Hazel

Light and exposure

Hazel grows equally well in full sun or partial shade, which explains why you find it naturally at the edge of woodland as much as out in the open in hedgerows. It copes very well with the light shade of a neighbouring tree or a mixed hedge.

For a good crop of nuts, though, aim for a spot that gets several hours of sun a day. In dense shade the shrub grows and greens up without any trouble, but it flowers and fruits noticeably less. A hedge corner that catches the morning sun always produces more hazelnuts than a shaded back corner. In a hot dry climate the reverse holds: afternoon shade spares the foliage needless stress.

Watering

Once well established, hazel copes perfectly well on normal rainfall in a temperate climate and needs no watering at all. It is a hardy shrub with an extensive root system that draws deep into the soil.

The first two years after planting are really the only time you need to watch the watering, while the roots are spreading out. After that, a can of water is only worth giving during a prolonged drought in the hot season, right when the nuts are filling out: a lack of water at that stage gives smaller, less well-filled nuts. Under a long dry summer, that watering stops being an exception and becomes the rule.

Soil and repotting

Hazel is not fussy and copes with most garden soils, including heavy clay or chalky ground. An ordinary soil, neither too poor nor too rich, suits it just fine.

The one thing it really cannot stand is waterlogging around the roots. On ground that holds water through the cold season, it is better to plant on a slight mound or improve the drainage at planting time. Outside of that, moist, well-drained soil is all it needs to thrive.

Temperature and humidity

This is one of the hardiest shrubs you can grow: USDA zones 4 to 8. Hazel shrugs off severe frost, well below minus twenty degrees, and holds down to around minus thirty while dormant.

The point to watch is its very early flowering: the male catkins open at the tail end of winter, and the tiny female flowers follow shortly after, right in the middle of frost season. A severe late cold snap during that window, below about ten degrees under zero, can damage the flowers and reduce that year’s harvest, but the shrub itself is never harmed. It is the flowering that is vulnerable, not the wood. At the other end, it takes around thirty degrees in summer as long as the soil stays moist: it is drought that penalises it, not heat alone.

Pruning and upkeep

Hazel is traditionally grown as a stool, that is, a clump of several trunks coming from the base rather than a single-stemmed tree. To keep the shrub productive, renew it every winter by cutting one or two of the oldest branches back to the base each year, making room for young wood that is more vigorous and more productive.

Hazel also throws up plenty of suckers, shoots that appear on their own from the roots around the base. If you do not want it spreading and taking over the surrounding hedge, remove them as they appear. On the other hand, these same suckers are exactly what makes the shrub so easy to multiply, see below.

Pests and diseases

The signature pest of hazel is the hazelnut weevil, Curculio nucum, whose female lays an egg inside the young nut in spring. Its white grub develops inside by eating the kernel, and the nut falls to the ground pierced and empty well before harvest time. Systematically picking up and destroying any nuts that drop early breaks a good part of this pest’s cycle.

Squirrels and field mice are often the first to enjoy the harvest, sometimes before the gardener even gets a look in. Another typical problem is the hazel gall mite, which causes buds to swell into abnormally round, fat shapes over winter, easy to spot on the twigs by eye: simply spot them and remove them at pruning time to keep the damage in check, without it ever threatening the overall health of the shrub.

Propagation

The simplest and most reliable method in the garden is to lift an already-rooted sucker from the base of the plant. Dig it up with as much root as possible in autumn or winter, while it is dormant, and replant it straight into its final spot: it nearly always takes without any trouble.

Layering also works very well: bend a low, flexible branch down into the soil, hold it in place with a stone or a peg, and it develops its own roots within a year or two before being cut free from the parent plant. Growing from seed is possible but best left to patient hobbyists: young seedlings take several years before they start fruiting and do not always produce nuts identical to the parent plant.

Month-by-month care calendar

Green Hub tips

• Always plant two different varieties near each other: wind-borne cross-pollination noticeably improves the harvest compared with a single shrub on its own.
• Pick up and destroy any nuts that fall pierced before their time, it is the single most effective move against the hazelnut weevil.
• Do not let suckers take over the whole hedge, unless that is exactly what you want, since they are also the easiest way to multiply the shrub for free.
• Renew the stool every winter by cutting one or two old branches back to the base: young wood always produces more nuts than old wood.