What is the spring pruning schedule for common NB shrubs and trees?

The spring pruning schedule for New Brunswick shrubs and trees follows one fundamental rule: prune spring-flowering plants AFTER they bloom, and prune summer-flowering plants BEFORE they leaf out in early spring. Getting this wrong — particularly pruning spring bloomers in early spring — is the most common pruning mistake NB gardeners make, and it eliminates that year's entire flower display because spring-flowering plants set their buds the previous fall.

March is the time for dormant pruning of deciduous trees and summer-flowering shrubs. While NB is still firmly in winter, the sap hasn't started flowing yet, and the bare branch structure lets you see exactly what you're cutting. Prune maples, birches, and oaks during March dormancy to minimize sap bleeding and disease risk. Summer-flowering shrubs that bloom on new wood — including panicle hydrangeas (Hydrangea paniculata), Rose of Sharon, potentilla, and spiraea (Anthony Waterer and Goldflame types) — should be pruned hard in March to encourage vigorous new growth that produces flowers later that summer. Cut these back by one-third to one-half of their total height.

April brings the pruning window for roses and some broadleaf evergreens. Once you see buds starting to swell on rose canes — typically mid to late April in the Moncton area, late April in Fredericton — prune back to the highest outward-facing healthy bud. Remove any canes that are dead (brown or black), damaged, or crossing other canes. For broadleaf evergreens like boxwood and holly, do light shaping in late April before new growth begins.

May through June is when you prune spring-flowering shrubs and trees — but only AFTER their blooms have finished. Forsythia (which blooms in early May in NB), lilacs (mid to late May), rhododendrons (late May to June), and flowering crabapples should all be pruned within 2-3 weeks after their flowers fade. This gives the plant the maximum time to set next year's flower buds over summer. If you wait until late summer or fall to prune these, you'll cut off next spring's developing buds.

Specific NB timing for common species: Prune lilacs immediately after flowering in late May, removing spent flower heads and thinning one-third of the oldest stems to ground level. Prune forsythia right after bloom in mid-May by removing one-quarter of the oldest canes at the base. Prune rhododendrons after flowering in June by snapping off spent flower trusses carefully without damaging the new growth buds just below. Prune cedar hedges (arborvitae) in late June when new growth has emerged but is still soft.

Never prune during active spring leaf-out (typically late April to mid-May in NB), as this is when trees are most vulnerable and diseases spread most easily. Also avoid pruning birch and maple trees after early March, as they bleed sap heavily once the sap starts running. Professional pruning services in NB charge $150-500 for shrub pruning and $300-1,500+ for tree work depending on size and accessibility.

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