Why willow takes root so easily

Willow is unusual among our native trees in that a cut rod will readily strike roots if it is kept damp. Push a fresh, dormant rod into moist ground in winter and, more often than not, it will grow away by spring. This is the whole basis of living willow work: the structure you build is not a frame that plants will eventually cover, it is the plant. Within a single season a bare bundle of rods becomes a green, growing thing.

That vigour comes from the willow's natural habitat. Most useful basket and structure willows — common osier (Salix viminalis), purple willow, almond willow — evolved on riverbanks and flood meadows, where being broken by water and silted over was a routine event. Their response was to root from any buried or waterlogged stem. Coppicing simply makes use of this: cut a stool back hard in winter and it throws up a dense crop of long, straight, flexible rods the following summer.

Choosing and cutting your rods

Living structures are built from one-year-old rods, cut during the dormant season. Aim for rods between roughly 1.5 and 2.5 metres long and 8–20mm thick at the base. Thinner rods bend more easily and are ideal for weaving; thicker ones make good uprights and anchors.

• Species matter. Common osier gives long, strong rods. Purple willow (Salix purpurea, often sold as 'Black Maul') is finer and more flexible, superb for tight weaving. Almond willow is another traditional choice.
• Cut fresh. Rods should be used within a few days of cutting, or heeled into damp ground or stood in water. Dry rods are dead rods.
• Cut clean. Use sharp bypass secateurs or loppers and make a sloping cut at the base. Never leave a ragged end — it invites dieback.
• Keep the top. The growing tip is where the leader continues; don't trim it unless you are deliberately thickening the structure.

If you have your own coppice stool, cut it on a one- to three-year rotation, always in winter, and leave the cut surface clean and slightly angled so water runs off.

Building a living fence, or fedge

The simplest living structure is a woven fence, sometimes called a fedge — part fence, part hedge. Mark out a line, then push upright rods into the ground at 15–20cm spacing, sinking them 20–30cm deep. On firm or stony ground, make a hole first with a metal bar or a length of old pipe; forcing a rod into compacted soil bruises the bark and it will fail.

Once the uprights are in, weave a second set of rods diagonally between them, alternating direction to form a diamond pattern. Push the diagonal rods into the soil wherever they cross an upright, so the whole fence roots as it goes. Continue weaving to whatever height you want — 1.2 to 1.5 metres is comfortable for most gardens. Tie the top course with a soft willow tie rather than wire, which can cut into growing stems.

Domes, tunnels and screens

For a dome or tunnel, set two rows of uprights opposite each other and bend matched pairs towards one another so they cross near the top. Bind each crossing firmly with a willow tie, then weave horizontal rods around the outside to stiffen the whole thing. A tunnel is simply a dome stretched along a path; a screen is a single row of uprights with diagonals woven in. All three rely on the same principle — triangles and crossings give strength, and every point that touches damp ground becomes a new root.

Leave enough room for growth. A willow tunnel only two metres wide will close over quickly, and a dome meant for children to sit inside should start at least two metres across so the interior stays usable for a few years.

Site, soil and water

Willow wants moisture. It will grow on most soils, but it thrives on damp ground and struggles on thin, dry, sandy ground unless you are prepared to water heavily through the first two summers. A site that stays slightly damp, or a spot near a downpipe or pond edge, is ideal. Full sun gives the strongest, straightest growth.

• Plant between late November and early March, while the rods are fully dormant.
• Mulch around the base with well-rotted compost or bark to hold moisture and suppress weeds.
• Water generously in the first summer — this is the single most common reason living structures fail.
• Keep grass and weeds clear for the first year; young rods are easily out-competed.

Aftercare and getting the best from it

Once established, a living structure needs little more than annual attention. In winter, cut back the previous year's growth to tidy the shape and encourage fresh rods. You can either weave the new growth back into the structure or cut it out and keep it — those rods are your next project's material, and this is the quiet appeal of the whole craft.

Trim the sides and top in late winter to keep the form crisp, and thin any crowded uprights if the structure becomes too dense to see through. Watch for the common willow problems: rabbits and deer browsing young shoots, and aphids in early summer, which usually do little lasting harm. Give it three or four years and a living willow fence or dome will have thickened into something that reads as a permanent feature — and it will still be growing.