Growing Tips: Hydrangeas, Pruning for Blooms
Six hydrangea types most commonly grace our landscape. In eastern and southeastern Massachusetts, bigleaf hydrangeas (Hydrangea macrophylla), and their many cultivars, are especially popular.
Most Hydrangeas Thrive Given:
- Full sun or partial shade, depending on the cultivar. Avoid hot, dry, sites
- Moist, well‐drained soils enriched with organic matter. Mulch with 2‐3 inches of bark mulch or other organic mulch to conserve moisture.
When is the best time to prune hydrangeas?
It depends on the type and when they produce flower buds. See table below for guidance.
Why aren't they blooming?
There are three possibilities:
- too much shade
- improper pruning
- winter damage to stems, or frost damage to flower buds – especially likely with bigleaf hydrangea (Hydrangea macrophylla) and mountain hydrangea (Hydrangea serrata)
Nifty Note:
Look for newer cultivars of bigleaf hydrangea that bloom on last summer’s (old wood) and current spring (new wood) growth. Cultivars such as 'Endless Summer'®, 'Blushing Bride'™ and 'Twist‐n‐shout' ™, 'Red Sensation', 'Double Pink' will bloom again on the current year’s growth if you remove faded blooms regularly.
| Hydrangea Type | Best Time to Prune | Zone | Notes |
|---|---|---|---|
| bigleaf hydrangea, French hydrangea (H. macrophylla) |
right after bloom, in summer; prune winterdamaged stems in late spring, after leaf‐out | 6‐ 9 | Blooms in spring, early summer; then flower buds produced on summer growth. Native to Asia |
| mountain hydrangea (H. macrophylla var. serrata) |
(same as above) | 5-9 | (same as above) |
| smooth hydrangea (H. arborescens) |
late winter, early spring, before leaf‐out; can cut back to 6” – 12” above ground. | 4 ‐ 9 | Flower buds produced on spring/early summer growth, then blooms mid‐summer. Native to Eastern United States |
| panicle hydrangea (H. paniculata) |
late winter, early spring, before leaf‐out | 4‐ 7 | Flower buds produced on spring growth; then blooms mid‐summer. Native to Asia |
| oakleaf hydrangea (H. quercifolia) |
right after bloom, in summer; prune winterdamaged stems in late spring, after leaf‐out | 5 ‐ 6 | Blooms early summer; then flower buds produced on summer growth. Native to SE United States |
| climbing hydrangea (H. anomala subsp. petiolaris) |
Usually not necessary, except to remove damaged wood | 5-8 | Native to Asia |
Resources
https://www.mass.gov/orgs/massachusetts-department-of-agricultural-resou...
www.massflowergrowers.com
http://ag.umass.edu/resources/home-lawn-garden
