Climbing hydrangeas (Hydrangea petiolaris) are beautiful, versatile plants known for their ability to cover walls and fences, reaching heights of up to 15 meters and spreading up to 5 meters wide. Over time, however, these vines may lose their shape, and pruning becomes necessary to encourage healthy growth and abundant blooms. In this guide, we’ll walk you through the best practices for pruning climbing hydrangeas, ensuring they remain strong and beautiful year after year.
Why Should You Prune Climbing Hydrangeas?
Climbing hydrangeas grow slowly in their early years, often not blooming until they are five to eight years old. During this time, pruning is not typically needed. However, once the plant matures and starts climbing quickly—sometimes growing up to a meter per year—it can become unruly or put excessive weight on one side. Regular pruning helps maintain its shape, remove weak or overcrowded growth, and improve air circulation, which reduces the risk of fungal diseases.
Removing dead wood also prevents fungi from using the old branches as a place to overwinter. Furthermore, pruning helps keep the plant from toppling over due to heavy growth or broken branches.
Pruning for More Blooms
If your climbing hydrangea’s blooms start to decline over the years, it may be time for a rejuvenation cut. This involves cutting back the main stems, forcing the plant to produce new growth and activate dormant buds. Dormant buds are those that were formed in previous years and will only start developing when the older stems are pruned back. This type of pruning promotes a fresh burst of growth and a more vigorous flowering cycle.
Tip: Be careful not to prune young climbing hydrangeas in late spring, especially in frost-prone areas, as the cuts might be damaged by late frosts.
When to Prune Climbing Hydrangeas
Climbing hydrangeas bloom on last year’s growth, meaning they form their flower buds in the autumn after they have finished flowering. Therefore, pruning should be done after the flowering season to avoid cutting off next year’s blooms.
You can also perform a « maintenance prune » in early spring, usually between February and March. This involves removing dead wood, dry flowers, and any weak or unruly branches that may be sapping the plant’s energy. In addition, every four to five years, you may need to do a more drastic rejuvenation cut if the plant is overgrown or has fewer flowers.
Step-by-Step Guide: How Much to Prune
- After Flowering: Use a sharp garden shears to cut off the old flower heads and trim the growth directly above the first set of buds.
- Spring Maintenance: In early spring, remove dead wood or unwanted branches that are crowding the plant. For the rejuvenation prune, cut the main stems back to around 2.5 meters, depending on the plant’s size. For thicker branches, use a pruning saw or lopper.
- Rejuvenation Prune: If needed, perform this radical pruning every few years to encourage the plant to regrow vigorously. Be sure to only cut back a few stems at a time to avoid cutting off too many flowering buds at once.
Tip: Pay attention to the direction of growth, especially if your hydrangea is climbing a wall. Branches growing away from the structure should be pruned regularly to prevent them from pulling the plant away from the wall.
Final Thoughts
Pruning your climbing hydrangea not only improves its appearance but also encourages healthy growth and more vibrant blooms. With the right care and attention, your climbing hydrangea will continue to thrive, adding beauty and elegance to your garden for years to come.