Pines are among the most distinctive of trees. Unmistakable in parklands and arboreta, they provide dramatic focal points and add character to the skyline. Belonging to the Pinaceae family, the most commonly encountered species in the UK are the native Pinus sylvestris Award of Garden Merit (AGM), the Scots pine, and P. nigra AGM, the Corsican or European black pine. Both are imposing, impressive trees, particularly the black pine, as mature specimen trees often develop heavy, tortuous multiple trunks. While the former is best suited to cooler northern and upland regions of Britain, the latter thrives in the warmer, drier, lowland areas of the Midlands and southern England.
The range extends far beyond these two, though. A substantial number occur as low-growing bushes and larger shrubs, such as P. mugo, a native to mountainous regions of Europe. Besides displaying rich foliage and a distinctive form, conifers carry cones, which add a further decorative feature - not only the familar brown seed-bearing structures but also the often colourful, pollen-bearing strobili or "male cones", which range from golden yellow through to crimson, produced at the beginning of the growing season at the base of the newly elongating shoots or "candles".
Many pines thrive in poor, light soils and dry locations, where their extensive and deep-reaching root systems confer advantage. Even dwarf species will develop substantial root systems from an early age - aiding establishment but limiting options for relocation. Their tolerance of exposed situations and sandy soils also makes them suitable for coastal locations.
Pines should be sited with as much light as possible with a free flow of air. Although intolerant of overshading, they perform well in mixed plantings, where they can give protection to more delicate species - indeed, this is common forestry practice.
The wide range of sizes available means pines can be used in both large and small gardens. The dwarf forms are ideal for container-growing and cope well with the restricted root run. Even larger-growing trees can be so grown, responding by turning into semi-bonsais and surviving for many years. They are also quite forgiving, should they go dry at the roots.
Propagation occurs principally through seeds or grafting. Pines do not take readily to other forms of vegetative mass production such as through cuttings and micro-propagation. Commercially, the favoured method is grafting, and the vast majority of smaller-growing species and varieties will have been subjected to this technique. P. sylvestris AGM is the favoured rootstock for the two-leaved pines, which is the largest group.
WHAT THE SPECIALISTS SAY
- Francis Mizuro, proprietor, Evesham Vale Propagators, Worcestershire
"Twenty years ago, all sorts of pines were being sold and size information could be unreliable. Even now, conifer growers are feeling the impact of this. But a large amount of breeding has been done, and the range has vastly increased for use in small gardens. Our plants are mostly grafted, which is done elsewhere and we grow them on. Grafting tends to be a commercial decision for speed and quantity, but adding a different stock also controls the ultimate size, and most of our range is smaller-growing.
"We find that it's quite a specialist market. The smaller growers are very decorative, beautiful compact plants. Cones are also a definite feature, particularly the male cones, which are often brightly coloured. Pinus parviflora Glauca Group carries red male cones in spring and P. mugo has yellow ones.
"Often people see dwarf varieties and can't believe they are pines. Blues are always popular and there are many good ones, especially P. walllichiana, while P. mugo 'Winter Gold' displays very good winter colour - and the frost brings it out."
- Roger Ward, partner, Golden Grove Nurseries, Lincolnshire
"We are tending to grow those pines that are suitable for small gardens. They are very hardy and will grow in a wide range of conditions but prefer free-draining soils. They are useful in patio pots to give form and colour and their hues will change with the seasons.
"For amenity and landscaping there are some well-coloured forms, like P. sylvestris 'Chantry Blue', a very nice blue that forms a conical shape.
"Most of our conifer stock is grown from cuttings, but pines have to be grafted with a special technique. For two-leaved pines we use P. sylvestris AGM as rootstock, and for five-leaved pines P. strobus. The five-leaved pines are distinctive and have much softer foliage - P. strobus and P. parviflora, for example, appear very densely clothed.
"There is a tremendously wide range of varieties to suit a wide range of situations. Good dwarf varieties are P. densiflora 'Compact Gem', and P. mugo 'Winter Gold', which is green in summer and yellow in winter, P. heldreichii 'Schmittii' is very dwarf and compact and won't get out of hand in any rockery."
- Roger Griffin, Amenity Trees & Landscapes, Arlesey, Bedfordshire
"Some 42 years ago, we were tasked with planting the New Fancy slag heap in the Forest of Dean. it was completely inert and bare, and not even grass would grow on it.
"We planted it up with P. contorta, and now there are trunks over a foot in diameter. They didn't need any special treatment and there was nothing in the soil to support them. As the trees grew and their needles dropped and rotted, we found bracken, birch and other undergrowth taking hold. Generally, pines will accommodate most soils, provided it's not too wet. If you've got a site there is a conifer for it."
SPECIES AND CULTIVARS
- Pinus aristata is famed for its longevity. It grows to little more than 20cm tall and spreads to 30cm after 10 years. Blue-green in colour, it rarely sheds its short, stiff needles.
- P. contorta has several dwarf-growing varieties, such as 'Spaans Dwarf', which grows as a natural bonsai. An ideal choice in poor and infertile soils, it has served well in many land reclamation projects.
- P. densiflora or the Japanese red pine is so named for its flaky red-brown bark. It grows to 20m but is usually encountered as a large shrub in the UK. The 'Pendula' variety is a small, shrubby type, reaching about 1.8m.
- P. heldreichii Award of Garden Merit (AGM), also called leucodermis, is tolerant of extreme cold and exposure. Full-size trees reach around 20m while young cones are a striking dark blue-purple, and the bark has a very distinctive pattern. Dwarf varieties such as "Schmidtii" grow slowly to form a dense deep green cone.
- P. mugo is a small bush to large shrub. Its paired needles are often twisted, while its seed cones are purple when immature. Pollen cones are yellow and the buds together with new growth in spring are often distinctly white. Sizes range from 40cm to 120cm in height and 30cm to 50cm in spread.
- P. nigra AGM has several distinct sub-species, all with dark green needles in pairs and bark that forms a distinctive pattern of large grey-brown plates tending to brown-black in the fissures. In old trees and at trunk bases the bark plates take on a pink-ish hue. They are tolerant of alkaline soils and urban pollution.
- P. parviflora belongs to the five-needled group and is known in Japan as the white pine. The blue-green needles have a pronounced twist, and in spring it bears red pollen cones. The full-sized tree reaches up to 20m but several shorter growing varieties exist.
- P. pinaster AGM grows to 30m. Mature trees form distinctive candelabra-shaped crowns. The seed cones are large and smooth, and the pollen cones are a rich golden colour. It is good for the coast, particularly southern and western parts of the UK, where sandy soils are appreciated.
- P. pinea AGM is an excellent specimen tree, native to south-west Europe, where mature trees earn the name umbrella pine. It reaches 12-20m, and will repay its use with crops of seeds - the "pine nuts" of Mediterranean cuisine. The red-brown bark forms distinctive vertical fissures.
- P. ponderosa AGM is open in growth habit, forming a cylindrical crown and growing to 40m. It has long needles in pairs or threes, deep red-purple pollen cones and bark that flakes in patches, ageing to yellow-orange.
- P. radiata AGM, the Monterey pine, is a medium-sized tree, growing to 20m. It prefers mild conditions in southern and western coastal areas in the UK. The seed cones are large and stay for many years, so even large boughs can sometimes be seen festooned with them.
- P. strobus The Weymouth pine is a large tree to 30m and forms a columnar, open crown. Its long, soft needles droop down, giving it a weeping look, accentuated by the long, narrow, pendulous cones.
- P. sylvestris AGM, the Scots pine, is one of the most widespread - its range spanning much of northern Europe into Siberia. The bark turns orange-red in the upper trunk and into the crown, forming an outstanding contrast with the blue-green needles.
- P. wallichiana AGM is another five-needled pine, whose distinctly blue foliage droops down among the long, pendulous cones. Known as the Himalayan or Bhutan pine, it can be a challenge to transplant and needs a good soil but tolerates periodically wet soils better than many other pines.