If you’ve ever developed a hydrangea shrub (Hydrangea spp.) , you are likely familiar with their large and striking flower clusters that can resemble softballs or large pyramids, based on the variety. Hydrangeas can be tall and large, but they also come in dwarf varieties, with a compact, shorter growth habit that still brings a showy display of flowers. Dwarf hydrangeas are generally bushy and well-shaped, and don’t require regular pruning, but you might want to give a plant a trim to improve its physical appearance or remove damaged branches.
Making the Decision
Even though a dwarf hydrangea can thrive without pruning, if it’s outgrowing its spot in the backyard or in case divisions are protruding outside the canopy, you can trim these back to improve the shrub’s appearance or keep its size in check. Trim branches with sharp pruners, cleaning your blades by wiping them in rubbing alcohol between cuts to discourage spread of plant diseases. When trimming divisions to control a plant’s size and encourage bushiness, cut several branches back by approximately one-third in one pruning session, repeating this each season until you’ve trimmed all the branches. If your hydrangea is older and blooming poorly, you can rejuvenate the entire plant by cutting off one-third of those divisions at ground level in each of three consecutive years. If storms damage branches on a dwarf hydrangea, splintering or bending them, trim them as soon as they appear, making a slanted cut behind the damaged area and into healthy wood.
Pruning in Summer
The best time to prune a dwarf hydrangea depends to some degree on the species, especially if you’d like to have as many flowers as possible throughout the next blooming season. For instance, some types bloom on old wood, forming buds for the following season’s flowers in summer or fall. To enable buds to form on such dwarf hydrangeas, do all pruning immediately after flowers fade, usually by mid-July or even August. This is also the best time for deadheading, or removing spent flowers to improve the plant’s appearance. Hydrangeas that bloom on old wood include dwarf varieties of bigleaf hydrangeas (Hydrangea macrophylla) like the cultivar “Pia” (Hydrangea macrophylla “Pia) and plants in a series called “Cityline”; illustrations in the series include “Cityline Paris” and “Cityline Vienna.” All these dwarf bigleaf shrubs develop in U.S. Department of Agriculture plant hardiness zones 5 through 9.
Pruning in Fall or Winter
If you are growing a dwarf type of panicle (Hydrangea paniculata) or even smooth hydrangea (Hydrangea arborescens), these types bloom on new wood, from buds that form in early spring, so trim these plants back in autumn or even in late winter, before new growth begins. Pruning sometimes doesn’t interfere with spring development and allows the plant to come up with the most number of fresh flowers. Dwarf cultivars of these types include two white-flowered shrubs, one called “Bobo” (Hydrangea paniculata “Bobo,” USDA zones 3 through 9) and a second called “Incrediball” (Hydrangea arborescens “Incrediball,” USDA zones 4 through 9).
Care After Pruning
Whenever you prune your dwarf hydrangea, a little extra care later can help the plant set out healthy new development. Keep the shrub well-watered for a month or 2 after pruning, aiming for at least 1 inch of water per week, like rain. Insert a 3-inch layer of organic mulch like straw or shredded bark under the plant’s canopy, to help preserve soil moisture and keep down weeds, but keep the mulch back several inches from the central stems to discourage fungal development. If your area is prone to strong end, give the plant with some shelter to protect against drying out of fresh development. Drive several stakes into the ground around the plant, about 1 foot away from the own canopy, and staple burlap into the stakes, to supply a wind shied, keeping this in position for many months until new beginnings strengthen.