How do I prune a new hedge in its first few years?

Almost every bare-bottomed hedge in Britain was made in its first three years. Left to grow, hedging plants race upwards with a single leader and put nothing into low side branches, and by the time the owner notices, the wood at the base has no buds left to shoot from. Formative pruning trades height in years one to three for density for the following forty.

What you'll need

• Secateurs and shears
• String line and canes
• Loppers (optional)

Step by step

1. Cut back hard at planting.Reduce most deciduous hedging by about a third at planting. Hawthorn, blackthorn and privet can go harder, to around 150 to 300mm from the ground, which produces a thicket of low shoots. Evergreens and conifers are the exception — do not cut the leader on a conifer you want to reach height.
2. Prune the sides, not the top, in years one and two.The aim is to force branching low down. Reduce side shoots by a third to a half in the winter after planting, and again the following winter, while letting the height creep up slowly.
3. Establish the batter immediately.Cut the sides so the hedge is wider at the base than at the top — a slope of roughly 10 to 25 degrees in from vertical on each side. Light then reaches the bottom of the hedge for its whole life. This is the single most important thing in the guide.
4. Set a string line for every cut.Canes at each end with a taut line, moved as the hedge grows. A hedge shaped by eye in its formative years follows the ground rather than the horizon and never quite recovers.
5. Bring the height up in stages.Let the leaders extend, then reduce them by about a third each winter until the hedge is 150mm or so below the intended final height, at which point start cutting the top level and let the sides fill in.
6. Cut deciduous hedges in winter while young.Formative pruning of deciduous hedging is a dormant-season job, roughly November to February, which is also outside the main nesting season. Check for nests anyway.
7. Cut evergreens in spring or late summer.Yew, laurel, privet and holly respond better to formative cuts in the growing season. Late spring and late summer are the windows.
8. Keep the base weed-free and mulched throughout.A young hedge competing with grass at its base grows perhaps half as fast. Mulch a strip 600mm wide, kept clear of the stems, for the first three years at least.
9. Move to maintenance cutting once the shape is set.From about year four, the hedge needs its species' normal routine — one cut a year for hornbeam and yew, two or three for privet and conifers — with the batter maintained every time.

Tips

• The hardest part is emotional. Cutting a hedge you paid for back by a third feels like vandalism and is the reason most people skip it.
• A hedge cut with a batter sheds snow rather than being splayed open by it, which matters on tall hedges in exposed places.
• Measure the batter with a simple wooden frame cut to the profile you want. It makes a self-taught cut look professional very quickly.

Common mistakes

• Letting the hedge run up to full height in three years — It produces a tall thin screen on bare legs, and once the base wood has no buds it will never fill in.
• Cutting the sides vertically — The top then shades the bottom, and the bottom thins and dies out. This is the mechanism behind almost every bare-based hedge.
• Topping a conifer hedge before it reaches height — Conifers put on height from a leader. Cutting it early stops upward growth, and unlike broadleaves they will not readily throw a new leader.
• Leaving grass growing up to the stems — Grass out-competes young hedging for water and nutrients and can halve the growth rate. Mulch the strip.

If it doesn't work

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