Mugo pine

Identification and origin

Pinus mugo belongs to the pine family, Pinaceae. It is native to the mountains of central and southern Europe: from the Alps of eastern France, Switzerland, Germany and Austria to the Carpathians (Poland, Czechia, Slovakia, Ukraine, Romania), as well as the central Apennines and the northern Balkans, down to Albania and Bulgaria. It has naturalized in the British Isles, Scandinavia, the Baltic states and Spain. In the wild, its thickets protect the soil from erosion and slow avalanches. The epithet mugo comes from an Italian name for a small mountain pine.

It is a dense evergreen shrub, often multi-trunked, with a very slow growth rate. Its size varies enormously: in cultivation it is usually 5–20 ft tall, sometimes more, and often spreads wider than it grows tall; dwarf forms stay at 2–5 ft. A plant takes more than fifty years to reach mature size.

The stiff, slightly curved needles, bright to dark green with finely toothed margins, are held in bundles of two and measure 1–3 in. They stay on the plant for about five years and can turn slightly yellow-green in winter. The gray-brown bark is scaly, in irregular plates, and does not peel. The reddish-brown buds are resinous. In spring, new shoots elongate as “candles” before their needles open.

The small pollen cones are greenish yellow. The seed cones, ovoid, dark brown aging to gray-brown, are 1–2 in long, borne singly or in clusters of two to four; they ripen in fall and release small black seeds with a buff wing.

Common cultivars: ‘Mops’, a dense ball 20 in – 3.5 ft tall; ‘Slowmound’ and ‘White Bud’, cushions 2–3 ft tall, the latter with buds coated in white wax in winter; ‘Enci’, a mound 3–4 ft tall; ‘Golden Mound’, golden in winter; ‘Mini Mini’, a 8 in miniature; ‘Tannenbaum’, pyramidal, 10–12 ft tall.

Light

Full sun, at least six hours a day, suits it best. It is one of the few pines that tolerates part shade. It handles windy sites and urban pollution well and suits coastal gardens.

Watering

Once established, mugo pine is quite drought tolerant. It does, however, dislike waterlogged ground: soil that stays wet for several days after rain is not for it.

For the first three years after planting, keep a close eye on it: scratch the soil at the base and water deeply as soon as it is dry below the surface. In sandy soil a young plant needs even more water.

Don’t let the soil go into winter dry: like other conifers, a plant that faces the cold dehydrated suffers more from winter burn, which browns needles from the tip inward. Keep watering in fall during dry spells until the ground freezes. A mulch layer no deeper than 1–3 in, spread over the root zone without touching the trunk, helps hold moisture.

Potting mix

Above all it needs deep, loose, well-drained soil. It grows in loam or sand, copes with clay, poor or alkaline soils, and tolerates acidic to alkaline pH. Only heavy, poorly drained soils are to be avoided.

Avoid nitrogen feeding: it encourages soft shoots that are more vulnerable to tip blight.

Temperature

Extremely hardy, mugo pine is grown in USDA zones 2a to 7b and withstands cold below -4 °F. It prefers regions with cool summers. Winter sun, drying winds and thaws alternating with frozen ground can burn its foliage, especially on south and west sides.

Repotting

Plant it in well-drained soil, allowing for the cultivar’s mature width. With no taproot, it transplants easily.

Dwarf cultivars grow very well in containers on a patio, in a rock garden or at the edge of a pond, in a very free-draining mix. Mugo pine is also a classic bonsai species.

Pruning

It does not need pruning to grow, but light, regular pruning keeps it compact. In spring, once the candles have elongated and before their needles expand, remove one-half to two-thirds of their length, by pinching or with hand pruners. Never cut back into older wood farther down the branch: a pine forms buds only at the tips of the current year’s shoots and does not resprout from old wood. That is why it is best to choose a cultivar of the right size from the start.

Remove dead, diseased, broken or crossing branches at any time.

Propagation

The species is grown from seed: cones are collected in fall when ripe and release their winged seeds. The resulting seedlings vary widely in height, habit and color.

To get plants identical to a particular cultivar, growers use grafting: this is how ‘Mops’ and the other dwarf varieties are produced.

Common problems

• Old needles devoured by colonies of gray-green larvae with black heads: European pine sawfly, in spring. It does not eat the current year’s needles and does not kill the plant; spot-treat colonies if needed.
• Scale insects stuck on the needles: pine needle scale.
• Stunted new shoots, short brown needles, resin on twigs: Diplodia tip blight, favored by wet weather at bud break. Cut out and discard affected shoots, rake up fallen debris and avoid nitrogen fertilizer.
• Needles browning from the tip as winter ends: winter burn.
• Others: aphids and adelgids, pine shoot moth caterpillars, rust, needle cast diseases, honey fungus and root rot in poorly drained soil.

The same symptom can have several causes: before treating, check whether old or new needles are affected, and check drainage and the previous fall’s watering. Deer rarely browse it.

Toxicity

No toxicity is reported: mugo pine is not among the plants listed as toxic to dogs and cats. In Bulgaria its needles are even used to make tea.