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Complete guide to growing small trees for the garden
Everything you need to know about choosing and growing the right tree for your garden
By Tony Russell for Gardeners’ World Magazine
This time of year is prime tree-planting season. We all want an instant sense of scale and maturity in our gardens – but trees supposedly take ages to grow, so you may be tempted to buy in large sizes.
Research has shown, however, that trees planted when small (up to 2½ft) establish faster and more effectively than larger ones and may even overtake a larger (and more expensive) specimen planted at the same time.
Small trees have a larger root-to-foliage ratio, which means evaporation and therefore moisture needs are lower, and their ability to produce new roots is greater. They also suffer less root check immediately after planting and are less susceptible to stress in times of drought.
Buying a tree
Don’t get confused over the various names garden centres and suppliers give to different tree sizes. A whip is generally a small tree up to 3ft tall, normally produced from seed or cuttings. A maiden is a similar size, normally produced from grafting or budding. Fruit trees are often referred to as maidens. A half-standard tree has a single clear stem up to 5ft tall, topped with a head of branches, and a standard has up to 6ft 6in of clear stem, plus a head of branches.
Most garden centres sell trees that have been grown in a pot and potted on to allow for root growth. These are known as container-grown trees and can be planted at almost any time of year except when the soil is waterlogged or frozen, or during prolonged drought.
Container-grown trees tend to be more expensive than rootballed or containerised trees, which are grown in nursery beds, lifted in winter then wrapped in netting or similar material, or placed in a container for sale. Rootballed trees should be planted between late November and mid-February. Cheapest of all are bare-root trees, which are normally supplied by nurseries during the dormant season, having been grown in open ground. These should be planted as soon as possible after purchase.
How to establish a tree
After all the effort of choosing, buying and planting your tree, you’ll need to make sure it has the best chance of survival by keeping it well watered, at least through its first growing season and during very dry weather for two or three years after. A mulch of well-rotted garden compost or composted bark will retain moisture in the soil and discourage weeds. If your tree is planted in grass, it’s essential to maintain a circle of bare soil around the base of the trunk, at least 18in across.
New trees will establish quicker without competition from grass and weeds. If your tree is grafted on to a rootstock, you may find that it sends up vigorous shoots, or suckers, from beneath the graft union. Pull these off or cut them back as close to the main trunk as possible with secateurs. One final point to consider when planting or dealing with trees on your property: as the landowner you have a responsibility to maintain those trees in a safe condition, which includes regular inspections for any signs that they are unsafe. With young or small trees, the level of damage or injury that may occur if the tree, or parts of it, were to fall is limited, but a responsible attitude will prolong your tree’s life, give you peace of mind and may reward you with lower insurance.
Using tree ties
Don’t risk damaging a newly planted tree by fixing it to the stake wrongly. It is essential to use a flexible tree tie with a rubberised spacer. This will ensure the bark doesn’t get worn away and that the tree’s growth isn’t restricted as the trunk expands. Attach the tree tie to the stake, about ½in from the top, using a galvanised nail. Thread the strap through the spacer buffer, around the stem of the tree, back through the rubber spacer and around the back of the stake to finish up through the buckle. Fasten the tie securely, then knock a second nail through the end of the strap so it doesn’t slip undone. Check regularly to ensure the tie isn’t chafing the bark, and loosen it to allow the stem to expand.
Do I need a stake?
Small, single-stemmed trees, such as whips up to 3ft tall, rarely require staking, except on exposed sites. In fact it’s best not to stake, as the flexing of a tree’s stem helps encourage thickening of the trunk, making it better able to support the weight of the upper branches.
Even with half-standard and standard specimens, stakes shouldn’t extend above one-third of the tree’s total height. For most well-grown specimens a short stake that anchors the base of the trunk is ideal. This holds the rootball firmly in the ground while new roots grow out into the surrounding soil, but still allows the full height of the main stem to flex. For large standard containerised trees, use a stake angled at 45 degrees to the trunk and attached about one-third up its height. By angling the stake, you avoid driving it vertically down through the rootball, so no damage is caused.
Will trees grow in pots?
Some trees are perfectly happy in containers, which is very handy if you’re short on space. It also allows you to grow trees that are not fully hardy, such as a citrus, as you can move the pot inside over winter. You can also grow trees that are unsuited to your garden soil. In theory, most trees can be grown in containers, at least for a limited period of time. However, reality dictates that slow-growing, dwarf or compact specimens, such as varieties of Japanese maple, are the most suitable. Trees in containers do require more attention than those in open ground. You’ll need to water them regularly, as compost dries out quickly and the roots can’t grow out in search of water. Similarly, you’ll need to feed them too