Do you dream of a garden where every shrub is bursting with vitality and flowers? Pruning is the secret tool to make it happen! It controls your plants' development, rejuvenates them, and most importantly, stimulates a generous bloom season after season. But be careful: the timing of the cut is crucial, especially in Quebec.
Pruning at the wrong time can cost you all your flowers. To never make a mistake, follow the golden rule: the ideal time depends on whether your shrub flowers on last year's wood (old wood) or on new growth (new wood).
Note that the periods indicated (late May, early April) are averages. The colder your zone (e.g., Zone 3), the later these dates will be, as they depend on the snowmelt and the start of the growing season.
For more detailed explanations on this fundamental distinction and on specific techniques, check out our articles: The Secret to Abundant Blooms: Prune Flowering Shrubs and Pruning Types for Trees and Shrubs.
Spring-Flowering Shrubs: Prune After the Show
These shrubs, like lilacs and forsythias, bloom on the stems formed the previous year ("old wood"). If you prune them in the spring before the flowers appear, you are simply cutting off all the flower buds formed the previous summer! This guarantees a season without blooms.
When to Prune?
- Immediately after the blooming period ends.
- Depending on the species and region, this is generally from late May to mid-June.
- Pruning at this time allows the shrub all summer to produce new growth and form the buds that will flower the following spring.
Common Examples
Lilac, Forsythia, 'Snowball' Viburnum, Weigela, Van Houtte Spirea (Spiraea x vanhouttei).
Summer or Autumn-Flowering Shrubs: Prune Early in Spring
These shrubs, including many hydrangea varieties, bloom on the new growth of the current year ("new wood"). Spring pruning is not only safe, but it's necessary to stimulate vigorous growth and an abundant bloom.
When to Prune?
- Early spring, before the buds break dormancy.
- Generally, in October or April and May (depending on the zone and snowmelt).
- Pruning in early spring removes old wood and encourages the plant to produce new stems that will bear the summer flowers.
Common Examples
Panicle Hydrangea (H. paniculata) and arborescens, Potentilla, Japanese Spirea (S. japonica / bumalda), Reblooming Hardy Roses, Ninebark.
Ornamental Foliage or Stem Shrubs: Focus on Intense Colors
For shrubs whose main appeal is their colored foliage (e.g., certain Ninebark, Elderberry, Willow varieties) or vibrant winter stems (Dogwoods), the goal of pruning is to stimulate the growth of new shoots, as they often offer the most intense colors.
When to Prune?
- Early spring, before the buds open (April-May).
Common Examples
Ornamental Dogwoods (Cornus alba, C. sericea), Colored Foliage Ninebarks (e.g., 'Summer Wine', 'Diabolo'), Ornamental Shrub Willows (Salix integra 'Hakuro Nishiki'), and Cutleaf or Purple Elderberries.
Essential Pruning Any Time of Year
Whether your shrub flowers on old or new wood, there is one pruning rule that applies at all times:
- Remove damaged branches, dead wood, diseased stems, or crossing branches.
- This cleaning cut promotes the plant's health and vigor and can be done at any time of the year as soon as the problem is identified.
Important Safety Rule
To avoid weakening your shrub, never prune more than 30% of the old growth in a single year. Aim for gradual renewal to maintain long-term vigor.
The Right Tool for the Right Cut and Safety
A successful prune starts with the right tool. Use bypass pruners for branches less than 1.5 cm in diameter, loppers for diameters up to 4-5 cm, and a pruning saw for larger stems.
For your safety, always handle pruning tools with care. Wear sturdy gloves and safety glasses to protect yourself from debris. Disinfect your blades after cutting diseased wood to avoid spreading infections.
When in Doubt, Consult Our Experts!
Every shrub has its unique characteristics. If you are unsure of the ideal time to prune a specific species or if you are hesitant about the cutting technique (thinning, rejuvenation), do not hesitate to consult our experts at the garden center. We are here to guide you!
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