How to Grow Hydrangeas

Growing Hydrangeas

If a hydrangea doesn’t bloom, chances are it isn’t planted in the right spot. While some varieties tolerate more or less sunshine than others, in general hydrangeas do well with:

• • Light: Full morning sun, with some light afternoon shade.

• • Soil: Rich, crumbly, well-draining soil with plenty of organic matter.

• Water: They don’t have the word “Hydra” in their names for nothing! Choose a location with plenty of water and good drainage. Hydrangeas are thirsty plants, but they don’t like to sit in water.

Oakleaf hydrangea exhibit dramatic red foliage in the fall.

Planting Hydrangeas

When planting or propagating hydrangeas, keep in mind that:

• • Early summer is a great time to plant hydrangeas, but they are more readily available when blooming. Plant anytime throughout the growing season, although they will need TLC in hot weather.

• • Use lots of organic matter in the planting hole, especially if you have clay soil.

• • Make sure your hydrangea is planted at the same depth it was in the pot.

• • Hydrangeas can be propagated using softwood cuttings on an existing plant. Choose a nonblooming, new, soft green stem, and take a 6”- 8” cutting with several pairs of leaves. Remove the bottom leaves, dip in rooting hormone, and plant in light compost. Create a mini-greenhouse using glass jars or plastic. Place in a bright, shady spot, and keep moist until rooted. Transplant carefully into light, rich soil.

• Hydrangeas can also be propagated by burying a live branch in a technique known as ground layering.

Hydrangeas need rich soil and plenty of water

Caring for Hydrangeas

To keep your hydrangeas healthy, remember to:

• • Fertilize 2-3 times throughout the growing season with a balanced, slow-release organic fertilizer.

• • Keep hydrangeas mulched to hold in moisture. Organic mulches will also break down to enrich the soil.

• • Hydrangeas become visibly wilted if allowed to dry out. They need at least an inch of water per week during the growing season, and possibly more in hot, dry weather.

• • Deadheading promotes more blooms, although some gardeners like to leave the dried blossoms on the stalks during the winter.

• New growth can be cold-sensitive. Protect your hydrangeas from late-spring freezes, and don’t fertilize or prune in the fall.

Hydrangea blooms come in a wide variety of colors.

Pruning Hydrangeas

Pruning techniques for hydrangeas vary depending on the variety:

• • Bigleaf (H. macrophylla) and oakleaf (H. quercifolia) hydrangeas bloom on buds that emerge from old wood.
    In spring, only remove stalks you’re certain are dead. Heavier spring pruning will result in lots of new stems that won’t bloom until next year.
    After they bloom in summer, you can prune lightly for shape, and also thin the stalks – if desired – to encourage fewer, but larger, blooms.

• Panicle (H. paniculata) and smooth (H. arborescens) hydrangeas bloom on new growth, so they can be pruned in early spring to encourage a flush of new stems for summer blossoms.
  Some gardeners prune smooth hydrangea to the ground in the late fall and treat them as a perennial.

Bloom color varies even within the same plant.

Changing the Color of Hydrangea Blooms

The color of pink and blue hydrangeas depends on the amount of aluminum within the plant, which is controlled by soil pH. Acid soil (plus aluminum) makes the flowers blue, while alkaline soil turns them pink.

Gardeners love to manipulate this by adding supplements to achieve a desired flower color. Each variety reacts differently to color manipulation, and white varieties usually won’t change color at all.

Drying Hydrangea Blooms

Hydrangea blossoms make lovely dried flowers. Leave them on the plant until they are papery-feeling and partially dry.

Carefully cut the stems and hang the flowers upside down, or stand them in a jar, until completely dried.

Further Information

• When to Prune Hydrangeas (article)
• Hydrangea Questions and Answers (U.S. National Arboretum)
• Hydrangeas! Hydrangeas! (website on Hydrangeas)
• Hydrangea Propagation by Ground Layering (video)