Of all the classes that we offer here at the nursery, pruning is always the most popular. And, of all the different types of plants that need to be pruned, hydrangeas are probably the most confusing. Hopefully, I can help clear the air on how to properly prune these extremely popular shrubs.
First off, hydrangeas do not have to be pruned if they are planted in the right location where they can be allowed to grow to a mature size, which of course can vary depending on the cultivar. For a mature hydrangea, all that is required to keep it looking tidy is to remove the spent flowers sometime before spring.
Most hydrangeas fall into two categories. The most popular flavor is the shade-loving bigleaf or mophead variety that sports large ball-shaped flowers or flat delicate ones called lacecaps. These come in shades of pink to dark purple and a few that are pure white. Traditional varieties of this type of hydrangea should not be pruned, except to remove spent flowers or an occasional errant branch. The reason is that the flower buds are formed on the previous season’s growth (we call that old wood). If you prune those stems back more than a node or two (a node is where a set of leaves was attached), you will remove next years flowers. This is probably the primary reason why hydrangeas don’t bloom. If you have to prune your hydrangea to make it fit into where it is planted, then you will constantly be faced with this dilemma. The solution is to remove your plant and replace it with one of the many new forms that are dwarf and only grow to 3 to 4 feet tall. There is actually a fully dwarf model call ‘Pia’ or ‘Pink Elf’ that only reaches 18 to 24 inches tall.
The second most popular form of hydrangea is the sun loving “panicle” type, which has large fluffy cone-shaped flowers that start out white or lime-green and mature to wonderful shades of pink to rusty red. These hydrangeas bloom on current season growth (we call this new wood), so just like a rose, we can whack the heck out of them if we want to and they will always reward us with lots of blooms later in the summer. Again, you don’t have to prune them, but if you do, you will get larger flowers, albeit fewer, than if you just let them go.
Just to confuse the issue, new developments in breeding have brought us repeat blooming forms (called remontant) of the bigleaf varieties that bloom both on last year’s wood in late spring and again on current season’s wood in late summer. ‘Endless Summer’ is probably the most recognized brand with its blue plastic pots. The beauty of these new hydrangeas is that if you screw up (or Mother Nature is naughty and freezes off all the buds), you will still get flowers later in the year. That being said, it is still best to keep your pruning to a minimum and focus on only removing spent flowers and a little shaping. Almost all of the new bigleaf varieties now on the market are repeat blooming and compact growers - which is great news for all of us.
Bottom line, the secret to successful pruning of hydrangeas is to recognize what kind you have and where the flower buds are formed, last year’s wood or current season’s wood. For more info on growing hydrangeas, I highly recommend the website from Proven Winners. They have done a very thorough job of demystifying the art of growing hydrangeas. Stay safe and keep on gardening!
