The short answer
A hedge must be wider at the base than the top. Cut it straight-sided or wider at the top and the bottom is permanently shaded — it thins, goes bare, and on many species will not recover, because they don’t reshoot from old wood. That taper is the single most important thing about hedge cutting and almost nobody mentions it.
Shape
Wider at the base
Why
Shading kills the bottom
Timing
Flowering habit decides it
Old wood
Some species never reshoot
When to cut, by flowering habit
Get this wrong and you remove a year’s flowers. It’s not harmful, just disappointing and avoidable.
Cut after flowering
Spring flowering
Sets buds on last year’s wood. Cutting in late winter or early spring removes the flowers before they open. Trim straight after it finishes blooming.
Cut in late winter
Summer flowering
Flowers on the current season’s growth, so a hard cut before growth starts gives more flowers rather than fewer.
Careful
Conifers
Most will not reshoot from bare old wood. Cut back past the green and that section stays brown permanently. Trim little and often, never hard.
Check first
Nesting season
In many jurisdictions it’s an offence to damage an active nest. Check before cutting anything substantial in spring or early summer, and look before the blades go in.
Why the taper matters so much
A hedge is a plant, and plants grow toward light. Cut a hedge with vertical or overhanging sides and the top shades the bottom continuously. The lower growth weakens, thins and eventually dies back to bare stems.
On species that reshoot readily — privet, beech, hornbeam — you can recover it over a few seasons of hard renovation. On conifers, mostly you can’t. Bare is permanent, and the only fix is replacement.
The taper needed is slight — a few degrees, so the base is noticeably wider than the top. It looks almost vertical when done correctly, and it keeps light on the lower growth for the life of the hedge.
Cutting it properly
Ground-level work on anything you can reach standing. Straightforward, and worth doing right.
Check for nests first
Look before the blades go in, at any time in spring or early summer. In many places disturbing an active nest is an offence.
Set a line for the top
String between two canes. Freehand tops wander, and a wavy hedge is obvious from a distance and hard to correct.
Cut the sides first
Bottom to top, tapering inward as you rise. The base should end up noticeably wider than the top.
Then the top
To the line. Doing the top first means the debris hides the sides you haven’t cut.
Take less than you think
Especially on conifers. You can always cut again in a fortnight; you can’t put it back.
Clear the clippings out
Off the top of the hedge and out of the base. Left in, they rot in place and damage the growth beneath.
Renovation potential by type
Where this stops being a DIY job
Anything needing a ladder with a powered trimmer. A hedge trimmer takes two hands and a stable stance. On a ladder you have neither, and the blade is at chest height.
Hedges over about head height. Beyond that it’s platform work, and the reach also makes an even cut genuinely difficult.
Renovating a badly overgrown conifer hedge. Whether it can be reduced at all depends on the species and how much green remains. Cutting first and finding out afterwards leaves you with brown walls and a replacement bill.
What a competent hedge cut looks like
Shapes
Tapers the sides
Base wider than top. The clearest single marker of someone who knows hedges.
Times
Asks what species
Flowering habit decides the month. A crew cutting everything in one visit isn’t working to the plants.
Checks
Looks for nests
In season, before starting. It’s a legal obligation in many places.
Common questions
Why is my hedge bare at the bottom?
Almost always because it’s been cut with vertical or overhanging sides, so the top shades the base. Hedges need to be wider at the bottom than the top.
When should I trim my hedge?
Depends on flowering habit. Spring-flowering species should be cut straight after they finish; summer-flowering ones can be cut in late winter. Conifers want little and often.
Can you cut a conifer hedge back hard?
Generally not. Most conifers won’t reshoot from bare old wood, so cutting past the green leaves a permanent brown patch. Yew is the notable exception.
Is it illegal to trim hedges in nesting season?
In many jurisdictions it’s an offence to damage an active nest. Check what applies locally and look carefully before cutting in spring or early summer.
Above head height, or already gone bare?
Anything you can reach standing on the ground, cut with a tapered profile at the right time of year, is genuinely yours and it’s most hedges. A trimmer on a ladder is the combination to avoid, and renovating an overgrown conifer is a decision worth an opinion before the blades go in.
Call (877) 360-4657