Why Bare-Root Trees Suit the Cold

A bare-root tree is lifted from the field while it is dormant, with the soil shaken from its roots. That sounds austere, but it is exactly what makes these trees such good value and such willing settlers. With no leaves to support and no compost wrapped around the roots, the tree's energy goes into the one task that matters in winter: sending out new fibrous roots into cool, moist soil. In most of the UK the window runs from leaf fall in November through to late March, though the earlier part of that window is kinder. Aim to plant before Christmas if you can, particularly with evergreens, so the roots have a long, gentle run at the soil before spring asks anything of them.

Hardy evergreens are excellent candidates for a cold-climate garden, provided you choose sensibly and treat the roots with care. Yew, holly, Scots pine, juniper, box and Portugal laurel will all shrug off frost and exposure once established. The catch is that an evergreen never fully stops losing moisture through its leaves, even in January, so a dry, freezing wind can undo a badly planted tree long before spring arrives.

Check the Roots Before They Go In the Ground

Bare roots are fragile things once they are out of the soil. As soon as your tree arrives, unwrap it and look at what you have. Healthy roots are pliable, pale to mid-brown and plentiful. Brittle, blackened or snapped roots should be trimmed back cleanly with sharp secateurs to sound wood.

The golden rule is that roots must never dry out. If you cannot plant within a day or two, heel the tree in: dig a shallow trench in a spare piece of ground, lay the roots along it at an angle, cover them with soil and firm gently. A bucket of water and a damp hessian sack will hold a tree happily for a few days in a cool, shaded spot. Do not leave roots standing in water for more than a few hours, and never let them sit in a warm shed or frost-free garage, where they will dry out and break dormancy early.

Dig a Hole Wider Than You Think

Choose the site with winter drainage in mind. Most evergreens detest sitting in waterlogged soil from November to March, so if the spot holds puddles, plant on a slight mound or improve the ground first. Full sun is ideal for conifers, while yew, holly and box will tolerate a little shade.

Dig a hole two to three times the width of the root spread, but no deeper than the roots actually need. Fork the base and the sides to break up compaction, without polishing the walls smooth. Keep the nursery soil mark on the trunk at the same level as the surrounding ground; planting too deep is a common and slow-acting killer.

• If the ground is frozen solid or under snow, heel the tree in and wait rather than forcing a hole.
• Mix a little garden compost or well-rotted manure through the backfill, but never fill the hole with rich compost alone.
• Space trees according to their eventual spread, not their current size, so air can move between them.

Firming the Soil to Close Air Pockets

Build a low cone of soil in the centre of the hole and spread the roots over it, trimming any that are too long rather than curling them round. Backfill in stages, firming with your heel around the roots as you go. You are not trying to compact the ground, just to close the air pockets that let roots dry out and frost penetrate. Tug the trunk gently; if it moves, firm again.

Water thoroughly after planting, even in winter, unless the ground is frozen. A slow soak settles the soil around the roots far better than any amount of stamping. Stake only if the site is windy or the tree is tall, using a short stake and a soft tie low on the trunk, and check the tie monthly so it never bites into the bark. Finish with a mulch of bark or compost, 5–8cm deep, kept well clear of the trunk. Then check after every hard frost and re-firm any tree that has been lifted by frost heave.

Looking After Evergreens Through the Worst of the Weather

Evergreens lose water through their leaves all winter, so keep an eye on the soil during dry, cold spells. If the ground is not frozen, water deeply every few weeks. On exposed sites, a temporary windbreak of woven fabric or fleece on the windward side will reduce scorch and browning; keep the material clear of the foliage so air still moves around the tree.

Resist feeding until spring growth begins, and keep rabbits and deer at bay with guards around the trunk. A little patience goes a long way: bare-root trees often put on almost no top growth in their first year while they build roots, then romp away in the second. Planted well, in the cold and the quiet, a hardy evergreen will reward you for decades.