Start With the Tree You Will Have in Twenty Years

It is easy to fall for a neat little sapling in a two-litre pot, imagining it will stay that size. It will not. The single most useful habit when choosing a tree for a small garden is to look past the plant in front of you and picture the one you will be living with in two decades.

Check the eventual height and spread on the label, then treat those numbers as a best-case scenario. Nursery labels are frequently optimistic, and a tree planted in good soil with no competition often exceeds its stated dimensions. In a compact plot, a realistic target is a tree that finishes somewhere between four and eight metres, with a spread you can still walk around.

Useful small trees for British gardens include:

• Amelanchier lamarckii – frothy white spring blossom, berries and orange-red autumn colour, usually topping out around six metres.
• Acer griseum – the paperbark maple, slow-growing with peeling cinnamon bark and reliable autumn colour.
• Sorbus aria 'Lutescens' – a compact whitebeam with silver foliage and orange berries, tolerant of chalk.
• Prunus 'Amanogawa' – a narrow, upright ornamental cherry ideal for a tight corner or beside a path.
• Malus cultivars such as 'Evereste' – blossom, fruit for the birds and a naturally modest habit.

The Space Below Ground Matters as Much as the Space Above

Roots are the part most gardeners forget until paving lifts or a drain blocks. Most tree roots spread far wider than the canopy, and they are concentrated in the top 60 cm of soil, which is exactly where your services, footings and flower beds live.

As a working rule, keep a tree at least half its eventual spread away from a building, and further still from drains, soakaways and conservatory bases. If planting close to a boundary, choose something slow-growing, or use a fruit tree on a restricting rootstock. For apples, M27 and M9 keep trees genuinely small; M26 suits a slightly larger space. Plums and gages on Pixy stay manageable, and pears on quince C are compact enough for a modest lawn.

Before you dig, check whether the tree will fall under a Tree Preservation Order or sit within a conservation area. Your local authority planning department can confirm this quickly, and it is far easier to ask first than to explain later.

Read Your Soil Before You Read the Catalogue

British gardens serve up everything from heavy Wealden clay to thin chalk over flint and light, hungry sand. Knowing which you have saves a great deal of disappointment.

• Clay holds water and nutrients but drains slowly. Acer campestre, Crataegus and many Sorbus cope well once established.
• Chalk and limestone are alkaline and dry out fast. Choose Sorbus aria, Taxus baccata, Ilex aquifolium and Cercis siliquastrum.
• Sandy or gravelly soil drains freely and dries in summer. Betula, Pinus and many flowering cherries settle in happily.
• Waterlogged ground is the hardest test. Improve drainage, or plant willows, alders and amelanchier that tolerate wet feet.

Dig a spade-depth hole and fill it with water. If it drains within an hour or two, you have free-draining soil. If it stands for a day, you have a drainage problem to solve before planting anything.

Match the Tree to the Light You Actually Have

Be honest about aspect. A south-facing border against a warm wall gives you far more scope than a shaded north corner beneath next door's leylandii. Most flowering trees want at least half a day of direct sun; foliage and bark trees are more forgiving.

For genuinely shady spots, consider Taxus baccata (yew), Ilex aquifolium (holly), Sorbus aucuparia (rowan) or Corylus avellana 'Contorta'. All will grow steadily in light shade, if a little more slowly than in full sun. Remember that a tree planted where it is shaded on the south side will lean, and one crammed against a fence will grow lopsided as it reaches for light.

Decide What Job the Tree Needs to Do

A small garden tree has to earn its place, so be clear about its purpose. Screening, blossom, autumn colour, fruit, wildlife value or simply a strong architectural shape – ideally two or three of these at once.

If you want a larger species in a small space, training offers a way in. Pleached trees create a raised screen, multi-stem specimens give structure without bulk, and hazel or willow can be coppiced on a short cycle to keep them permanently juvenile. Pollarding works too, though it means annual pruning for the life of the tree. Columnar and fastigiate forms – Pyrus calleryana 'Chanticleer', Quercus robur 'Fastigiata' – squeeze height into a narrow footprint.

Buy Well, Plant Properly, and Water for Three Years

Bare-root trees, available from late autumn to early spring, establish faster and cost less, but must go in while dormant. Container-grown trees can be planted almost any time, provided you water diligently through the first summer.

Plant into a square hole roughly three times the width of the rootball but no deeper than the tree's original soil mark. Firm gently, stake only if the site is exposed, and mulch to a depth of 7–8 cm, keeping it clear of the trunk. Then water thoroughly once a week for the first two growing seasons and during any dry spell in the third. After that, most trees are on their own – and you can start enjoying the shade.