It’s late March and if you’re like most Nebraskans who tend to their landscape, you’ve been looking out the window all winter and wondering if it is time to prune the shrubs. It might be…depending on the shrub. This handy chart will steer you in the right direction.
Prune Now: privet, burning bush, spirea, mockorange, rose of Sharon, sumac
Why? These shrubs either bloom on current (2020) wood in mid-summer or don’t bloom much at all, being grown mostly for foliage appeal. Current wood bloomers will respond readily from thinning and benefit from the dead wood removal and increased air flow.
Prune After Flowering: lilac, dogwood, quince, viburnum, forsythia, plum, cotoneaster, pyracantha
Why? These shrubs bloom on last year’s wood (2019). Thinning and heading back will remove the tissue that will produce the flowers that offer great color and texture appeal.
Prune After Growth Flush: yews, boxwood, holly, Oregon hollygrape.
Why? These shrubs are not grown for flowers and are more easily managed by keeping them in the desired size range by thinning, not shearing, soon after they put out their new growth for the year.
Thinning vs. shearing – Thinning, removing the oldest stems at the ground level, is MUCH preferred to shearing (cutting off all stems at a predetermined height). Thinning encourages new growth near the base of the plant, removes insect pests such as borers and scale and dead stems and increases the air flow through the plant, which discourages foliar diseases.
Shearing produces a nice, clean look, but does so at the expense of form, vigor and health of the shrub. Most shrubs that have been pruned with a shearing regime develop a rounded top, thin foliage at the base, patches of dead foliage in random places in the canopy, encroachment onto sidewalks and patios and pests mentioned earlier.
Basal pruning – either after flowering or in late winter/early spring, removing all stems at the base of the shrubs is a good way to renew an older, nonproductive shrub. With this method, the new growth will make up the canopy and allow the opportunity to produce a healthy, natural shape. This method delays blooming for a year or two for flowering shrubs.