How & When to Prune Hydrangea Petiolaris

by Patricia H. Reed

Patience is definitely a virtue when you're growing climbing hydrangea (Hydrangea anomala petiolaris). This deciduous, woody vine can reach up to 50 feet long and produce huge white multi-flower blooms in U.S. Department of Agriculture plant hardiness zones 4 through 8, but it takes its sweet time getting started. Slow growth and no blooms for the plant's first five years are not uncommon, so leave your pruning tools in the shed until your hydrangea vine is fully established and decides it's time to start climbing.

1 Spray the blades of your bypass pruners with household antiseptic cleaner, and wipe them down with a paper towel to avoid passing on any plant disease or fungus that could remain on the blades from other plants.

2 Assess your climbing hydrangea in midsummer after the vine has bloomed -- if it has begun to bloom. When your climbing hydrangea has started to send up vines longer than you'd like but has never bloomed, check that no flower buds are forming on the tips of stems or wait until late summer, when the plant's potential blooming period has passed.

3 Clip off any faded flowers with bypass pruners at the next leaf down the stem. If you like the look of the dried flower heads, you can leave them on the plant until spring and remove them just above the new buds.

4 Remove any stem that is dead or broken at its base with bypass pruners.

5 Follow any stem that is either arching away from the wall or other support, or is shooting out from the main body of the vine in a way you don't like back to where it joins the main stem or to 1/4 inch past a bud that would restart growth in the direction you prefer. Make your cuts at a 45-degree angle.

6 Pull the stems away from the wall if they don't fall away on their own, and pull as much of the aerial root off the support as possible.

7 Reduce old, overgrown climbing hydrangeas in the spring, cutting the oldest or most out-of-control stems back to the main trunk -- you may sacrifice some flowers, but will get your house or wall back. Remove no more than one-third of the plant in a single season or what remains may not bloom well for several years.

Items you will need

  • Bypass pruners
  • Household antiseptic cleaner
  • Paper towels
  • Ladder, as needed

Tips

  • No pruning is necessary unless the plant is growing too large for its space.
  • Long-handled loppers with extendable handles can help your remove stems up high while keeping your feet on the ground, though cuts may not be as precise.

Warnings

  • When using a ladder, make sure its feet are firmly planted and you can comfortably trim the vine without overreaching or climbing beyond the third step from the top. Call a professional to prune a climbing hydrangea that has grown any taller or is within 10 feet of a power line.
  • A hard-bristled scrub brush or a paint scraper may be necessary to remove the residue from established aerial roots.
  • Climbing hydrangea can cause stomach distress if eaten by children or pets.