the ground or into a container. Unwrap your plant, remove the packing material, and place its roots in the water.

If planting in the ground, dig a hole wide and deep enough to accommodate the roots. Remove your tree from the water and plant the crown at the depth indicated on the plant label, arranging the roots evenly inside the hole. Holding the crown of the plant, push the soil into the hole, working soil around the roots. Firm the soil around the crown, pressing down with both hands. Water thoroughly to settle the soil.

If planting in a container, choose one that is 10-12" in diameter and use good-quality potting soil. Place the container outdoors for the growing season. Plants in containers dry out more quickly than plants in the ground, so it’s important to water your plants regularly.

To keep your tree standing, put it out of reach of strong winds and support it with a stake that has a diameter at least as large as the stem’s diameter and long enough that when pushed into the soil it reaches inside the head of the tree. Fasten the standard to the stake at several points with garden twine or green plastic tie tape looped in a figure eight around the stem and stake. Check the ties periodically during the growing season. Loosen them if they constrict the outward growth of the stem.

Pruning, Fertilizing, and Repotting: Maintain the shape of the head with selective pinching of the new shoots in early spring. Pinch each shoot between thumb and forefinger or cut with pruning shears. Do not shear the plant as though it were a hedge. Fertilize tree forms grown in pots as you would other pot-grown plants by using a balanced, time-release fertilizer.

If you find that your tree in a container starts to dry out quickly after watering, the plant probably needs a larger pot. Lift it from its current pot, make four deep vertical cuts in the root ball, and place it in a new pot that is 2" wider and taller than the old one, filling in around the root ball with fresh potting mix. Water thoroughly after repotting.

Wintering Over in Containers: In colder climates (Zones 4, 5, and 6), you can overwinter plants in their containers by storing them in a sheltered, unheated area, such as a garage or shed, where temperatures range between 25 and 40°F. Check the potting mix occasionally for moisture, and water as needed. In warmer climates where freeze-thaw cycles occur, store plants on a protected porch. Where freezing is not a concern, plants can remain outdoors in containers and enjoyed year round.