Following these great tips for pruning your hydrangeas can mean the difference between beautiful flowers and none at all. The key to pruning correctly is knowing what kind of hydrangea you have and whether it produces flowers on old or new wood. If you’re having trouble identifying which kind you have, take a cutting to your local nursery or cooperative extension center.
This type includes the oak leaf varieties, easily identified by their oak-shaped leaves, and the popular macrophylla varieties mophead and lacecap. These types can flourish without any pruning at all and will often not require any until they are very mature, at which point their stems may be so long they start to flop over. Because pruning this type of hydrangea is the trickiest, it’s best to plant them in an area large enough to accommodate the shrub’s mature size.
Old-wood bloomers are best pruned immediately following bloom, before they set buds for next year’s flowers. A few of the oldest and/or weakest canes can be removed at ground level every year or so to improve the shrub’s vigor. Dead wood can be removed at any time. Deadheading, or removal of spent flowers, can also be done at any time, making cuts either just above the first set of big leaves or just above the next healthy bud to be sure you’re not cutting off any flower buds.
“Smooth” or arborescens hydrangea and panicle hydrangeas bloom on this year’s growth and are therefore best pruned in late winter or early spring. The only time not to prune is in summer, right before flowering. While most hydrangeas don’t require pruning to maintain an attractive shape, pruning will result in larger flowers. It will also result in weaker stems, however, that are less able to hold up the flowers. New-wood bloomers can be cut back aggressively, but it’s best to leave about eighteen to twenty-four inches of old growth to help support the large blooms. Removal of dead wood and spent flowers can be done at any time.