Oak
Quercus robur and Quercus petraea
Hedgerows, field boundaries and old gardens everywhere in Cornwall. Sessile oak dominates the valley woods.
- How hard
- Takes a moderate reduction, up to about 25% of the crown in one visit.
- Best time
- Late autumn to late winter, once the leaves are off, or in high summer when the tree is in full leaf.
- Avoid
- Spring, while the buds are breaking, and the weeks after. Oak recovers slowly from big wounds, so cuts are kept small and back to a growth point.
Why it usually needs work
- •Branches spreading over a roof, drive or neighbour's garden
- •Heavy shade on a house or lawn
- •Dead wood over paths, parking and play areas
- •Storm damaged or split limbs after a south westerly
- •Keeping a large tree in proportion to a small garden without removing it
A mature oak is often the most valuable tree on a property, for wildlife and for the look of the place. Reductions are kept modest and repeated on a cycle rather than done hard once. Oaks with cavities and loose bark are prime bat roosts, so we look before we climb.
Hedgerows, lane sides and woodland edges across the county.
- How hard
- Takes a moderate reduction, up to about 30% of the crown in one visit.
- Best time
- Winter, November to February.
- Avoid
- Nothing seasonal in particular, but the tree's condition matters more than the month. Ash dieback is now in every part of Cornwall.
Why it usually needs work
- •Ash dieback: dead tops and brittle limbs over roads, gardens and buildings
- •Fast, whippy regrowth after an earlier cut
- •Limbs over lanes and power lines
- •Reducing sail area on an exposed tree
Check the crown before planning anything. An ash with dieback goes brittle from the top down, and once it is badly affected it usually cannot be climbed safely, which changes the job from a reduction to a dismantle with a platform or crane. A healthy ash takes a reduction well and regrows readily.
Sycamore
Acer pseudoplatanus
Self seeded almost everywhere: gardens, hedges, shelter belts and behind sheds.
- How hard
- Takes hard cutting and pollarding, up to about 40% of the crown in one visit.
- Best time
- Mid summer, or late autumn and early winter after the leaves have dropped.
- Avoid
- Late winter and early spring, when a maple bleeds sap heavily from every cut.
Why it usually needs work
- •Dense shade and honeydew from aphids dripping on cars and patios
- •Seedlings spreading across the garden
- •Outgrowing the space, often having been ignored for years
- •Crown too heavy for a tree squeezed against a wall or bank
Sycamore is a tough, fast tree that takes a hard reduction or a pollard in its stride and comes back thick. The trade off is vigour: a hard cut means a repeat visit every few years, so a moderate reduction on a longer cycle is often the better plan.
Parkland, larger gardens and old estate plantings around Truro, Falmouth and the Roseland.
- How hard
- Light pruning only, up to about 20% of the crown in one visit.
- Best time
- Late summer, August into September, or mid winter.
- Avoid
- Spring, and any heavy thinning that suddenly exposes bark to full sun. Beech bark scorches and dies back.
Why it usually needs work
- •Crown out of proportion for its setting
- •Lifting low branches for light and mowing
- •Dead wood in a big old crown
- •Bracing or reducing a heavy limb over a building
Beech does not sprout well from bare wood and its thin bark resents being opened up, so the rule is little and often: cuts under 75 mm, no more than a fifth of the crown, and a light crown lift rather than a hard reduction. Shallow roots mean keeping vehicles and building materials off the ground under the canopy.
Monterey pine
Pinus radiata
The big flat topped pines on the coast, in shelter belts and around older houses from Falmouth to St Ives.
- How hard
- Light pruning only, up to about 10% of the crown in one visit.
- Best time
- Autumn or winter, in dry weather.
- Avoid
- Cutting back into bare wood at any time: a pine does not regrow from it, so whatever is cut off is gone for good.
Why it usually needs work
- •Heavy limbs over houses, roads and parking
- •Dead wood and hanging branches after storms
- •Crown lifting for light and access
- •Thinning to reduce the sail on an exposed tree
You cannot make a Monterey pine smaller in any real sense. The work that suits it is dead wooding, lifting, removing individual heavy limbs and occasionally light thinning. A big pine that has genuinely outgrown its place is a dismantle rather than a prune, and that is a crane or platform job on most sites.
Monterey cypress
Cupressus macrocarpa
The huge dark evergreens along the south coast, on the Roseland and in Victorian gardens. Often planted as a screen and now enormous.
- How hard
- Light pruning only, up to about 15% of the crown in one visit.
- Best time
- Spring through to late summer, never in frost.
- Avoid
- Cutting past the green growth. Like most conifers it stays brown where it has been cut into bare wood.
Why it usually needs work
- •Overgrown screen blocking light and views
- •Large limbs tearing out in gales
- •Trunk and roots too close to walls and drains
- •Reducing a topped tree that has grown a heavy, unstable crown
Macrocarpa can be trimmed within the green growth and lightly topped, but it cannot be brought back from a big overgrown tree to a neat screen. Old specimens shed limbs in wind, so dead wooding and weight reduction on long laterals is the usual work. Removal and replanting with something smaller is often the honest answer.
Coastal gardens, seafront shelter belts and towns such as Falmouth and Penzance, where it shrugs off salt wind.
- How hard
- Takes hard cutting and pollarding, up to about 35% of the crown in one visit.
- Best time
- Late spring into summer, after the risk of frost and while it is growing.
- Avoid
- Winter cuts on an evergreen that is not growing, which stay open for months.
Why it usually needs work
- •Dense year round shade on a house or neighbour
- •Blocking a sea view
- •Leaf drop in early summer clogging gutters
- •Keeping a big evergreen in check near a building
Holm oak is one of the few large trees that can be reduced hard, even clipped, and come back dense. It is the ideal choice for a coastal screen that needs holding at a fixed size, but it grows steadily and needs doing on a regular cycle.
Hawthorn
Crataegus monogyna
Every Cornish hedge, field corner and cliff top. Wind sculpted on the coast.
- How hard
- Takes hard cutting and pollarding, up to about 50% of the crown in one visit.
- Best time
- Late autumn to late winter, outside the nesting season.
- Avoid
- March to August, when it is almost certain to have birds nesting in it.
Why it usually needs work
- •Reclaiming a hedge that has grown up into a line of trees
- •Thorny growth over paths, gateways and lanes
- •Letting light back into a field edge or garden
- •Restoring an old hedge by laying or coppicing
Hawthorn can be cut back to a stump and will come again. If it is part of a hedgerow the best long term fix is laying or coppicing in rotation rather than trimming the top every year. Leave the berries where you can: they feed thrushes and winter migrants.
Cornish hedges, scrub and coastal slopes, spreading by suckers into fields and gardens.
- How hard
- Takes hard cutting and pollarding, up to about 60% of the crown in one visit.
- Best time
- Late autumn to late winter.
- Avoid
- The nesting season, and handling it without gloves and eye protection: the thorns cause nasty infected wounds.
Why it usually needs work
- •Thickets taking over field edges and lawns
- •Suckers spreading under fences into neighbouring ground
- •Thorns over footpaths and stiles
- •Clearance ahead of fencing or hedge laying
Blackthorn comes back from anything, and cutting it encourages suckering, so clearance without dealing with the roots is a short lived win. For a hedge it lays beautifully and makes an impenetrable stock proof barrier.
Woodland edges, old coppice and hedgerows in the valleys.
- How hard
- Takes hard cutting and pollarding, right down to the ground.
- Best time
- Winter, November to February.
- Avoid
- The nesting season. Dormice use hazel too, so a wood with dormice needs a plan before cutting.
Why it usually needs work
- •Overgrown coppice stools that have become heavy and are splitting
- •Multi stemmed clumps shading a garden
- •Bringing a neglected hedge back into rotation
- •Producing poles, bean sticks and firewood
Hazel is meant to be cut to the ground every seven to ten years. A stool coppiced in winter throws up a dozen new straight stems by the following summer, so there is no such thing as pruning a hazel too hard, only cutting it at the wrong time of year.
Streamsides, damp corners, the edges of ponds and anywhere wet. Goat willow seeds itself into gardens.
- How hard
- Takes hard cutting and pollarding, up to about 60% of the crown in one visit.
- Best time
- Late autumn to late winter, while dormant.
- Avoid
- Nothing seasonal beyond nesting birds, but willows are brittle, so the work is done before a limb fails rather than after.
Why it usually needs work
- •Brittle limbs tearing out over a stream, garden or road
- •Fast growth swamping a pond or boundary
- •Roots seeking drains and soakaways
- •Bringing an old pollard back into cycle
Willow will regrow from a stump and is the classic pollard tree. It grows so fast that a hard cut is normal and a light one is a waste of a visit. Crack willow in particular drops limbs without warning, so anything over a path or building is best kept small on a regular cycle.
River banks, wet woodland and boggy field corners, often alongside willow.
- How hard
- Takes hard cutting and pollarding, up to about 50% of the crown in one visit.
- Best time
- Winter.
- Avoid
- Cutting during the nesting season, or removing bankside alders wholesale, which destabilises the bank they are holding together.
Why it usually needs work
- •Leaning trees over a watercourse
- •Coppicing to keep a riverside line open
- •Dead or dying trees from Phytophthora root disease
- •Clearing space for a fence, track or drain
Alder coppices readily and is often best managed that way along water. Phytophthora alni is present in Cornish river systems and kills the roots, so a thin, yellowing alder on a bank is worth having looked at rather than pruned.
Birch
Betula pendula and Betula pubescens
Gardens, heathland edges and the fringes of old mine ground where little else grows.
- How hard
- Light pruning only, up to about 20% of the crown in one visit.
- Best time
- Late summer to early winter, August to December.
- Avoid
- Late winter and spring, when a cut birch bleeds sap for weeks. It is also a short lived tree that rots from large wounds.
Why it usually needs work
- •Overhanging a roof or gutter
- •Lifting the crown to mow or park beneath it
- •Dead wood in an older tree
- •Leaning stems on an exposed site
Birch dislikes heavy pruning and does not fill back in afterwards. Keep to a light thin, a crown lift and dead wooding. A birch that is too big for its spot is usually one to replace with a smaller tree rather than fight.
Cornish elm
Ulmus minor subsp. angustifolia
Hedgerow lines and lane sides in west Cornwall, regrowing from suckers after Dutch elm disease.
- How hard
- Takes hard cutting and pollarding, up to about 40% of the crown in one visit.
- Best time
- Winter, when the elm bark beetle is inactive.
- Avoid
- April to August. Fresh cuts in summer attract the beetle that spreads Dutch elm disease.
Why it usually needs work
- •Sucker growth turning into a thicket along a boundary
- •Dead tops from Dutch elm disease over a lane
- •Keeping hedgerow elms as a trimmed line
- •Removing dying stems before they drop
Cornish elm keeps coming back from the roots after each round of disease, so most of what you see is young sucker growth that takes hard cutting well. Anything large and dying is removed in winter and the wood taken away, not stacked, to avoid breeding beetles.
Small gardens, moorland edges and Bodmin Moor, and planted widely as a street tree.
- How hard
- Takes a moderate reduction, up to about 25% of the crown in one visit.
- Best time
- Late winter, in dry weather.
- Avoid
- Wet weather. Rowan is in the apple family and open cuts in the wet invite fireblight and canker.
Why it usually needs work
- •Crossing and rubbing branches in the crown
- •Lifting low limbs over a path or drive
- •Removing suckers and dead wood
- •A light reduction to keep it in scale with a small garden
Rowan needs little more than a tidy: crossing branches out, dead wood off, a light lift. It is a naturally neat tree and a hard reduction spoils the shape for years.
Hedges, woodland understorey and as a specimen in older gardens.
- How hard
- Takes hard cutting and pollarding, up to about 50% of the crown in one visit.
- Best time
- Late winter, or late summer for a trim.
- Avoid
- Hard frost, which browns fresh cuts, and the nesting season: holly is a favourite nest site.
Why it usually needs work
- •An overgrown holly shading a window or path
- •Reshaping a specimen that has gone leggy
- •Cutting a holly hedge back to a line
- •Removing a self seeded holly from under a bigger tree
Holly regrows from old wood and can be cut back hard, even to a stump, and comes back dense. It is slow, so a hard cut takes a few years to look right, but it always does.
Cherry
Prunus avium and ornamental cherries
Gardens and streets everywhere; wild cherry in hedges and woods.
- How hard
- Light pruning only, up to about 20% of the crown in one visit.
- Best time
- Summer only, June to August, in dry weather.
- Avoid
- Autumn and winter. Cuts made then let in silver leaf and bacterial canker, which kill cherries branch by branch.
Why it usually needs work
- •Branches over a roof or blocking a window
- •Dead wood and cankered limbs
- •Roots lifting a path or lawn
- •Crown lifting for light beneath
Cherry is the one tree where the calendar matters more than anything else. Summer pruning, small cuts, and no hard reductions: a cherry cut back hard throws water shoots and dies back around the wounds. If it is far too big, replacing it is kinder than butchering it.
Apple and pear
Malus domestica and Pyrus communis
Old orchards, garden trees and the odd survivor in a hedge.
- How hard
- Takes a moderate reduction, up to about 25% of the crown in one visit.
- Best time
- Winter, December to February, for shape and renovation. Summer for holding a tree at a size.
- Avoid
- Taking more than a quarter of the crown in one winter. The tree answers with a forest of water shoots and no fruit.
Why it usually needs work
- •Restoring a neglected orchard tree over two or three winters
- •Opening the centre for light and air, and fewer fungal problems
- •Removing canker, dead wood and crossing branches
- •Bringing fruit back within reach
An old apple is renovated in stages, never in one go. The aim is an open goblet with a few well spaced main limbs, and a few years of patience. Mistletoe is common on Cornish apples and is worth keeping in moderation.
Eucalyptus
Eucalyptus gunnii and others
Planted in gardens across the county in the 1980s and 1990s and now far bigger than anyone expected.
- How hard
- Takes hard cutting and pollarding, up to about 60% of the crown in one visit.
- Best time
- Late spring to early summer, so the regrowth hardens before winter.
- Avoid
- Autumn and winter, when soft new growth after a cut is caught by frost and wind.
Why it usually needs work
- •Far too big for a garden, and still growing fast
- •Shallow roots and a tall crown on a windy site
- •Bark and branches shedding on to lawns and cars
- •Trunk too close to a house or boundary wall
Eucalyptus regrows from the base and from a pollard and can be cut back hard every couple of years to keep it as a shrubby, silver leaved plant. Left to become a tree it is brittle, top heavy and shallow rooted, which is why so many come out after a winter storm.
Leylandii and other conifers
Cupressus x leylandii, Thuja, Chamaecyparis
Screens and boundaries in every housing estate, now often 15 m tall.
- How hard
- Light pruning only, up to about 30% of the crown in one visit.
- Best time
- April to August, never in frost.
- Avoid
- Cutting the sides back past the green growth. The brown stays brown for good.
Why it usually needs work
- •A screen that has become a wall of trees blocking light
- •Neighbour complaints and the 2 m high hedge rules
- •Roots drying the ground under a lawn or patio
- •Reducing height on trees that have got away
Height can come off a leylandii, and the tree will green over the top in time, but width cannot go back past the green. If the sides are already bare inside, the choice is to live with the size, reduce the height only, or take them out and replant with something you can keep small.
Churchyards, old gardens and as clipped specimens. Some Cornish churchyard yews are many centuries old.
- How hard
- Takes hard cutting and pollarding, up to about 40% of the crown in one visit.
- Best time
- Late summer, or spring before growth starts.
- Avoid
- Frost, and any work near livestock: the clippings are poisonous to grazing animals and must be cleared completely.
Why it usually needs work
- •Reshaping an overgrown specimen
- •Lifting for light and access in a churchyard or garden
- •Reducing a yew that is shading graves, paths or a building
- •Bringing a topiary shape back
Yew is the one conifer that regrows from bare wood, so even a neglected tree can be brought back in stages. Ancient yews are treated as veterans: minimal work, staged over years, and nothing at all without good reason.
Sweet chestnut
Castanea sativa
Old estates, parkland and coppice woodland in the sheltered valleys.
- How hard
- Takes hard cutting and pollarding, up to about 35% of the crown in one visit.
- Best time
- Winter.
- Avoid
- Heavy work on an old tree without checking for decay first. Big chestnuts hollow out and hold together on a shell of sound wood.
Why it usually needs work
- •Heavy limbs on a mature tree over a lawn or drive
- •Dead wood and storm damage
- •Coppicing for poles and fencing
- •Reducing a veteran that is beginning to shed its crown
Sweet chestnut coppices readily and takes reductions well when young. Old specimens are a different matter: they are spectacular, often hollow, and the aim becomes keeping them standing safely with staged reductions rather than tidying them up.
Horse chestnut
Aesculus hippocastanum
Village greens, school grounds, parks and larger gardens.
- How hard
- Takes a moderate reduction, up to about 25% of the crown in one visit.
- Best time
- Winter, once the leaves are down.
- Avoid
- Hot dry spells in summer. Horse chestnut is one of the species prone to summer branch drop, when a heavy limb fails on a still day for no visible reason.
Why it usually needs work
- •Bleeding canker weakening limbs and stems
- •Heavy limbs over play areas, roads and parking
- •Dead wood after leaf miner and canker have weakened the tree
- •Crown lifting over paths and pavements
Most horse chestnuts in Cornwall now carry leaf miner, which browns the leaves by August, and many have bleeding canker on the trunk. Neither is a reason to prune on its own, but a tree with canker around a limb needs that limb looked at closely before it is trusted over people.
Lime
Tilia x europaea and Tilia cordata
Avenues, churchyards, town streets and old gardens.
- How hard
- Takes hard cutting and pollarding, up to about 40% of the crown in one visit.
- Best time
- Winter.
- Avoid
- Nothing seasonal, but a pollarded lime needs re-cutting on a regular cycle: the regrowth is fast and weakly attached if left for decades.
Why it usually needs work
- •Honeydew from aphids covering cars and paving beneath
- •Sucker growth at the base and along the trunk
- •Keeping an avenue or street tree at a set size
- •Reducing a heavy, previously pollarded crown
Lime pollards and regrows from old wood better than almost any other large tree, which is why so many street limes are managed that way. Epicormic shoots around the base are a fact of life and are cleared as routine.
Scots pine
Pinus sylvestris
Heathland, old plantations, the edges of mining country and larger gardens.
- How hard
- Light pruning only, up to about 10% of the crown in one visit.
- Best time
- Autumn or winter, in dry weather.
- Avoid
- Any cut back into bare wood, and removing the leader on a young tree, which ruins the shape for good.
Why it usually needs work
- •Dead wood in the lower crown
- •Lifting for light and access
- •Removing a heavy limb over a building
- •Felling a leaning tree on shallow ground
Like the Monterey pine, a Scots pine cannot be reduced, only tidied. Its shape is its value: a tall clean stem and a flat, open crown. Dead wooding and a crown lift are the whole toolkit.
Cornwall's great gardens and, from them, thousands of suburban front gardens.
- How hard
- Light pruning only, up to about 15% of the crown in one visit.
- Best time
- Mid summer, after flowering and once in full leaf.
- Avoid
- Winter and spring, when cuts bleed and die back, and any hard reduction: magnolia does not regrow to a shape.
Why it usually needs work
- •Branches over a path, drive or window
- •Removing dead, crossing or storm damaged wood
- •A light lift to walk beneath
- •Reshaping after wind damage
Magnolias are pruned as little as possible. A few well chosen cuts in summer are fine; a reduction is not. Big old magnolias in Cornish gardens are landmarks and are treated with the same care as any veteran.
