|The Secret Garden's new hazelnut tree|
Nuts are a tricky prospect for the urban garden, however. You will need space, ideally for more than one tree, since nut trees are not, on the whole, self-fertile. You will also need an anti-squirrel plan, but beyond that, nut trees need little in the way of maintenance and looking after.
The four main species grown in the UK - and mostly in the south of the UK - are hazelnuts (cobnuts), walnuts, sweet chestnuts and almonds.
Hazelnut trees grow well in southern England – traditionally they were grown on a commercial scale in Kent among the hops. This is why the hazels mostly grown in the UK are a variety of Kentish cob, where they will thrive in any type of soil, except that which is waterlogged.
They may not be at their best in a small urban garden, but you can decide if it's worth giving hazelnuts a go.
To pollinate successfully, ie, to get a good crop of nuts, you need at least two different types of hazel tree. Hazels are self-sterile: they may have both male and female flowers on each tree, but flowers from the same tree won't pollinate each other. They need a tree nearby of a different variety of hazelnut. Before you decide to buy 2-3 trees, check your neighbourhood. If there are hazel trees in the next garden, or the next after that, the chances are that it will wind-pollinate your tree quite satisfactorily.
To plant a nut tree, choose a site either in the sun, or brightly-lit part-shade, where the soil will drain well. Dig a hole that will fit your roots and base comfortably, water well, drop your sapling in and replace the soil, firming the surface. These days, experts often recommend that you don't add any manure or fertiliser to the planting hole or the soil: you want the tree to send down strong roots in search of nourishment, not loll around in the luxury of its original planting hollow.
A stake is always a good idea even if it’s only temporary until the tree sends down strong roots and establishes itself. Use a soft tie to tether your tree to the stake, so that wire or twine doesn’t cut into the bark of the tree as it grows – an ideal soft tie is a leg cut away from an old pair of tights!
Clear the area underneath the tree – the drip canopy – of any grass, or weeds and mulch it thoroughly with organic matter and/or composted bark. This helps to suppress weeds which might compete with the tree for nutrients, and will also help to retain moisture.
Hazelnuts are picked when they are still fresh and green, from August through to October. They are usually eaten straightaway, when the nut is still relatively green and juicy. If you leave the nut until the shell goes brown, the nut will be drier in texture, but fuller in flavour. Hazelnuts store well up to Christmas if you keep them somewhere cool and dry.
The squirrel problem
Squirrels are probably most closely identified with hazelnuts but they are a problem for all nut growers, since they will eat or make away with as many nuts as possible. In a setting with plenty of space, you can minimise the problem by planting your nut tree away from woodland, leaving about 100m between the nuts and other trees. That's not possible in the Secret Garden and unlikely to be a viable solution in most urban gardens.
What is possible is to take a sheet of pliable aluminium 1m in width and tack it around the tree at about eye level here just as the nuts are forming. This should stop squirrels from climbing the tree although you will need to make sure they can’t jump from another tree to your hazel. Remove the aluminium after you’ve harvested.
Nut weevils can also be a problem. You’ll know if you have nut weevils because you’ll have nuts with a tiny, perfect circular hole bored into each one – and the nut will have been eaten.
Nut weevils can be controlled or eliminated if you cultivate the ground underneath the tree. Digging, raking, weeding, will disturb the weevils. Alternatively if you have chickens you can let them loose under the tree and their scratching will have the same effect – Bunny Guinness recommends this as an anti-weevil measure.
Even if the squirrels do bag most of your harvest a hazel tree is still worth growing. They are quick-growing and pretty with the catkins emerging in early spring. Their straight branches are traditionally used as canes and plant support – cut them down in winter and store somewhere cool and dry. They can also be trained into arches and other decorative forms and are often used as hedging.
But if you think your garden isn’t suitable for a hazelnut tree – too small, too many trees, too many squirrels – you can still enjoy fresh-picked cobnuts in season as they are one of the easiest foods to find when foraging. Get out into your local commons, hedgerows and woodlands, and look for hazelnut trees.
For me, these are the best nuts for foraging. We lived near sweet chestnut woods when I was a child and I can well remember the excitement of the sweet chestnut season, picking over the windfalls.
If you don't live near wild sweet chestnuts, a bought sweet chestnut sapling should produce nuts for you in 2-3 years. There’s nothing to say you can’t grow a nut tree from seed, so long as you bear in mind that: 1) you can’t guarantee that it will grow true, 2) you can’t guarantee it will be a healthy specimen, and 3) it will take years (10 for a walnut, up to 20 for a sweet chestnut) before it bears nuts. Make sure you still want to be living in the same house by then or else you will only bequeath a nut tree to the next owners.
Take care when buying a sweet chestnut tree in the UK. Recently a fungal disease affecting sweet chestnuts has ravaged trees in France and isolated cases have been reported in the UK. Make sure you buy your tree from a reputable supplier and that the tree is guaranteed fungus free. Some suppliers, eg Mammoth, have actually suspended supplies of sweet chestnuts until they can guarantee that their stock is free of the fungus.
Having found your reputable supplier, choose a self-fertile variety, unless you live in a stately home with its own parklands and have the space to plant more than one tree. Varieties such as Regal and Marigoule are both self-fertile, not too huge (Regal will grow to 15 feet in 10 years) and will give you nuts in 2-4 years.
Once you’ve overcome these hurdles, chosen your variety and the right location in your garden, the sweet chestnut will give you few problems. Squirrels like them – of course – and the same prevention methods with hazelnuts will work with chestnuts.
There is something very aspirational about a walnut tree. I once tried to persuade my husband we should move out of London to a house in Hampshire – solely because it had a mature walnut tree in the garden. I actually don’t remember anything about the house.
The mature trees are beautiful in a stately, elegant way – a lovely, spreading shape with intensely green, oval leaves. They are slow to grow and establish - and in the wild, slow to fruit (about 10-15 years) - so there is something of permanence and history about them.
And then of course they produce walnuts. And the difference between the walnuts you buy the shops, whether dried up and brown-shelled or ready-shelled, and the nuts that fall off your tree, is a revelation. Wet walnuts, with the shell still soft and undeveloped, can be pickled, but once the green husks fall from the tree and split to reveal the shell, the nut inside is moist and rich and creamy.
So, you want to plant a walnut tree? You’ll need two of them, at least. Walnuts tend not to be very self-fertile and will crop much better if there is another walnut tree of a different variety nearby (and of course, you’ll get more walnuts).
Chose a named cultivar, and plant as for other nut trees. Keep well watered as the tree establishes itself and gradually reduce this as it grows – walnut tree roots can rot. When the tree crops, wear gloves – the outer husks will stain your hands indelibly. I speak from experience having spent a week in Spain with black hands after I filled my pockets with wet walnuts – I think I thought I was going to pickle them back at the villa.
Walnut trees have another interesting characteristic: their roots exude a chemical which deters other plants from growing near it – so, easy weeding. I also wonder if this has anything to do with the traditional saying that you don’t get flies under a walnut tree. If the chemical deters more than plants as it were. Certainly walnut trees are not much affected by pests. There is such a thing as walnut blight, a bacterial disease which makes black spots develop on the leaves and can also affect the crop. Apart from that, it’s the old enemy, squirrels, which you need to guard against.
Almonds like warm dry summers and frost-free winters to do their best, so they are a tree that does best in the south-east – like walnuts, in fact. In London the clay soil and consequent poor drainage is likely to be your biggest problem.
Almonds come from the same plant family as peaches and nectarines – think of the kernel of a peach/nectarine with that distinctive bitter almond taste. So the growing conditions are very similar.
If you want to grow an almond tree, you’ll need deep, free draining soil. Dig in lots of organic matter prior to planting and if you have a slope in your garden or allotment, plant near the top, not at the bottom. You also want somewhere in full sun or as close to it as possible. Buy a sapling, either as a bare root plant or in a pot, rather than trying to grow from seed, and you should have nuts in the second or third year.
The best way to harvest almonds is to lay a big sheet underneath the tree and then shake the branches hard to make the fruit fall out and on to the sheet. Let them dry for a few days before you start to eat them.
As they are related to peaches , they attract the same pests: in this case, leaf curl is the most likely problem you’ll get. Keeping the plants dry in late winter and early spring is one way to help prevent this fungal disease; using a copper fungicide in January/February is also effective.