Some of the loveliest woodland gardening happens in the smallest of spaces. A north-facing courtyard, a paved back garden in a terrace, a balcony with more shade than sun – all can carry the quiet green texture of a wood edge, provided you choose the right plants and treat their roots with a little care. Container growing suits compact woodland species remarkably well, but it asks more of the gardener than a border does. Get the basics right and a potted hazel or hart's tongue fern will reward you for years.

Why woodland plants take to containers

Most woodland species evolved under a canopy, in shallow, humus-rich soil that stays reliably moist but never waterlogged. They are not greedy plants. Ferns, wood anemones, wild garlic, small native trees such as hazel, rowan, crab apple and holly all tolerate the sort of slow, steady growing conditions a container provides. Their roots tend to be fibrous and near the surface, which suits the shallow profile of a pot far better than the deep taproots of, say, a young oak or a field maple.

There is a second advantage: confinement keeps them small. A hazel that would make a thicket in open ground will sit politely at chest height in a 45-litre pot for years, producing catkins in February and a crop of nuts in autumn. If you want the feeling of a wood rather than a specimen, plant three or four pots of different heights and let them lean into one another.

Choosing containers and compost

Depth matters more than width. A woodland tree needs room to anchor itself, so look for a pot at least 45cm deep, and preferably 60cm for anything taller than head height. As a rough guide:

• Small trees – 40 litres minimum, with a sturdy stake and a heavy base to resist wind-rock.
• Ferns and woodland perennials – 20 to 30cm pots, deeper than they are wide.
• Ground cover such as wood anemone or wild strawberry – shallow pans are fine, but they dry out fast, so group them together.

Choose frost-proof terracotta, glazed ceramic or a well-built timber planter. Thin plastic pots heat up alarmingly in sun and crack in a hard frost. Whatever you use, it must have generous drainage holes, and it should sit on feet or bricks so water can escape freely rather than pooling underneath.

For compost, a loam-based mix such as a John Innes No. 3 is the reliable choice. It holds water and nutrients far better than a peat-free multipurpose alone, has enough weight to keep a top-heavy tree upright, and does not collapse into sludge after a wet winter. Loosen it with a handful of bark fines or leafmould to keep the structure open, and add a little grit if your site is shady and slow to drain.

Planting small trees and ferns

Plant in early autumn or late winter, when the soil is cool and roots are active. Soak the rootball thoroughly before planting, then set it so the top of the rootball sits about 2cm below the final compost surface. Work loam-based compost in around the sides in layers, firming gently with your knuckles as you go – you want no air pockets, but no concrete either.

Water in slowly until it runs from the drainage holes, then mulch the surface with 2–3cm of leafmould, bark chip or composted bracken. Keep the mulch clear of the trunk or crown. Trees will need a stake for the first two or three years; ferns will not, but they appreciate a sheltered spot out of the worst wind.

Watering: the heart of container woodland care

Rainfall alone will not keep a potted woodland plant alive. Even in a wet British summer, the canopy of a tree or the leaves of a fern shed water away from the pot, and a mature plant can drink its container dry in a day or two.

• Check the compost 5cm down with your finger. If it feels cool and damp, wait. If it feels barely moist, water.
• Water thoroughly until it runs out of the base, ideally in the morning so foliage dries before evening.
• In July and August, expect to water daily, and twice on hot, breezy days.
• Use rainwater where you can – ferns and woodland perennials dislike the lime and salts in tap water.
• Group pots together and shade the containers themselves with other plants or a screen; a pot in full sun cooks its own roots.
• Stand saucers under pots in summer only. Remove them from October onwards so winter rain drains away freely.

Top-dressing, feeding and winter protection

Every March, scrape away the top 3cm of old compost and replace it with fresh loam-based mix. This annual top-dress is the single most useful thing you can do for a confined root system. Fork it in lightly, then scatter a slow-release organic fertiliser – blood, fish and bone at roughly a handful per 40 litres – over the surface. Ferns need only half that amount. Avoid high-nitrogen feeds, which push soft, floppy growth that woodland plants cannot support.

Repot every three to five years, in late winter before growth starts. If roots are circling tightly, tease them out, trim no more than a fifth of the rootball, and move the plant into a pot one size larger. A tree that has reached its final size can simply be root-pruned and returned to the same container with fresh compost.

In winter, raise pots onto feet, wrap them in hessian or bubble wrap, and move them against a sheltered wall. Roots in containers freeze far faster than roots in the ground. Water sparingly but never let the compost dry out completely, and check during mild spells. Do that, and your small woodland will come back stronger each spring.