I have been getting questions about pruning Hydrangeas. It is a little tricky so I guess that is why I hardly ever prune mine. The different kinds of Hydrangeas are pruned differently so I hope this little bit of information will help you make your decisions.
1. Hydrangea macrophylla (Big Leaf, Mophead or Lacecap types) These are often referred to as the “Blue/Pink” varieties because of their change of color dependent on the type of soil. There are enough H. macrophylla cultivars to fill this newspaper. Every plantsman has developed one. They often bloom in early summer and may be still developing flowers in late summer. The buds that produce these flowers are set in the fall. So when do you prune them? I usually prune the flower head stems back to the next bud – that allows the spring blooms to still form. I like to do this as soon as the flower heads turn brown.
If I want to remove some of the older stems or reduce the plant in height, then I wait until late winter – around late February or very early March – then remove about 1/3 of the older stems by cutting them away from the plant at the base of the stem. Leave the younger, but mature stems to bloom the next year. Some cultivars bloom also on new growth. You may have to use your eyes to balance the plant so that all the stems will not come from the same place.
The reblooming cultivar ‘Penny Mac’ is a reblooming Hydrangea and I remember Penny McHenry telling me that she cut hers down totally every late winter, fertilized them with 10-10-10 and gave them copious amounts of water. Many of us remember how beautiful her Hydrangeas were every year. They seemed to bloom on new wood, therefore her namesake, ‘Penny Mac’ blooms on new and old wood.
2. Hydrangea quercifolia (Oakleaf Hydrangea) I hardly ever prune mine – especially the newer cultivars. However, my old ones can get very leggy and have dead stems in them. So I always remove the dead stems and occasionally prune leggy limbs at the base to keep new shoots forming.
3. Hydrangea paniculata (Pee Gee or Panicle Hydrangea). You might have some of these. Common cultivars are ‘Limelight,’ ‘Little Lime,’‘Pinky Winky’ and many others. They bloom on new wood and should be cut back in late winter all the way to the ground or about 18 -24” above the ground. Cutting them all the way back helps to produce the largest blooms, but this can be too much bloom for young stems. Removing flowers as soon as they turn brown will help the shape of this plant.
4. Hydrangea arborescens (Smooth Hydrangea) Treat it just as you did H. paniculata. Cut it back! It only blooms on new wood! ‘Annabelle,’‘Incrediball,’ ‘Limetta’ and other ‘Incrediball’ cultivars. Definitely a winner in the garden.
5. Hydrangea petiolaris (Climbing Hydrangea). Just plant it where it can do its thing – climbing rampantly. If you need to keep it in bounds, prune it immediately after it flowers. Remove any limbs that do not cling.
Please cut this article out and put it on the refrigerator so you can refer back to it when you need to do so. Plant some cultivars that you may not be familiar with. Plant them where they get good sunlight in the morning and shade in the afternoon or in a place of filtered light throughout the day.
Low ph – blue flowers on the blue/pink H. macrophylla cultivars. Add aluminum to get the bluest color. When you add lime and a good bit of it, you raise the pH and you may get purple, then progress to pink. Have fun manipulating the color. Check out Kathy’s Plants on Facebook and make sure to like my page – it has a lot more information.
