Pruning Hazelnuts: Coppicing, Suckers and Keeping the Bush Open

It is a bush that renews itself from the base

A hazel is not built like an apple. It has no permanent trunk and no long-term framework of scaffold branches. Instead it throws up new stems from a crown at ground level, each stem grows, crops for a decade or so, becomes congested and unproductive, and is replaced by a younger one. Pruning a hazel means managing that turnover rather than shaping a canopy, which is why fruit-tree pruning advice applied to a hazel produces such poor results.

This habit is the reason hazel has been coppiced for thousands of years. Cut a stem to the ground and the crown responds by sending up several vigorous new ones. Cut the whole stool to the ground and you get a complete new bush within a few years. The plant is designed to be cut, and it does not resent it the way a stone fruit does.

For nuts specifically, you want a permanent bush of six to eight well-spaced stems, with the oldest replaced gradually so the bush always carries a range of ages. Nuts form on one-year-old wood, so a bush entirely of old, congested stems crops badly and a bush entirely of new growth has not yet made flower buds. A spread of ages keeps production steady from year to year.

When to cut, and the one date that matters

The main pruning is done in the dormant season, but the timing within it is not free. Pruning before or during flowering removes the catkins, and the catkins are the pollen supply for your own bush and for every other hazel within range. Cut a bush hard in early winter and you have thrown away that season's pollination as well as your prunings.

So wait until the catkins have finished shedding and gone brown and limp, which is normally late winter, and do the structural pruning then, before the leaves break. You still get the benefit of working on bare wood and you have not sacrificed the crop. If a stem must come out earlier for safety, cut it and lay the branches on the ground under the bush so the catkins can still shed where they lie.

Summer work is different. In midsummer, once the nuts have set and are visibly swelling, the traditional practice is to break rather than cut the strong side shoots, snapping them part way and leaving them hanging by a strip of bark rather than removing them. The half-broken shoot stops extending, light reaches the developing nuts, and flower buds form on the remaining base for next season. It looks brutal and it works. Cut the hanging pieces off cleanly at the winter pruning.

Avoid pruning hazel in spring as the sap rises and the leaves expand. Cuts made then bleed, heal slowly and invite dieback, and you lose the developing crop into the bargain.

Where the fungal canker disease of hazel occurs, prune in dry weather only, cut well below any sunken dead patch of bark, and disinfect the saw or pruners between cuts. Burn diseased prunings rather than shredding them.

Suckers: the job that never ends

A hazel produces suckers from the base every year, and if you leave them the bush becomes an impenetrable thicket of thin stems that shade each other, crop lightly and make harvesting impossible. Removing suckers is the single most important routine job, and it is easiest done more often than feels necessary.

Go round the base twice a year, once in late winter and once in midsummer. Do not cut suckers off at ground level with pruners, because a cut stub responds by producing three shoots where there was one. Instead pull or tear them away from the crown while they are soft and green in summer, ripping them off at the point of origin. That removes the dormant buds at the base and the sucker does not return in the same place.

Keep the ones you want. Each year one or two well-placed, vigorous suckers should be retained deliberately to replace the oldest stems you are cutting out. Choose them for position, spaced around the crown, not for size, and mark them so you do not remove them by reflex on the next pass.

1. Start with the dead and the damaged In late winter, after the catkins have finished, take out anything dead, broken, diseased or rubbing. This is uncontroversial work that immediately makes the rest of the bush easier to read.
2. Take out one or two of the oldest stems Choose the thickest, grayest, most congested stems and cut them right down to the crown, flush with the ground, with a saw. On a mature bush doing this every year gives a rolling replacement cycle of roughly eight to ten years per stem.
3. Open the middle Remove branches growing into the center of the bush and any that cross. You want light and air reaching the inside, because shaded interior wood makes no flower buds and holds damp. A bush you can see through is a bush that crops.
4. Shorten strong side shoots Cut vigorous one-year side shoots back to about four to six buds. This converts extension growth into short fruiting spurs. Leave the shorter, twiggy growth alone entirely, since that is where most of the female flowers will be.
5. Deal with the suckers Clear the base completely except for the one or two you have chosen as replacement stems. Tear rather than cut where you can. Mark the keepers with a tie so the next person round the bush leaves them alone.
6. Break the side shoots in midsummer Once the nuts are swelling, snap strong side shoots part through and leave them hanging. Light gets to the nuts, extension growth stops, and flower buds set for next year. Remove the broken pieces at the following winter pruning.

Full coppicing and starting over

An old, neglected hazel that has become a thicket 20 ft (6 m) across with all its growth at head height can be cut to the ground entirely. Take every stem down to a stool 4-6 in (10-15 cm) above soil level in late winter. The stool will send up a forest of new shoots the following season, and from those you select six to eight over the next two years and remove the rest. You lose three to four years of nuts and you get a manageable, productive bush at the end of it.

This is worth doing on a bush you cannot harvest from and cannot see into. It is not worth doing on a bush that merely needs thinning, because staged renewal, taking one or two old stems a year, keeps you in nuts throughout. Choose full coppicing only when the bush is genuinely beyond gradual repair, and protect the regrowth, since fresh coppice shoots are exactly what deer and rabbits want.

Keep a simple record of what you cut and when: which stems came out each winter, how many suckers you kept, and where. A hazel stool worked on a rotation is a twenty-year project, and after five years the only way to know whether a stem is three or nine years old is because you wrote it down. That record is also what tells you whether your yields track stem age the way they should.