Why a Seasonal Calendar Works

Trees do not ask much of us, but they do keep to a schedule. Their roots push, their buds swell, their leaves fall and their sap retreats, all in a rhythm that shifts only slightly from Cornwall to Caithness. When you match your own work to that rhythm, everything becomes easier. You prune when the tree can heal, you water when it is thirsty rather than when it is convenient, and you clear the ground when the pests and spores are looking for somewhere to overwinter. This simple calendar is the one most arboriculturists carry in their heads. It is not rigid, and a mild winter or a wet August will nudge timings, but it gives every garden a sensible framework.

Spring: Mulching and the Season of Growth

Spring begins underground, often weeks before you notice anything above it. As the soil warms and roots start to move, this is the finest moment to mulch. A layer of well-rotted manure, composted bark or last year's leaf mould, spread 5–8cm deep, will hold moisture through summer, suppress weeds and feed the soil life that feeds the tree. Keep it clear of the trunk — leave a 10cm collar of bare earth so the bark stays dry and disease-resistant. Mulch mounded against a trunk is one of the most common causes of rot in young trees.

Spring is also the time to check the hardware. Look at stakes and ties on any tree planted in the last three years. Ties should be firm but never cutting in, and you should be able to slide a finger beneath them. Remove a stake that has done its job; a tree left tied too long will never build the trunk strength it needs. If you have rabbit or deer pressure, check tree guards and replace any that have split.

• Mulch before the ground dries out, ideally March to mid-April.
• Slacken or remove tree ties and stakes as growth demands.
• Water newly planted trees during any dry spell, even in spring.
• Watch for late frosts on blossom; avoid heavy pruning of fruit trees in a cold snap.

Summer: Watering, Watching and Gentle Pruning

Summer is a test of patience. A young tree needs roughly 20 litres a week in dry weather, delivered slowly to the root zone rather than sprinkled over the leaves. Water deeply and less often — a good soak every seven to ten days encourages roots to descend, while daily light sprinkling teaches them to stay near the surface. Older, established trees rarely need irrigation in a British summer unless the season is exceptional.

Summer is also the best time for the pruning jobs that winter cannot handle. Plums, cherries and other Prunus species should be pruned between June and August, when silver leaf spores are least active and wounds seal fastest. The same applies to acers, which bleed heavily from winter cuts. Light thinning of overgrown branches is fine in summer, but go gently: heavy removal now can expose bark to scorching and stress the tree when it can least afford it.

Spend the warm months watching. Greenfly, scale insects, caterpillars and honey fungus all show themselves now, and an early eye is worth a late cure.

Autumn: Leaves, Planting and Roots

Autumn is the busiest season for tree care, and the most generous. Raking leaves does more than tidy the lawn. Leaves left thickly under a tree can smother grass, harbour fungal spores and give pests a winter home. Rake them into a wire bin or a black sack with a few holes, and by next autumn you will have leaf mould — a superb, free mulch for woodland and ericaceous plants. A useful rule: clear leaves from lawns, paths and pond margins, but leave a thin scatter under mature trees and hedges where wildlife benefits. A light layer is habitat, not litter.

Autumn is also planting time. Bare-root trees, lifted and sold between November and March, establish far better than container-grown stock and cost less. Plant on a mild, frost-free day into a hole three times the width of the root ball but no deeper than the original soil mark. Firm gently, water well, and stake only if the site is exposed. Fruit trees, hedges, field maples, rowans and oaks all love an autumn start.

• Rake and compost fallen leaves, especially beneath roses and fruit trees.
• Plant bare-root trees from November once leaves have dropped.
• Check drainage around established trees in heavy clay after autumn rain.
• Remove dead or diseased wood while it is easy to see.

Winter: Pruning, Structure and Planning

Once leaves are gone, the tree's frame is laid bare, and this is when most structural pruning should happen. Deciduous trees are dormant, sap is low, and wounds made now will begin sealing before growth resumes in spring. Start with the three Ds — dead, diseased and damaged wood — then thin crowded branches and remove rubbing limbs. Use sharp, clean tools, make cuts just outside the branch collar, and never leave a stub.

Two cautions matter in a British winter. Do not prune in hard frost or when rain is due for days; wet cold wounds invite infection. And do not prune Prunus species now, however tempting the bare branches look. Silver leaf is a genuine risk, and those trees are far safer trimmed in summer.

Winter is also the season for planning. Walk your boundaries and note which trees have outgrown their space, which are shading a vegetable bed, and which need professional attention. Anything involving a chainsaw, a ladder above head height, or a tree near a building or power line is a job for a qualified tree surgeon — and winter is the easiest time to book one.

A Year of Small Habits

None of this is onerous. A mulch in spring, a soak in summer, a rake in autumn and a considered prune in winter will keep most garden and woodland trees healthy for decades. The trees will do the growing; your part is simply to turn up at the right moment, with the right tool, and to leave the rest to them.