Planting Native Trees and Shrubs Along a Heathland Edge

Why the heathland edge matters

Heathland is not just open ground. Where the dwarf shrubs, bare earth and lichen of the open heath give way to scattered scrub and trees, you get a transition zone that holds more species than either habitat alone. This edge is where nightjars churr at dusk, where adders bask on warm south-facing patches, and where warblers nest in dense thorn. A woodland edge that curves in and out like a series of shallow bays — scalloped, in conservation language — packs far more of that valuable boundary into the same length of hedge or shelterbelt than a straight line ever could.

The trick is to create that richness without letting the trees and shrubs march outwards and smother the heath. Heather, bell heather and cross-leaved heath need open, low-nutrient, sunny conditions. Birch and willow will happily take the whole lot given half a chance. Getting the balance right is the whole craft of edge management.

Choosing natives for the edge

Stick to species that genuinely belong on acid, sandy or peaty soils, and source them from local provenance stock where you can — plants grown from seed collected nearby are better adapted and better for local invertebrate populations. Good choices include:

• Hawthorn (Crataegus monogyna) — the backbone of any edge. Dense, thorny nesting cover, spring blossom for early insects, and haws that feed redwings and fieldfares through winter.
• Silver birch and downy birch — light, airy canopies that let dappled light through, plus catkins and bark that support hundreds of invertebrate species. Be warned: they seed prolifically.
• Goat willow and grey willow — early catkins are one of the best nectar sources for queen bumblebees emerging in March. Excellent for damp hollows at the edge.
• Blackthorn — early blossom, sloes, and impenetrable nesting thickets.
• Rowan and holly — modest-sized, berry-rich, and happy on poor acid soils.
• Pedunculate oak and aspen — use sparingly and only in the deepest parts of the scallop, where they will not shade out the heath.
• Gorse — common and western gorse are heathland natives in their own right, superb for stonechats and Dartford warblers, but they need rotational cutting to stop them dominating.

Avoid the usual thugs: rhododendron, cherry laurel, snowberry and cotoneaster all escape from gardens and smother heathland. If they are already on site, remove them before planting anything else.

Designing the scallop

Think of the edge as a series of alternating curves rather than a wall. Scallops of roughly five to ten metres deep, with the woodland receding in bays and advancing in promontories, create sheltered pockets and varied light. Aim for a mix of aspects: south-facing scallops warm quickly and suit basking reptiles and invertebrates, while north-facing ones stay cooler and damper, favouring mosses and liverworts.

Keep the transition graded. Tall trees at the back, then a shrub layer of hawthorn, blackthorn and willow, then a ragged fringe of low scrub and scattered gorse, then open heath. That graduation gives wildlife somewhere to retreat to and gives you a manageable front line to keep cutting back.

Planting and establishment

Plant bare-root whips between November and March, when the ground is workable and the plants are dormant. Sixty to ninety centimetres is a good size — cheap, quick to establish and less prone to drying out than larger stock. Space shrubs around two to three metres apart; they will close up within a few years.

On heathland soils, do not enrich the planting hole. These are nutrient-poor systems and adding compost or fertiliser simply encourages rank grass, nettles and bramble that will outcompete the heather. A simple slit or notch, the roots firmed in, is enough. Use spiral guards or a small mesh cage against rabbits and deer, and keep a metre of bare, weed-free ground around each whip for the first two or three seasons.

If you are planting near a Site of Special Scientific Interest or a designated SSSI, check first — consented management is usually required before any planting on or adjacent to protected heathland.

Keeping the heath open

This is the part most people underestimate. Without management, your edge will be birch woodland within fifteen years. Plan a cutting rotation from the outset: cut a third to a half of the shrub edge on a five to seven-year cycle, working in sections rather than all at once, so there is always cover available nearby.

Pull birch and willow seedlings while they are still small enough to come up by hand — a fortnight with a weed wrench in late summer saves days of chainsaw work later. Where trees have already taken hold, cut them low and treat the stumps, or cut in late summer when regrowth is weakest. Keep a buffer of at least ten metres between the outermost scrub and any open heath you are trying to protect, and never plant into the heath itself. If grazing is an option, light conservation grazing does much of this work for you.

What you will see

Get the balance right and the rewards come quickly. Expect whitethroats and dunnocks nesting in the thorn, linnets and yellowhammers feeding on the seed heads, and brimstone and purple hairstreak butterflies using the scrub. In summer, nightjars will churr from the sheltered scallops, and the warm, bare patches at the edge will draw adders, common lizards and a wealth of solitary bees. A well-managed heathland edge is one of the busiest places in the British countryside — and it only works when someone keeps the birch in check.