Scots pine

The Scots pine is the only pine native to Britain, the tree of the Caledonian forest and of sandy heaths across England, and one of the most widely distributed conifers in the world, from Spain to Siberia. It is a two-needle pine with short, twisted, blue-green needles and a bark that turns a warm flaking orange on the upper trunk and branches with age. In the wild it grows straight when crowded and crooked when alone, and old specimens flatten their crowns into the broad, layered silhouette that a pine bonsai aims to capture.

It suits a temperate garden because it was made for one. Where the Japanese black and white pines that fill the books sulk in a cool, cloudy summer, the Scots pine grows on. It is fully hardy, it tolerates poor soil, and it shortens its needles readily under bonsai culture, which the imported pines do grudgingly. Good young material is easy to find: forestry seedlings, garden-centre plants of the compact cultivars such as 'Watereri' and 'Beuvronensis', and collected trees from heathland with the landowner's permission.

Beginners go wrong with pines by treating them like a maple. A pine does not sprout from old wood on demand, so a branch cut back beyond its needles is a branch lost; it must be kept dense by working the growth it makes each year, not by cutting hard. The other error is too much water and too little sun. A pine wants the brightest place in the garden and a soil that dries, and it will tell you it is unhappy only slowly, by yellowing from the inside and dropping older needles, by which time the cause is months old.

Through the year it stays outside in full sun. Winter protection is rarely needed for the tree itself, but a shallow pot should be kept out of lying water and moved into a cold frame or against a wall during a hard freeze so the roots are not frozen and thawed repeatedly. Snow on the branches is harmless and worth a photograph; wind is the greater hazard, drying needles when the roots are frozen and cannot replace the water.

The growth cycle is what the work is built around. In spring each shoot extends as a candle, which can be shortened to balance the strength of the tree, the strongest candles cut most and the weakest left. The needles then open and harden through summer. In autumn old needles are pulled to let light into the interior and to even out vigour between strong and weak areas. Scots pine, unlike the Japanese black pine, is a single-flush pine: it is not decandled in summer to force a second set of shorter needles, because it does not have the strength to make them in a cool climate. Buds for next year form at the base of this year's growth, and where light reaches the interior they will also form on older wood, which is how a leggy pine is slowly brought back in.

The wood is strong and springy and holds a wire well, but it also thickens fast in spring, so wire applied in autumn and winter must be watched by May. Young branches can be bent surprisingly far; older ones need raffia or a guy wire and patience. The orange bark on a mature branch is the species' great beauty and is easily rubbed off by careless wiring, so the branches of an old tree are wrapped before they are bent.

Seasonal interest is in the needles and the bark. The new candles in April are pale and upright like small flames; the summer foliage is a dense blue-green; in winter the whole tree takes on a slightly duller, greyer tone, and the orange upper bark shows best against a grey February sky. A well-kept Scots pine looks like the tree on the hill it came from, which is the point of the species and the reason to choose it over a pine from somewhere else.

• Informal upright (moyogi): the natural habit of a mature Scots pine is a trunk with movement and a flat-topped crown, which is informal upright in all but name.
• Slanting (shakan): pines on exposed hillsides lean away from the wind, and a slanting trunk with branches drawn to one side reads true for this species.
• Literati (bunjin): the Scots pine's own old-age form is a tall, bare trunk with a small crown; literati is the species drawn from life.
• Windswept (fukinagashi): the flexible young branches can be set in one direction, and jin on the exposed side suits a tree from a Highland ridge.
• Formal upright (chokkan): a straight, well-tapered trunk with regular branch tiers is possible on young material and gives a classic, if austere, pine.
• Forest group (yose-ue): a group of three or five seedlings on a shallow slab recalls a stand of native pinewood.

2 parts pumice, 1 part akadama, 1 part lava rock (by volume), 3 to 6 mm; a coarser mix than for deciduous trees

Pines want air at the root more than water. A gritty, fast-draining mix keeps the mycorrhizal fungi the roots depend on healthy, and dries between waterings even in a wet summer; a water-retentive mix is the usual reason a pine declines.

A pine takes an unglazed pot, and the Scots pine, with its warm bark, looks best in a brown or iron-red clay rather than a cool grey. The rule of thumb is a length about two thirds of the height and a depth about the width of the trunk base; pines carry a slightly deeper pot than the rule suggests, because a dry, airy root ball is what they need and a very shallow pot dries unevenly.

A rectangle, with or without a lip, suits a strong upright or slanting pine. Literati takes a small round drum or a hexagonal pot that is almost incidental beneath the trunk, and a windswept tree sits toward one end of a shallow, plain oval so the sweep has somewhere to go. Drainage holes must be large and the pot must stand on feet.

Adelgids, the small woolly aphids of pines, show as white fluff at the base of the needles in spring and can be wiped off or sprayed with a horticultural soap. Pine shoot moth bores into the candles and makes them wilt; cut out and bin affected shoots. Scale insects sit on older needles and stems as small brown or white bumps. Aphids on the new growth are a nuisance rather than a danger and a sharp spray of water deals with most of them.

The fungal problems are needle casts and blights, which brown bands on the needles and strip the interior; they are worst in a wet, still summer and are discouraged by light and air through the canopy. Root rot from a wet soil is the usual cause of a pine that yellows and dies back over a season. A pine that drops its oldest needles in autumn is behaving normally.

What every month's line rests on: RHS H7: hardy in severe winters. In a shallow pot the roots are less hardy than the tree, so the risk is a root ball that freezes and thaws daily rather than cold itself..