Great to forage but if you want to grow your own hazelnuts, David Patch offers this simple-to-follow guide.
What are hazelnuts?
Hazel is the name given to any member of the Corylus family. There are 18 different species, which are spread across much of the Northern Hemisphere. The nuts from all of these are edible, but we will be concerning ourselves here with just two – Corylus avellana (cobnut), the only true native British nut, and Corylus maxima (filbert) which was introduced to the UK from Northern Europe more than 2000 years ago. Although there is a slight difference in their shape, the terms cobnut and filbert are generally interchangeable, and both come under the catch-all name of ‘hazel’.
Buying and planting hazelnut trees in winter
Hazels will grow well in a wide range of soils – for preference they enjoy a relatively free-draining site in full sun, but will tolerate some shade. Very heavy clay soils are best avoided, unless you can incorporate lots of washed sand and grit before planting. They are happy in a slightly exposed position, so can be used as a windbreak, but remember they are wind-pollinated and best planted together in clumps rather than single rows, otherwise yields will suffer.
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A mature nut tree will have a spread of 2-2.5m (6½-8ft), so plant at about 4m (13ft) spacing from each other. Hazels are normally sold as bare root plants in the winter months – you may have to search online to find a specialist nursery. Dig a good-sized hole – around 50cm (20in) in each direction will be ample – and incorporate some leaf mould or home-made compost to improve soil structure. No need to add any fertiliser – nut trees have reasonably low feed requirements – but it is a good idea to use one of the mycorrhizal products such as Rootgrow. Hazels have a strong symbiotic relationship with several soil fungi, and encouraging the proliferation of these will reap rewards in future years. For this reason, it’s also an excellent idea to mulch every winter with compost, leaf mould or well-rotted manure, which add organic matter and help increase the diversity and population of these soil micro-organisms. Just keep a ‘collar’ clear around the base of the plant so the bark on the stems doesn’t rot.
How to plant hazelnuts trees in spring
All hazelnut trees are monoecious – they bear male flowers (the long yellow catkins) and female flowers (small and inconspicuous, with red feathery stigmas) on the same tree. Hazels are wind-pollinated so the female flowers aren’t designed to attract bees, but to catch any passing pollen grains blown from neighbouring male catkins. For this reason, plant them reasonably close together, and plant in blocks rather than rows.
Hazels are not reliably self-fertile, so to ensure good crops it is best to plant two bushes of different varieties (although any common hazel in a nearby hedge will work very well for pollination). Any two will normally work for pollination purposes, and cobnuts will pollinate filberts and vice versa.
Hazels are slightly peculiar, in that although flowering and pollination take place in spring, fertilisation only takes place later in mid-summer. The initial transfer of pollen stimulates the development of the shell of the nut, but the nut itself is only produced once the male and female cells fuse together a couple of months later. If for any reason the fertilisation fails to take place, the result will be ‘blanks’ – a nut with a shell but no edible kernel inside. This can be an issue, especially if the summer weather is cool and wet. The good news is that it isn’t a sign of disease and if the weather is better the following year yields should return to normal.
Pruning hazelnut trees in summer
Nut trees don’t really need a huge amount of pruning – they naturally grow as large multi-stemmed shrubs. To keep them under control after they have been planted for three years you can start to take some of the very oldest stems back to ground level, a process called coppicing. This has the benefit of encouraging new productive stems to grow, it keeps the centre of the plant clear for better air circulation and pollination, and gives you the gardener a very welcome supply of hazel rods to use as supports around the garden! You normally do this in late winter.
However, there is a specific summer pruning task called ‘brutting’ which is worth getting to grips with. It’s done in August, and you can think of it in the same way as summer pruning of apples and pears – it contains growth and instead helps the plant put its energy into fruit production the following year. Simply snap any of this year’s strong lateral growths in half, leaving around six buds. You don’t remove the broken part of the stem, but leave it hanging there in place, and you can prune it off when you do your late winter pruning.
Harvesting hazelnuts in autumn
If I asked you to imagine a hazelnut, I can guarantee you would think of a brown, hard nut – possibly in a bowl at Christmas. In fact, hazels may be picked early when still not quite fully ripe – hazels eaten ‘green’, fresh off the tree at the end of August, are a true delight. Sweet, almost milky in flavour, they are delicious and almost unrecognisable from the dried nuts imported from Turkey and Italy later in the year.
Otherwise, hazels will ripen through September and October, when the husks start to turn a yellow-brown and the nuts loosen and fall to the ground. Most cobnuts will ‘free fall’ and you’ll start to notice them on the ground under the tree after periods of strong winds. Most filberts, however, remain tightly enclosed within the husk even when fully ripe, so pick the clusters from the tree and take into the kitchen to de-husk.
The only major problem to worry about if you want to grow hazelnuts is grey squirrels. Just as you start to look at the lovely green fruit in mid-August, deciding when to start picking, squirrels will be doing exactly the same thing and beat you to it. If they are a problem in your garden or allotment, there is very little you can do, other than be prepared to share your harvest.
If you are growing the trees as single stems, you can put tall aluminium tubes on the trunk to keep them away from the nuts, but this is rarely practical for the home gardener. Siting trees in the open and away from other trees helps – squirrels will hesitate to cross open ground for fear of being too exposed. If you own a dog, all the better!
