Commercial tree growers are worried that when government policy for planting millions of new trees every year eventually kicks in and is backed with finance, they won’t be able to keep up with demand. The solution may be to get thousands of people, especially perhaps school children, to start growing trees at home. If everyone grew just a few, and especially if those trees were planted locally to where the seed was collected, it could make a huge difference. We encourage volunteers, partners and supporters of WoodsfortheTrees to get planting. The easiest trees to grow from seed are the big nuts: oak, hazelnut, horse chestnut and beech. Try those first if you want rapid success. As you’ll see from the below, different sorts of tree adopt different strategies fro producing and dispersing their seed; and that makes a difference to the way in which they can be propagated. Some trees, notably willows, are dead easy to propagate by ‘striking.’
Trees need a means of dispersing their seed so that they don’t all fall beneath their parent, where they are less likely to survive. Trees use wind, water, birds and mammals to transport their seeds to an appropriate distance. Some birds swallow fruit and excrete the seeds elsewhere in their territory; some birds and mammals hoard nuts underground and forget where they are. Tree planters rate seeds by what they call ‘dormancy’: that means that many need special treatment before they will germinate. In the case of berries (fleshy fruits) – from hawthorn, rowan, whitebeam, cherry and so on – a hard seed case is coated with substances that inhibit germination until they have been removed by the action of acids in a bird’s stomach. See ‘Growing trees from seed’ below.
Many trees can be propagated for very little cost – it’s just a question of budget and patience (or impatience) and the potential satisfaction of growing from seed or from a cutting. Cut a rod off a willow tree in late winter and stick it in the ground and the chances are it’ll grow; plant a hundred acorns in autumn and most of them will become oak trees. The following are some simple tips for collecting and sowing seeds, taking cuttings and other methods for growing trees without buying them. But it is important to remember two things: one is to ask permission if you want to collect seed or take a cutting from a tree on private land. The other is to ensure that you use seed from a tree that is healthy and grows as close to its final planting spot as possible. Planting Scots pine seeds from Norfolk on a Scottish hillside or vice versa is a no-no. Local is best.
Autumn is the time for collecting and sowing seeds. Ripe nuts are dull green or brown and can be collected from the ground as they fall, although the first nuts shed by a tree are often not the best specimens. Collect them in a paper or cloth bag and label them if you are not confident about telling them apart. It’s worth keeping a seed collecting diary so that you can look back and see which nuts and seeds from which trees have been the most successful. Winged seeds can be picked straight from the tree as soon as they are brown. Berries and other fleshy fruits are ripe when they are at their richest colour, sometimes deep into winter. Collect cones from the tree or ground when they have turned brown, late on in autumn. Keep them dry in a paper bag until the seeds have dropped out of the cone.
The Tree Council maintains a very useful website that organises, and offers advice on, seed gathering:
Growing trees from seed – mimicking nature:
The larger fleshy nuts are the easiest to propagate, because they carry ample reserves of the energy that a new seedling needs to establish itself. Straight from picking, drop the nuts into a bowl or bucket of water and fish out and discard those that float. Bury the good nuts in fresh, free-draining moist compost or soil in pots or directly in the ground, about an inch and a half below the surface, and let nature do the rest. I reckon on about a 70% success rate: so if you want 70 trees, plant 100 acorns. Pick the best and freshest nuts and don’t leave them around the house in a paper bag to get dry – just go right ahead and plant them as soon as you can after collecting, two or three to a pot. With beech nuts, many of the shiny brown seed casings do not contain an active kernel, but with practice you’ll find you can tell full from empty by gently squeezing them. The fat ones have nuts in. Some tree growers stratify beech and hazel nuts (see below); but I’ve never found it necessary.
The seeds of field maple and hornbeam don’t need to be separated from their ‘wings’, but they do require stratification to mimic the natural conditions of a winter – and in some cases two winters. The stratification medium is simple: one volume of peat-free potting compost to one of sand or bark chippings or grit, to one volume of seeds. Mix well. Put the mix into a well-drained pot, cover and keep in a cool shady spot. Come the spring, you can tip the mixture out and see if any seeds are sprouting green. If they are, take them out and sow in pots with compost and watch them grow. Put the rest of the mixture back in its pot and have another look in a week or so. Be patient: some seeds will take two winters to germinate.
The fruits of rowan, hawthorn, crab apple and holly also require stratification; but they must first have their flesh removed. Put them in a sieve and rub them under water, or mash them with a potato masher then rinse, and discard any seeds that float in water. The seeds from fleshy fruits all need to be stratified to mimic not just the effects of winter but also the conditions inside a bird’s stomach.
The seeds of alder and Scots pine cones should be sown directly into moist compost in pots, two or three at a time. Keep the pots in a cool, shady spot and see what emerges in spring. I find it helps to keep cone seeds in a plastic bag in the fridge with a little mositure for three weeks – they quite often germinate there, and you can then plant them out knowing they’re live.
Cuttings and layering: DIY propagation
Fruit trees, hollies and other so-called ornamentals are expensive to buy. But even in a small woodland it is worth having both. A cheap alternative to purchase is to learn the arts of taking hardwood cuttings and of grafting. There is any amount of advice on how to propagate holly trees from cuttings – and some of it is contradictory. My advice would be to try a few methods and see which is the most successful for you; but, basically, the technique is as follows: towards the end of the year select a healthy stem from the current year’s growth. Cut it from the tree at right angles with secateurs, then diagonally at the top end so that you have a stem between nine inches and one foot (20 and 30cms) long, and leave a healthy bud at the top. Dip the bottom end in hormone rooting powder or gel and insert into a pot of compost with a layer of sand at the base and make sure that about 2/3 of the stem, with no leaves, lies below the surface. Keep the compost moist and frost free. The buds should sprout the following spring. Give the cutting a year in its pot before planting out; if two or more shoots come up in a pot, separate them after their first growing season and pot individually. Willows (Grey, White, Crack, Goat etc) are the easiest trees to propagate. Cut rods off a willow, as for holly; there is no need to use a rooting hormone. Just place them in a pot or directly in the ground, firming down the soil around them and making sure they are well-watered in their first year. In spring they will produce shoots, tentatively at first and then vigorously. I tend to grow them in small tube shelters attached to a cane for the first year, to keep rabbits and rodents away while they take root. Plant densely, then transplant excess shoots elsewhere.
Grafting: an age-old skill
The grafting of a shoot (scion) of one species of tree onto the rootstock of another seems to have been going on for thousands of years. The armies of Alexander the Great are said to have domesticated the apple by bring grafts back from the Tien Shan mountains of Kazakhstan, where it grows wild in abundant variety. You can buy rootstock from a good local nursery, or you can grow it from the pips of a locally grown crab apple – the best rootstock for the domesticated varieties. Take a healthy cutting with strong buds, in late autumn or in a frost-free part of winter, from the tree you wish to ‘copy’ and make sure that the lowest part of its stem is of the same diameter as the rootstock that you will graft it to – roughly a quarter of an inch or 6mm across. Using a very sharp knife make fresh, upward slanting cuts and a ‘tongue’ on both rootstock and scion where they join, bind with a natural twine or floral tape and cover with wax to protect against disease. Pot the graft up and keep cool and moist for a few weeks. There is plenty of more detailed advice in many books and online on the details and techniques of successful grafting.
One of life’s pleasures is the gift of giving, and there’s a lot to be said for being able to make a present of trees that you have raised from seed or cutting, for friends and relations or a local school. But if a few of you get together and get organised, you’ll be able to propagate enough trees to start a new wood.