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Pruning Tips

Oct 25, 2013

Confused about when to prune? Allow us to demystify this for you. Follow these pruning guidelines that are based on flowering times, leaf structure (evergreen or deciduous) or time of year:

Perennials: remove/deadhead old flowers as needed although some perennials are free-flowering and don’t require deadheading (coreopsis, blue plumago, sedum). Once frost has browned their leaves, cut non-evergreen perennials to the ground and remove the debris. Liriope, sedges and ornamental grasses often keep their shape and offer some color through the winter so cut these to the ground in early to mid-March before new growth emerges.

Generally speaking, it’s usually not a good idea to prune shrubs and trees in the fall because pruning triggers a flush of new growth that can be damaged from freezing weather, and if the plant blooms on old wood you’ll be pruning off next year’s flowers. Wait until mid-winter when the plant is dormant to prune plants that form blooms on new wood, and wait until just after the plant blooms to prune plants that set their buds on old wood.

Shrubs: prune shrubs that bloom in the spring to early June right after they flower since they set next year’s buds on new growth made after they flower (forsythia, lilac, azalea, rhododendron, spirea, viburnum, etc). Shrubs that bloom in the summer and fall should be pruned in late winter to early spring so they have enough time to set their flower buds and then flower (butterfly bush, caryopteris, crapemyrtle, fall camellia, etc). Prune hydrangeas down to live wood or to the shape you want in the early spring. Nandinas should be pruned in the spring if the foliage is damaged in the winter.

The candles (new growth) of needled evergreens that don’t bloom and only produce terminal buds (pine, spruce, fir, etc) should be pruned in half in the spring when the candles have reached 2”- 4” in length. Needled evergreens like hemlock, arborvitae, falsecypress and yew can be pruned severely in the spring or trimmed throughout the year as needed, although pruning between October to early December is not advisable since any new growth won’t have time to mature and harden off before the winter. Broadleaved evergreens like hollies and cherrylaurels can be pruned as needed, but refrain from pruning in October and November for the reasons stated above.

Trees that run sap in early spring (dogwood, maple, birch, sophora, etc) should ideally be pruned in late November to early December, or late summer during July and August.

Prune spring flowering trees (cherry, purple plum, Bradford pear, etc) after they flower. If you prune at other times you might remove next year’s blooms. Summer and fall blooming trees (crapemyrtle, stewartia) should be pruned in late winter to early spring. Shade trees (oak, linden, ash, etc) can be pruned any time although winter is the best time to prune them since you can see their branching habit.

Hope this helps. Call us if you need help with your garden maintenance or if you need a spruce-up for a party or special event. We can design a maintenance package that’s tailored to your garden needs with yearly, quarterly or monthly visits.