Spring: Mulch, Moisture and a Watchful Eye

Spring arrives slowly in Britain, and trees respond to soil temperature rather than the calendar. This is the moment to give roots a head start before the canopy takes off. Apply a mulch of well-rotted leaf mould, garden compost or woodchip around the base of young and mature trees alike, spreading it to a depth of five to eight centimetres. Keep it clear of the trunk — a hand's width of bare soil prevents damp bark, which invites rot and fungal problems.

Mulch on damp ground in March or April, before weeds get going. It locks in moisture, suppresses grass and slowly feeds the soil food web. Check ties and stakes on any tree planted in the last three years. The tie should hold the stem steady but allow a little movement; trees that sway gently grow stronger trunks. Look for frost damage on new shoots and clip it out once the risk of hard frost has passed.

Native trees are already busy. Blackthorn blooms on bare stems, hawthorn follows, and oak comes last — old country wisdom holds that you should wait for the oak before trusting the weather. Rowan and wild cherry flower alongside the first brimstone butterflies.

Early Summer: Water Deeply, Watch Closely

Once the leaves are fully out, water becomes the limiting factor. A young tree needs roughly ten to twenty litres a week in dry weather — that is one or two full watering cans poured slowly around the root zone, not a daily sprinkle. One deep soak a week encourages roots downwards; frequent light watering encourages weakness. Do it in the evening so less is lost to evaporation.

Clear grass and weeds within a metre of the trunk. Competition at the base is one of the commonest reasons newly planted trees sulk. Resist strimming near bark — the wounds are a gift to disease. Hand-weed instead, or top up the mulch.

Pull off suckers rising from the rootstock rather than cutting them, as tearing removes the bud that would regrow. Watch for aphids on the soft tips of field maple and cherry; leave them where ladybirds and blue tits are working through them, and only intervene if growth is badly distorted.

High Summer: Shade, Shelter and Signs of Stress

By July, established woodland trees are looking after themselves, but young ones and anything in a pot or a dry border still need you. Signs of drought stress include curled or yellowing leaves, early leaf fall and a thin canopy. If a tree sheds leaves in August, it is protecting itself; keep watering and it will usually recover next spring.

Replenish mulch if it has thinned. Avoid feeding with anything high in nitrogen after midsummer, as soft late growth will not harden before the cold. Hold off on hedge cutting until nesting season is over — August or early September is kinder to birds, and light trimming of hawthorn, blackthorn and hazel can then be done safely. Hazelnuts and acorns are swelling, and the first jays will soon be caching the autumn harvest.

Autumn: The Best Time to Plant

From November through to March, bare-root trees are available and cheap, and warm, damp soil lets roots establish before winter. Choose natives suited to the ground: alder and willow for wet, heavy soil; birch and rowan for lighter, acidic ground; field maple, crab apple and wild cherry for most gardens; oak where there is room for a proper forest giant.

Plant at the same depth the tree grew in the nursery — the soil mark on the stem tells you. Dig a square hole rather than a round one, fork the base to break up compaction, and firm gently after backfilling. Stake only if the site is exposed, and fit a spiral guard against rabbits. Water well, even in November.

This is leaf mould season. Sweep leaves into bin bags or a wire frame and leave them for a year or two — oak, beech and hornbeam take longest, while lime and sycamore break down quickly. It is the finest mulch you can make. Leave a few piles in quiet corners for hedgehogs and overwintering invertebrates.

Winter: Pruning, Planning and Dormant Repairs

Dormant pruning is best done between November and February, though avoid working in hard frost. Apples, pears, hawthorn, field maple and oak can all be tidied now: remove dead, diseased and crossing wood, and take out any branch rubbing against another. Make clean cuts just outside the branch collar, never flush to the trunk.

Two important exceptions. Leave plums, cherries and other stone fruits until summer, as winter wounds invite silver leaf disease. Birch, acer and walnut are also best pruned in late summer to avoid bleeding sap.

Walk the garden after gales and deal with broken limbs promptly; torn stubs decay and can let in honey fungus. Check young trees for frost heave, where roots are lifted by freezing and thawing, and firm them back in. Replace or adjust guards that have become too tight.

Finally, use the quiet months to plan. Note gaps in your planting, order bare-root trees for collection in the new year, and consider coppicing a hazel stool on a rotation for pea sticks and kindling. Winter is also when the shape of a woodland is most visible — a good time to ask whether a tree has outgrown its space, before it tells you itself.