How to identify old vs. new wood hydrangeas?
Written by
Paul Reynolds
Reviewed by
Prof. Charles Hartman, Ph.D.The first clue in distinguishing between old and new wood hydrangeas is when to check for buds. Old wood types, like bigleaf and oakleaf hydrangeas, form next season's buds on last season's stems in late summer. New wood types, such as panicle hydrangeas, create their buds on this year's growth every spring. It is best to check the stems for buds in August, and old wood types should show plump buds and new wood types will be undifferentiated and smooth.
Old Wood Hydrangeas
- Bud formation begins in late summer
- Stems have visible nodes from prior growth
- Bloom failure if pruned after August
New Wood Hydrangeas
- No buds until spring growth emerges
- Flexible green stems in early season
- Tolerate late winter/early spring pruning
A while back, I assisted a gardener with an unknown variety of hydrangea using dormant buds to determine its identity. When I scraped a stem in March, I found green tissue, which indicates the hydrangea is an older "old wood" type variety. Newer types flower on "new wood," so you should look for fast stem elongation in the spring or simply no pre-formed buds.
Read the full article: When to Prune Hydrangeas: A Step-by-Step Guide
