Spring arrives slowly in a shady garden. While sunny borders are already fizzing with daffodils, the damp corner under the old wall is still holding its breath. That pause is a gift, because it gives you a window to tidy, feed and divide your ferns and woodland plants before they commit themselves to a new season. Once those croziers start to uncurl there is very little you can do without snapping something precious, so use March and early April well.

Clear Away the Old Before the New Appears

The single most useful job is also the simplest: cut back last year's foliage. Evergreen ferns such as Polystichum and Blechnum keep their fronds through winter, but by spring those fronds are often battered, brown at the tips and flopping over the crown. Follow them down to the base and cut them off cleanly with sharp secateurs, working around the outside of the clump first so you can see what you are doing. Leaving them in place smothers the new growth and gives slugs somewhere to hide.

Deciduous ferns are easier still. By the time you read this, most will be no more than a ring of brittle stalks and a knuckle of dormant buds at soil level. Snip the stalks away and clear the debris from the crown. Do not bury the growing point under mulch or leaf litter, as this is a common cause of ferns that sulk and never quite get going.

While you are in among them, pull out the usual shade-garden travellers: hairy bittercress, willowherb seedlings, ivy that has crept in from the boundary, and the inevitable ash or sycamore seedlings. Get them now while the soil is soft and their roots come away in one piece.

Divide Crowded Clumps While Growth Is Dormant

Ferns tell you when they need splitting. The centre of the clump goes bald and woody, the fronds form a tight ring around the edge, and the whole thing sits proud of the soil like a doughnut. Left alone, the plant loses vigour and the dead middle becomes a soggy rot spot.

Lift the clump with a fork, working it free gently rather than levering at the crown. Then either:

• Cut straight through the crown with a sharp spade, discarding the woody centre and keeping the healthy outer pieces.
• Tease the sections apart by hand for smaller, more fragile species such as Athyrium and Dryopteris.
• Use two forks back to back, pushed into the middle and eased apart, for tight crowns that resist a knife.

Replant the divisions at the same depth they were growing before, water them in well, and keep them watered through their first summer. A little blood, bone and fish meal raked into the top inch will help them settle. Early spring is the ideal moment because the roots are active but the fronds are not yet unfurled, so there is far less transpiration stress.

Feed and Mulch the Shade Border

Woodland plants are used to a steady drizzle of leaf litter and the slow decay that comes with it. In a tidy garden they rarely get it. A generous mulch in early spring restores that natural cycle and, just as importantly, keeps moisture in the ground through summer.

Spread two to three inches of well-rotted leaf mould, composted bark or garden compost over the border, but keep it clear of crowns, stems and the necks of hellebores. Leaf mould is the best of the lot for ferns, hostas, epimediums, wood anemones and trilliums, because it is low in nutrients and mimics the conditions they evolved in. If you have a supply of your own, this is the moment to use it.

If the soil is heavy clay and prone to sitting wet, fork in some grit or coarse bark at the same time. Ferns like moisture but they do not like waterlogged roots, and a waterlogged crown in March is a dead crown by May. For dry shade under trees, add a good layer of organic matter every year, but do not try to dig deeply among tree roots. Mulch on the surface and let the worms do the work.

Plant, Move and Plan Now, Not Later

Spring is the best planting window for ferns and most shade perennials. The soil is warming, rainfall is usually reliable, and plants have time to root before the dry spells arrive. Bare-root and freshly divided stock establishes far more quickly now than in autumn on cold, wet ground.

Choose your species to match the shade you actually have, not the shade you wish you had. Dry shade beneath a mature tree calls for Dryopteris filix-mas, Polypodium and epimediums. Damp shade suits Osmunda, royal ferns, Athyrium and candelabra primulas. Deep, still shade under a north wall is the place for hart's tongue fern and Asplenium scolopendrium, which will sit there cheerfully for decades.

This is also the time to reposition anything that has drifted out of place, and to lift and pot on seedlings of hellebores, brunnera and pulmonaria before the slugs find them. Label anything you divide. You will not remember which piece was which by July, and a well-labelled fern collection is a pleasure to tend.

Get Ahead of Slugs, Weevils and Late Frost

Ferns are remarkably trouble-free, but their young croziers are soft, sweet and irresistible. Slug damage on unfurling fronds is the main reason ferns look tatty by June. Go out after dark with a torch during wet spells, and use whatever barrier or biological control you prefer around the most precious crowns. Beer traps sunk to soil level still work well.

Vine weevil larvae can hollow out the roots of potted ferns and shade plants in a single season. If a plant in a pot looks limp despite damp compost, tip it out and check the rootball. Early spring is the moment to deal with it, before the adults emerge.

Finally, keep a fleece or cloche handy. A sharp late frost will not usually kill a hardy fern, but it will scorch fresh fronds and leave them brown at the edges for the whole season. A little protection on a cold April night is well worth the effort.

Do these jobs in the quiet weeks before the canopy closes over and the garden fills with green, and your shade borders will reward you all summer with fresh, unblemished fronds and a calm, layered beauty that no sunny border can quite match.