Planting an oak is the easiest thing in the world and the hardest thing to get right. A bare-root whip costs very little, weighs almost nothing, and will — if you give it half a chance — outlive everyone reading this. But oaks are slow to forgive a bad start: the wrong spot, a summer of neglected watering, or a rabbit with an appetite can set a young tree back years. Here is how to do it properly, from choosing the tree to the point where it stops needing you.
Choosing a native oak
Two species dominate British woodlands, and both make fine garden trees if you have the room. Neither is fussy, but each has its preferences, and matching tree to soil saves you a decade of disappointment.
English oak (Quercus robur)
The classic. Leaves with almost no stalk, clustered at the ends of the shoots, and acorns carried on long stalks. It likes heavy, moisture-retentive ground — clay and loam, the sort of soil that sits wet in winter but drains by spring. This is the oak of the English lowlands, and the one most people picture. Given deep loam it will grow steadily and live for centuries; given thin sand it will sulk for a while before giving up.
Sessile oak (Quercus petraea)
Leaves clearly stalked, acorns sitting directly on the twig. Happier on lighter, drier, more acidic soils, and the usual oak of the wetter west and the uplands. If your soil is thin, sandy or peaty, this is the better choice. The two hybridise freely where their ranges meet, so nursery stock is sometimes a mixture — not a problem, unless you are a purist.
Buy bare-root whips between November and March from a nursery or woodland charity selling British-grown stock, and ask about local provenance if that matters to you. Bare-root trees settle faster than container-grown ones and cost far less. A 60–90cm whip will overtake a larger, more expensive tree within a few years, simply because it transplants with less shock. Container-grown oaks can go in at almost any time, but autumn is kindest.
Whatever you choose, plan for the tree it becomes. A mature English oak can top 20 metres with a crown to match. That is not a tree for a small front garden, and no amount of pruning will keep it small without disfiguring it.
Siting: give it room, then give it more
Nearly every problem with a garden oak twenty years from now traces back to where it was planted. Spend longer on this than on anything else.
- Distance. Keep oaks well clear of buildings, drains, patios and boundary walls. Ten to fifteen metres from a house is sensible for a tree destined to reach full size. If your garden is in a conservation area, or there is a tree preservation order nearby, it is worth knowing what that means for the future — your council's tree officer can explain.
- Light. Full sun is best. Oaks tolerate light shade, but growth is slower and the crown more drawn.
- Soil. Most soils will do, provided they drain. Waterlogged ground and very shallow chalk are the exceptions, and on those you should expect slow growth or choose something else.
- What is underneath. Cables, pipes, soakaways and septic tanks all deserve a moment's thought before you dig.
- Acorns. A mature oak drops thousands. Charming in a meadow, tiresome on a driveway.
- Neighbours. Not everyone loves a large tree. A quiet word now is easier than an argument about shade in fifteen years.
Preparing the ground and planting
The single biggest killer of young trees in gardens is competition from grass and weeds. Everything else is secondary. Work through this in order, and you will have done more for your oak than any amount of fussing later.
- Clear a circle at least a metre across of all grass, weeds and their roots. Do not skim over this step.
- Dig a square hole, wider than the roots will spread but no deeper than they need. Square holes discourage roots from circling.
- Fork over the base and score the sides if the soil is compacted. Do not fill the hole with rich compost — the roots should be encouraged out into your own soil.
- Stand the tree in water for half an hour if it is bare-root, and trim any broken roots with clean secateurs. For container-grown stock, water it well and tease out the outer roots.
- Position the tree so the root collar — where the stem meets the roots — sits at soil level. Backfill in stages, firming gently with your heel as you go. There should be no air pockets and no wobble.
- Water thoroughly, at least a full watering can, and let it drain before you finish firming.
- Mulch the cleared circle with 5–7cm of bark, leafmould or well-rotted manure, keeping the material a hand's width clear of the trunk. A mulch that touches the stem invites rot.
Staking: when to bother, and how to do it
Most young oaks should not be staked at all. A tree that is left to flex in the wind builds a thicker trunk and a wider root plate than one held rigid, and it will not need to be weaned off support later. That said, there are times when a stake earns its keep: an exposed, windy site, a very light or sandy soil, a large container-grown specimen, or a whip planted where mowers and footballs are a hazard.
Doing it properly
- Use a short stake — roughly a third of the tree's height, driven in at 45 degrees, angled into the prevailing wind. It should come out of the ground on the windward side.
- Tie the tree to the stake with an adjustable rubber or webbing tie in a figure-of-eight, so the stem does not rub against the timber.
- Check the tie every spring. Loosen it as the trunk thickens, and remove the stake altogether after two or three years. A forgotten tie can girdle a tree.
- Guard against rabbits, hares and deer with a spiral guard or mesh tube at least 60cm tall. Voles gnaw below ground, so keep the base clear of long grass and thick mulch.
Watering and the first summer
A new oak's first two summers decide whether it romps away or merely survives. In a dry spell, water 10–20 litres once a week, poured slowly so it soaks in rather than running off. Little and often is worse than useless, encouraging shallow roots at exactly the wrong depth. Water in the evening or early morning, and soak the whole rooting circle, not just the trunk.
Ten gallons of water given properly in July is worth more than a hundred gallons dribbled about all summer in the wrong place.
Do not mulch the tree again with fresh material in spring on top of old — check the depth, top it up sparingly, and keep the trunk clear. And do not feed it. An oak on decent soil needs nothing, and too much nitrogen produces soft, sappy growth that aphids adore and frost cuts down.
The first five years
Year one
The tree establishes, not grows. Expect very little in the way of extension growth — perhaps a few centimetres, perhaps none. Keep the circle around it clear of weeds all season, water through the first dry spell, and resist the urge to prune anything. Remove only dead or broken wood.
Year two
If it has been happy you will see real shoots forming, often 20–40cm, with a leader rising straight and clean. Remove any competing shoot that tries to become a second leader by rubbing it out while it is still soft. Keep watering in dry weather, and check the guard and tie.
Years three to five
This is where the oak takes over. Growth accelerates, the canopy begins to broaden, and the root system extends well beyond the spread of the branches. By year five, a well-sited tree of 60–90cm may be three or four metres tall, and it no longer needs watering or staking. Once it reaches that point, your job is mostly to leave it alone — and, if you mow beneath it, to widen the unmown circle each year so you never damage the roots or the base of the trunk.
Pests, diseases and wildlife
Oaks support more species than any other native British tree, so a young one will soon play host to things that look alarming and are mostly harmless. Knopper galls, spangle galls and oak apples are the work of tiny wasps and do no lasting damage. Powdery mildew dusts the leaves in a wet summer; it is ugly but survivable. Aphids produce sticky honeydew in June, which ants and ladybirds will deal with for you.
Two things are worth taking seriously. Oak processionary moth, now established in parts of London and the southeast, has caterpillars with hairs that irritate human skin and lungs — nests should be reported, not handled. Sudden oak death, caused by Phytophthora ramorum, is a notifiable disease for which you should contact the relevant plant health authority. Squirrels, jays and mice will take acorns as they fall, and deer will browse the leader; both are reasons to guard more generously than you think necessary.
Common mistakes
- Planting into a lawn and assuming the tree will out-compete the grass. It usually will not, for several years.
- Filling the planting hole with compost, which makes the roots lazy and reluctant to leave their cosy pocket.
- Overwatering — genuinely more common than underwatering in wet western gardens.
- Forgetting the tie, or the guard, for one season too many.
- Pruning hard in the early years in an attempt to shape a tree that will shape itself perfectly well.
Get the siting and the first three summers right, and an oak asks almost nothing of you ever again. Plant it, guard it, water it, walk away. In fifty years someone you will never meet will stand under it in the shade and think nothing of you at all, which is, in the end, the finest thing a gardener can hope for.
Photo: Lauri Poldre / Pexels
