Proper pruning technique will keep your shrubs healthier, encourage blooms and manage shape and size. Early spring is a great time to get started.
Broken, damaged, diseased or branches that rub together should be removed whenever you see them.
• Branch by branch shaping: Cut back longer branches to the crotch or a bud, maintaining the natural shape of the shrub.
• Thinning: Remove about 1/3 of the branches each year back to the crotch of those branches; select larger branches for pruning. Promotes blooms and new growth, and controls woodiness.
• Renewal pruning: For summer-blooming shrubs (those that bloom after June 15). Only on new growth. The shrub is cut back to 8 to 12 inches from the ground; leave one or two leaf buds at the base of the stem in late winter. Candidates for annual renewal pruning include butterfly bush, except for silver fountain butterfly bush, blue mist spirea, Russian sage and barberry.
An alternative to annual renewal is to complete the process over a three-year period,.The difference between three-year renewal and thinning is that you cut back almost to the ground, not just to the crotch to renew.
• Rejuvenation: This is the most drastic of approaches usually reserved for seriously overgrown shrubs. The shrub is cut back almost to the ground. It is an alternative to rescue a shrub that otherwise might need replacement.
• Spring-blooming shrubs (those that bloom prior to June 15 on last year’s growth) can be pruned using any of the techniques listed here. Pruning generally is done immediately after bloom. Pruning in late winter or spring will likely not harm the plant, but will reduce the blooms for that season.
Cuts should be made just above a bud or leaf or at the crotch of the branch.
• A 45-degree angle parallel to the stem bud or leaf is ideal.
• Use the correct-size tool with a sharp blade to make a clean cut.
Late winter early spring:
• Summer-blooming shrubs.
• Candidates for radical surgery (rejuvenation).
• Junipers and arborvitae. Snip back new growth to an upward growing side branch to maintain natural shape. Do not cut back to wood.
Midspring to early summer:
• Spring bloomers right after bloom.
• Broadleaf evergreens like boxwood, holly and Oregon grape holly, late April to mid-May, do not prune after July.
• Roses, late April to mid-May.
• Pines. Using the fingers, snap off one-third of the new growing tips while in the “candle” stage (in the spring when young needles are in a tight cluster).
When you have questions, Colorado State University Extension has research-based answers. Get answers to your horticulture questions by visiting ask.extension.org any time day or night. Follow the El Paso County Master Gardeners on www.facebook.com/ColoradoMasterGardeners.EPC/.