How to plant a tree

Enhance your outdoor space, help wildlife and the environment

In these times of climate emergency most of us can do a little something to mitigate the negative impact we humans are having on the planet. Planting a tree has such a huge positive effect; even if you don’t have a massive garden you can still have a small tree in a container, provided it’s large enough. Make sure you chose a species which is appropriate to the space, if in doubt ask a member of staff in your local garden centre or nursery. This year, 2022, is the ideal time to plant a tree as part of the Queen's Green Canopy. An initiative instigated by the Queen to celebrate her Platinum Jubilee, 70 years on the throne.

Trees are one of the wonders on the natural world, they provide us with clean air, they modify the temperature when it’s baking hot, they provide food and shelter for millions of insects, birds and mammals and lastly they provide food, shelter and warmth for humankind. They are also hugely important in preventing erosion; where forests have been denuded in the tropics there are massive problems with soil washing down into fish spawning grounds and also causing landslides resulting in loss of life and homes. One single Common Oak (Quercus rober) can be home to approximately 284 species of insects plus birds, mammals and fungi. Not many of us can accommodate the large trees found in a native woodland but there are masses of small trees suitable for the average garden; some of the best are the ornamental crab apples and rowans as you get the flowers in spring and fruit and glorious leaf colour in autumn.

Planting a tree is easy but not quite as straightforward as just bunging it in a hole and hoping for the best; if you follow a few guidelines then there is no reason why your tree shouldn’t flourish. Trees from the garden centre or nursery come either in a container with compost or ‘bare root’ which means they have no compost around the roots and are wrapped in either sacking or a plastic bag. Container trees can be planted any time of the year provided the ground conditions are suitable, however bare root can only be planted when the trees are dormant from about October to March.

Keep the tree well watered for the first two years until they have established a good root system. If you are gardening on sandy, free draining soils add some organic matter to the planting hole; such as home-made compost, bagged compost or well-rotted farmyard manure. If you are planning on planting trees into a clay soil chose your species carefully as not many can cope with drying out in summer and being permanently cold and wet in winter. As with the sandy soil add a good amount of organic matter.

Trees which can cope with a clay soil include:

• Amelanchier lamarkii (Snowy Mespulis)
• Arbutus unedo (Strawberry Tree)
• Betula sp (Birch)
• Crataegus monogyna (Hawthorn)  -  great for the birds
• Cotoneaster pendulus  -  loved by birds
• Ilex sp (Holly)  -  another one for the birds
• Malus sylvestris ssp (Crab Apple)  -  loved by birds and insects, also makes delicious Crab Apple jelly

It was previously thought that a general purpose fertiliser sprinkled into the hole at time of planting was beneficial but advice on this has now changed, in the belief that this encourages top growth before the roots have developed sufficiently to support the crown. Wait until the tree has been in the ground for a couple of years before feeding with a general purpose fertiliser such as blood, fish and bone or chicken manure. After a couple of years feed and water the tree then mulch in autumn with at least 5cm (2”) of chipped bark, home-made compost, leaf mould or well-rotted farmyard manure. Don’t place the mulch right up to the trunk, leave about a 5cm (2”) space otherwise it just provides a nice warm damp home for insects and fungi. This will need replenishing every 3 – 4 years.

A tall tree may need staking for a few years until it has established a good enough root system to support itself, about 3 – 4 years. Use 2 x 5cm x 5cm (2” x2”) stakes and place them in the ground close to the tree at a 45 degree angle, one either side of the tree. Secure the tree to the stake with rubber ties with a buffer between the tree and the stake to prevent chafing.

Avoid pruning the tree for the first 2 – 3 years, just take out any diseased or broken branches. Pruning stimulates top growth at the expense of root formation which is vital in the early years. Once the roots have become established then the tree can be pruned.

Bare root

The roots of bare root trees must be kept moist until you have time to plant them; if they are wrapped in plastic they should be damp but open the plastic so that they don’t sweat and go rotten. If they are wrapped in sacking there is a high chance they could have dried out so as soon as you get them home open the sacking and place them in a bucket of water for a couple of hours. If you are not able to plant them straight away ‘heel’ them in; dig a hole somewhere out of the way in the garden and just pop them in until you are ready to plant.     

When you are ready to plant, spread out the roots and remove any which are damaged, dead or growing in towards the trunk. Use clean sharp secateurs to minimise any risk of infection. Dig a hole deep and wide enough to accommodate the spread-out roots. Loosen the soil in the bottom of the hole to make it easier for the roots to grow into. Place the tree in the hole so that the crown of the tree, where the trunk meets the roots, is level with the soil surface, a cane is handy here. Back-fill half-way up the hole with the soil then water to settle the soil and fill in any air pockets. Don’t be tempted to tamp it down with a spade or your heel as this could damage the roots. Fill the remainder of the hole and construct a ‘wall’ around the tree about 5cm (2”) high and 15cm (6”) away from the trunk to create a moat. Fill this with water, which will then be absorbed and not just run off.

Container grown

Prepare the hole; about twice as wide as the container and deep enough so the tree is planted at the same level as it is in the pot. Loosen the soil in the bottom of the hole. Water the tree well while it is in the container then remove the pot and tease out the roots with your fingers. As with the bare root, remove any broken or dead roots and any which are growing towards the trunk instead of outwards. Place the tree in the hole and half fill with the soil, water to settle the soil and fill in any air pockets. Fill in the rest of the hole and as with the bare root tree, make a small wall about 30cm (12”) in diameter then fill with water.