Hydrangeas are a beautiful staple of the summer garden and generally require little care once established. Some varieties benefit from regular pruning, others want as little pruning as possible to flower nicely. This month we have some tips to help you determine which types you have and how and when to prune them.
Like other shrubs, hydrangeas of all types should be pruned to remove damage whenever it is noted, and stems that detract from the overall form and crossing branches should be removed yearly. Fortunately, all hydrangeas are pretty tough shrubs, and if you need to prune at the “wrong” time or make a mistake, you’ll only miss one season of bloom.
The climbing hydrangeas (Hydrangea anomela, aka H. petiolaris, and the closely related Schizophragma hydrangeoides) will grow and flower well without any pruning at all. Only when branches grow in undesirable places do they need to be pruned. Climbing hydrangea can reach up to 40 feet, but pruning can be used to maintain a smaller plant. One quirk of climbing hydrangea is their extremely slow growth for the first year or two after planting. It is especially important not to prune them at all at this time.
If pruning needs to be done on an established climbing hydrangea, the best time is late winter or early spring before the leaves emerge. Climbing hydrangeas will respond to renovation pruning if the plant has become straggly or damaged at the top. To renovate, cut back to three or five strong stems, leaving those about three feet long.
Oakleaf hydrangeas are available in several cultivars that mainly differ in mature size, so you can find one that fits your landscape and doesn’t need too much pruning to maintain the desired size. Young oakleaf hydrangeas can (and usually should) be pruned to direct the shape by cutting back by as much a one half after the flowers fade, shaping as needed. Older plants develop wonderful sculptural forms, and only need pruning to remove damage or poorly placed branches that detract from the overall shape, but can also be pruned by up to one half if needed to control size.
Oakleaf hydrangea flowers can be cut to enjoy indoors without harming the next year’s bloom, either while fresh or after the flower heads have naturally dried on the plant to a buff-tan color.
Smooth hydrangea, or Hydrangea arborescens is probably best known by the cultivars ‘Annabelle’, ‘Incrediball’, and ‘Invincibelle Spirit’. It will rebloom through the summer on new growth and can be used as a cut flower.
Yearly pruning is recommended for smooth hydrangea to keep growth neat. The entire shrub can be cut to the ground anytime from fall to late winter, or stems can be left 1 to 2 feet long. Leaving the partial stems rather than cutting to the ground can give you stronger stems that remain upright better after heavy rains, but some people don’t like the look of the bare stems in winter.
The paniculata hydrangeas (‘PeeGee’, ‘Tardiva’ and ‘Limelight’ are a few examples) are about as fool-proof as a hydrangea can get, with sturdy strong stems that bloom on the current year’s growth.
They can be pruned winter or early spring for a tidy appearance, but annual pruning is not necessary for good flowering. Paniculatas can be pruned to the ground, or you can leave 1 to 3 feet of stem for a taller plant. If you have a tree form paniculata hydrangea, prune to within a few inches of the previous year’s pruning cuts in early spring to keep branches sturdy and able to support the flowers. Like all hydrangeas, paniculatas make great cut flowers and can be cut at whatever flower stage you desire for display.
The hydrangeas that people have the most questions about pruning are the macrophylla or big leaf hydrangeas. These are the hydrangeas that flower blue or pink and in either mophead or lacecap forms. The key to macrophylla hydrangeas is to prune almost never if possible.
Try to purchase macrophylla hydrangeas that fit your available space at maturity and will not grow to a size that needs to be kept in check. Most will be about 3 to 5 feet tall and wide, but dwarf forms (under 3 feet) are available. If you already have a macrophylla that is too large for its space, prune to size immediately after flowers fade to avoid cutting off next year’s blooms, which form in late summer.
Otherwise, the recommended pruning for macrophylla hydrangeas is to only remove dead wood (easiest to see in early spring just as leaves begin to unfold—the parts of stems where leaf buds fail to swell are dead and can be removed safely) and, on older plants, up to one third of the older stems can be removed to the ground to keep the shrub vigorous. That’s it!
If you like to use macrophylla hydrangeas as cut flowers, until August you can cut as long of a stem as you need without affecting next summer’s blooms. After that, or to remove old flowers, cut flowers only to the first set of big leaves. The exceptions are ‘Endless Summer’ family of hydrangeas and the other “everblooming” hydrangeas that are forgiving of later pruning, as they flower on old and new growth. Removing fading flowers on these everbloomers will encourage more flowers the same summer.
For general pruning tips that you can apply to hydrangeas, see our Pruning Basics info sheet.
For more information on hydrangeas (including why they're not blooming, and changing the color), see our Hydrangea Q&A info sheet.
Hyrdangea anomela by A. Barra (Own work) [GFDL or CC BY 3.0], via Wikimedia Commons
Hydrangea quercifolia by Eric in SF (Own work) [CC BY-SA 3.0 or GFDL], via Wikimedia Commons
Hydrangea arborescens by KENPEI (KENPEI's photo) [GFDL, CC-BY-SA-3.0 or CC BY-SA 2.1 jp], via Wikimedia Commons
Hydrangea paniculata by Frank Vincentz (Own work) [GFDL or CC-BY-SA-3.0], via Wikimedia Commons
Mophead hydrangea by Raul654 [GFDL or CC-BY-SA-3.0], via Wikimedia Commons
Lacecap Hydrangea public domain, via Wikimedia Commons