Pruning hydrangeas is essential for maintaining their health, encouraging robust growth, and enhancing their flowering potential. However, understanding when and how to prune hydrangeas can be challenging due to the variety of species and their different pruning needs. Here’s a comprehensive guide to everything you need to know about pruning hydrangeas.
1. Know Your Hydrangea Type
Hydrangeas can be broadly categorized based on their pruning requirements into two groups:
- Hydrangeas that bloom on old wood: These types include Bigleaf (Hydrangea macrophylla), Oakleaf (Hydrangea quercifolia), Mountain (Hydrangea serrata), and Climbing hydrangeas. They produce flower buds on stems that have been on the plant since the previous summer.
- Hydrangeas that bloom on new wood: These types include Panicle (Hydrangea paniculata) and Smooth hydrangeas (Hydrangea arborescens). They produce flowers on the current season’s stems.
2. When to Prune
- Old Wood Hydrangeas: Prune these right after they bloom in the summer but no later than August. This gives them time to develop buds for the next season.
- New Wood Hydrangeas: Prune these in late winter or early spring before new growth starts. This timing helps encourage vigorous growth and abundant blooms.
3. Pruning Techniques
- General Pruning: Regardless of type, remove dead stems and spent blooms from all hydrangeas. Also, cut away any crossing branches to maintain good air circulation.
- Pruning Old Wood Hydrangeas: Lightly prune these to shape the plant and encourage next year’s blooms. Be careful not to cut too many of the old stems, as this can reduce flowering.
- Pruning New Wood Hydrangeas: These can be cut back more drastically, up to one-third of their total height. This promotes a sturdier plant that can support more and larger blooms.
4. Deadheading and Maintenance
- Deadheading: Removing old blooms can promote reblooming in many hydrangea varieties. For bigleaf hydrangeas, cut the spent bloom just above the first set of full leaves below the flower head.
- Maintenance Pruning: Throughout the growing season, prune out weak or dead stems that can drain energy from the plant and encourage disease.
5. Pruning Climbing Hydrangeas
Climbing hydrangeas require less pruning than their bush counterparts. Prune to control size and remove any dead or overly crowded branches. It’s best to do this just after flowering to avoid cutting off next year’s buds.
6. Common Mistakes to Avoid
- Over Pruning: This can stress the plant and reduce flowering. Always know the specific needs of your hydrangea type.
- Late Pruning: Pruning too late in the season can remove flower buds and leave hydrangeas bloom-less for a year.
- Ignoring Plant Health: Always use clean, sharp pruning tools to make clean cuts and avoid spreading diseases.
7. Aftercare
Following pruning, apply a balanced fertilizer to encourage growth. Water regularly, especially if you’ve made extensive cuts, to help the plant recover and thrive.
Conclusion
Understanding the specific pruning needs of your hydrangea type is crucial to achieving beautiful blooms and a healthy plant. By following the correct pruning time and techniques for your hydrangea, you can ensure your shrubs are both a visual delight and vigorous growers year after year.