WHEN TO PRUNE small trees and shrubs depends on when they flower. Plants grown primarily for early spring flowers (on the previous year's growth) should be pruned immediately after they finish blooming. This includes azaleas, forsythias, pearl bush, flowering plums, crabapples, and redbuds. Fruit trees are best pruned in late winter, before they begin new growth.
Shrubs grown primarily for their foliage, rather than showy flowers, should be pruned in spring before growth begins. This includes dogwood, honeysuckle, barberry, alpine current, purpleleaf sandcherry, smokebush, and buffaloberry.
Shrubs that bloom on new growth may be pruned in spring before growth begins. Plants with marginally hardy stems such as clematis and shrub roses should be pruned back to live wood. Hardier shrubs such as late blooming spireas and smooth (snowball) hydrangeas should be pruned to the first pair of buds above the ground.
PRUNE OLDER or overgrown shrubs every year by removing up to one-third of the oldest, thickest stems or trunks, taking them down to the ground. This will encourage the growth of new stems from the roots. Once there are no longer any thick, overgrown trunks left, switch to standard pruning as needed.
Honey Rose* 1994 showy flowers, good for tough sites in southwestern Minnesota
Freedom* 1986 resistant to witches broom aphid, recommended for windbreaks
Pearlbush, Exochorda serratifolia
Northern Pearls* 1995 attractive flowers, showy exfoliating bark, 10'
Red Osier Dogwood, Cornus sericea
Cardinal* 1986 young growth has bright red winter color for winter interest
Isanti* 1971 compact selection of C. sericea, tolerates poorly drained soils
Northern Sun* 1982 very hardy flowerbuds, fast growing, 8-10', tolerates a wide range of soils
Emerald Triumph* 1994 showy clusters of white flowers in mid-May
Jack Pine, Pinus banksiana
Uncle Fogey* 1971 selection with prostrate, drooping habit, 6'
Red Pine, Pinus resinosa
Wissota* 1996 dwarf form, 6'
L.E. Longley 1949 hybrid tea
Pink Rocket 1949 shrub
Prairie Fire 1959 shrub
Red Rocket 1949 shrub
Viking Queen 1963 large flowered climber
White Dawn 1949 large flowered climber
*=varieties available from retail nurseries, those without are heirloom varieties with limited availability
'Isanti' is a slower growing selection of native dogwood. 'Cardinal' was introduced for its vivid red winter twig color. Both grow well in full sun or partial shade and tolerate poorly drained soils.
'Northern Pearls' is the only selection of pearlbush hardy for Minnesota. It can be pruned to a single trunk for a small tree, or grown as a shrub. Showy white flowers — two inches across — appear early in May.
'Honey Rose' honeysuckle flaunts showy pink flowers in late May.
'Northern Sun' forsythia is hardy to -30 degrees, and after winter its showy yellow flowers are a welcome April sight.