When to Trim Hedges in Canada
Spring and midsummer for most hedges, the one rule that keeps the bottom green, and why the last trim has to come well before fall.
When to trim hedges in Canada is twice a year for most hedges: once in spring and again in midsummer. The University of Minnesota Extension gives exactly that schedule for keeping a hedge dense and attractive.
The date that matters most is the last one. A trim late in the season pushes out soft new growth, and that growth needs weeks to harden before the first fall frost.
Hedges at a glance: trim in spring and again in midsummer. Once the hedge is at its height, trim the new growth when it reaches about 15–20 cm, back to within about 5 cm of the last cut. Keep the hedge wider at the bottom than the top. Finish by midsummer; for junipers, do not prune after August.
Have a cedar hedge? See When to Prune in Canada for cedar, juniper and yew timing.
The Schedule
Minnesota’s guidance for an established hedge: once it reaches the height you want, trim the new growth whenever it has grown another 15–20 cm, cutting back to within about 5 cm of the previous trim. Two trims a year, spring and midsummer, keeps most hedges dense.
Wisconsin, writing about sheared evergreen hedges, says to leave about 2.5 cm of the previous growth each time so the plant can regrow from it.
Finish Before the Season Turns
A trim stimulates new shoots. Late in the season those shoots do not have time to harden, and winter browns them. Wisconsin gives a firm date for one group: do not prune junipers after August. For most hedges, the midsummer trim should be the last one.
How much time you have depends on where you live. These are each city’s average first fall frost:
| City | Zone | Avg first fall frost |
|---|---|---|
| Vancouver | 8b | Nov 30 |
| Toronto | 6b | Nov 1 |
| Ottawa | 5a | Oct 12 |
| Montreal | 5b | Oct 7 |
| Halifax | 6a | Oct 18 |
| Winnipeg | 3a | Sep 20 |
| Calgary | 3b | Sep 21 |
| Edmonton | 4a | Sep 23 |
The frost dates are Environment and Climate Change Canada normals. The earlier your first frost, the earlier your last trim.
Wider at the Bottom
Both Minnesota and Wisconsin give the same rule: trim the hedge so it is wider at the base than at the top. That lets sunlight reach the lower branches. A hedge cut straight-sided or wider at the top shades its own base, and the bottom goes bare.
Deciduous Hedges vs Evergreen Hedges
| Hedge | When | Note |
|---|---|---|
| Deciduous (privet, alpine currant, ninebark, lilac, spirea) | spring, then midsummer | Spring-flowering hedges flower more if the spring trim waits until just after bloom. |
| Cedar, yew, hemlock | spring through midsummer | They grow all season and can be sheared, per Minnesota and Wisconsin. |
| Juniper | summer tip pruning only | Never cut back into bare, needle-less wood, and not after August (Wisconsin). |
For cedar hedges in detail, see when to prune cedar hedges.
Planting a New Hedge
Minnesota says that when you plant deciduous shrubs for a hedge, you cut each plant back to within about 15 cm of the ground. It feels drastic, but it makes the hedge branch out from the bottom, which is what keeps it full for years.
Shears or Pruners
Hedge shears are for hedges and nothing else, Minnesota notes. A formal hedge is meant to be sheared; a shrub border is not. For a shrub that has become a tangle, see how to prune overgrown shrubs.
Frequently Asked Questions
When should I trim my hedge in Canada?
Twice a year for most hedges: in spring and again in midsummer. Make the midsummer trim the last one so new growth hardens before the first fall frost.
Can I trim a hedge in the fall?
It is better not to. A late trim pushes out soft new growth that winter can brown. Finish by midsummer.
How much should I cut off a hedge?
Once it is at its height, trim the new growth when it reaches about 15 to 20 cm, cutting back to within about 5 cm of the last trim.
Why is the bottom of my hedge bare?
The hedge is probably wider at the top than the bottom, so the top shades the base. Trim it so it is wider at the bottom.
When should I trim a juniper hedge?
Tip prune in summer, and not after August. Do not cut back into bare wood, because junipers do not regrow from it.
How do I start a new hedge?
When planting deciduous shrubs for a hedge, cut each one back to within about 15 cm of the ground so it branches from the base.
Sources
- University of Minnesota Extension — Pruning trees and shrubs (reviewed 2026)
- University of Wisconsin–Madison Extension — Pruning Evergreens
- University of Wisconsin–Madison Extension — Pruning Deciduous Shrubs
- Environment and Climate Change Canada — Canadian Climate Normals (the frost dates in the tables, read from this site’s frost data)