European beech bonsai

Placement

Two beeches are commonly grown as bonsai: European beech, Fagus sylvatica, and Japanese beech, Fagus crenata. The first has gray bark and broader, oval, wavy-edged leaves up to 4 in long; the second has slightly smaller leaves and silvery white bark. In both, the bark stays perfectly smooth even on very old trees, which sets them apart from hornbeams and their veined bark. The leaves, soft green in spring and then glossy green, turn yellow and orange-brown in fall; many stay on the twigs, dry, until spring and protect the next season’s buds. European beech also comes in many cultivars, with dark purple foliage, weeping branches or deeply cut leaves.

This is an outdoor bonsai all year round. Give it sun or part shade in a well-ventilated spot. Beech does not handle strong heat well: in summer, shelter it from scorching midday sun and from strong wind, which brown and scorch the leaves. The tree is very cold hardy, but in a pot its roots must be protected from frost. In spring, don’t worry if the leaves come out late: that is normal for this species.

Soil mix

A standard, free-draining bonsai mix works well. Drainage matters: a mix that stays soggy encourages root rot. Beech tolerates both acidic and alkaline soils, but watering again and again with very hard water eventually causes chlorosis, a yellowing of the leaves.

Watering

Water as soon as the soil mix starts to dry, never letting it dry out completely, and without overdoing it. Needs rise sharply in full sun or strong wind, especially in a shallow pot, so check the moisture of the mix more often then. In winter, keep the root ball slightly moist. Avoid very hard water.

Fertilizer: on a refined tree, hold off feeding for three to four weeks after the leaves appear, then feed every two weeks until late summer. A tree whose trunk or main branches are still being developed is fed as soon as the leaves unfold. Use a solid organic fertilizer every four weeks or a liquid fertilizer every week, and make sure the tree gets enough micronutrients.

Pruning

Let spring growth extend fully, then cut each shoot back to two leaves, just above a bud that points in the direction you want the future shoot to grow. Large terminal buds can be removed. Thick branches are pruned in spring before the buds open; heavy pruning can also be done in late winter or midsummer. To remove a large branch, choose midsummer, when the wound heals faster. In fall and winter, always leave at least one bud on each pruned twig, or it will die back.

Partial defoliation, which means removing some of the leaves, improves ramification.

Beech suits all formal and informal upright styles, in medium to extra-large sizes. It grows slowly, so be patient.

Wiring

Wiring is possible but calls for great care: the smooth bark marks very easily, and wire scars can stay visible for decades. Wire in late winter, while the tree is bare, using aluminum wire about one third the thickness of the branch, wound at roughly 45°. After spring growth, branches can thicken suddenly and the wire can bite in within just a few days, so watch them very closely and remove wire by cutting it at every turn rather than unwinding it. Don’t bend the same branch over and over, and don’t wire a weak or freshly repotted tree.

Whenever possible, use guy wires instead: a wire or string pulls the branch toward a solid anchor point, such as a root, another branch or the pot, with a piece of rubber or plastic protecting the bark.

Repotting

Repot every two years in spring, as the buds begin to extend and before they open. Older trees are repotted less often, as needed. Use the same standard, free-draining mix.

Beech is easy to grow from seed: sow beechnuts outdoors in fall, or in spring after cold stratification over winter. Cuttings root poorly. Air layering, tried in late spring once new growth has firmed up, does not always succeed.

As for pests, watch for aphids, whiteflies, scale, including mealybugs, and powdery mildew. Treat with a product suited to the pest and improve light and air circulation around the tree. Overwatering leads to root rot, and very hard water to chlorosis. Borers can also move into a tree stressed by heat or drought; a well-watered beech sheltered from too much sun is the best defense. Finally, raw beechnuts are mildly toxic in large amounts, to people and dogs alike.