when to prune hydrangeas seattle

When to Prune Hydrangeas in Seattle: A Guide

Knowing when to prune hydrangeas in Seattle is crucial for healthy growth and abundant blooms. The timing depends on the type of hydrangea you have; some bloom on old wood (last year’s growth), while others bloom on new wood (this year’s growth).

Understanding the blooming habit of your specific hydrangea variety is the first step to successful pruning in the Pacific Northwest’s climate. Pruning at the wrong time can remove flower buds, resulting in fewer or no blooms the following season.

Understanding Hydrangea Types and Their Blooming Habits

Hydrangeas are broadly classified into types that bloom on either old wood or new wood. This distinction dictates the optimal pruning time.

Old Wood Bloomers

These hydrangeas, including Hydrangea macrophylla (bigleaf hydrangeas, including mopheads and lacecaps) and Hydrangea serrata (mountain hydrangeas), form their flower buds on the previous year’s growth. Pruning these types at the wrong time will remove the buds, resulting in few or no flowers the following year.

New Wood Bloomers

Hydrangeas that bloom on new wood, such as Hydrangea paniculata (panicle hydrangeas, like ‘Limelight’ and ‘Pinky Winky’) and Hydrangea arborescens (smooth hydrangeas, like ‘Annabelle’), produce flower buds on the current year’s growth. These can be pruned more freely without sacrificing blooms.

Optimal Pruning Times in Seattle

Seattle’s climate, with its mild winters and wet springs, influences the best pruning times for hydrangeas.

Pruning Old Wood Hydrangeas

For old wood bloomers, the ideal time to prune is immediately after they finish flowering, typically in late summer (July or August). This gives the plant ample time to develop new growth and set flower buds for the following year. Avoid pruning in the fall, winter, or early spring, as you risk removing the developing buds.

Deadheading (removing spent flower heads) can be done anytime to improve appearance, but avoid cutting back stems unless necessary to remove dead or crossing branches.

Pruning New Wood Hydrangeas

New wood bloomers can be pruned in late winter or early spring (February or March) before new growth emerges. You can prune them back fairly hard to encourage bushier growth and more abundant blooms. Hard pruning encourages larger flower heads, although some prefer to lightly prune to encourage stronger stems.

Deadheading is also beneficial for new wood bloomers and can be done throughout the growing season to encourage further flowering. More about Hydrangea plant.

Pruning Techniques

Regardless of the hydrangea type, always use clean, sharp pruning shears to make clean cuts, which helps prevent disease. Remove any dead, damaged, or crossing branches. For old wood bloomers, focus on removing only the oldest canes to encourage new growth. For new wood bloomers, cut back stems to about 12-18 inches above the ground to promote vigorous new growth.

Frequently Asked Questions

When is the best time to prune my Endless Summer hydrangea in Seattle?

Endless Summer hydrangeas bloom on both old and new wood, making pruning less critical. Lightly prune after the first flush of blooms to encourage more flowers. You can also remove dead or crossing branches anytime.

What happens if I prune my old wood hydrangea at the wrong time?

Pruning old wood hydrangeas in the fall, winter, or early spring will likely remove the flower buds, resulting in few or no blooms the following season.

How do I know if my hydrangea blooms on old wood or new wood?

Observe when your hydrangea blooms. If it blooms in early summer, it likely blooms on old wood. If it blooms later in the summer or fall, it likely blooms on new wood. Also, check the plant label or research the specific variety.

Can I prune my hydrangeas in the fall in Seattle?

It’s generally best to avoid pruning old wood hydrangeas in the fall. New wood hydrangeas can tolerate light pruning in late fall if needed, but early spring is preferable.

How much should I prune my hydrangeas?

For old wood bloomers, prune lightly, focusing on removing dead, damaged, or crossing branches. For new wood bloomers, you can prune more aggressively to encourage bushier growth and more flowers.

Summary

Successful hydrangea pruning in Seattle hinges on knowing your hydrangea type and pruning at the correct time. Old wood bloomers should be pruned immediately after flowering, while new wood bloomers can be pruned in late winter or early spring. Proper pruning techniques will ensure healthy growth and a profusion of blooms each year.