Chinese quince bonsai

Placement

Give Chinese quince a sunny, airy spot outdoors: sun encourages growth, flowering and fruiting alike. The tree is very tolerant of both cold and heat and responds strongly to temperature: as soon as spring warms up, it grows vigorously.

It handles a little frost, but in a pot its roots are exposed: protect it from hard frost and cold winds. A cold frame makes a good winter spot.

Possible pests include aphids, scale insects and weevils; treat with a suitable product if they get out of hand. The most dreaded disease is fire blight, a bacterial infection. The Chinese quince plant profile covers the tree’s other diseases.

Soil mix

It grows best in neutral to slightly acidic soil. A standard, free-draining bonsai mix suits it: for a deciduous tree, for example, half akadama, a quarter pumice and a quarter lava rock. Sift the akadama and lava rock to remove the dust, which would eventually clog the pot. If you cannot check on the tree often, increase the share of akadama or add a little potting soil to hold more water.

Watering

Keep the root ball slightly moist at all times. Check the pot often and water as soon as the surface starts to dry, until water runs out of the bottom. In summer, when the tree is flowering and then carrying fruit, its needs are high: it should never dry out. Rainwater is best if you can collect it, since it limits the buildup of mineral salts in the soil.

If the root ball has dried out completely, submerge the pot in a basin of water until no more air bubbles rise.

Fertilizer: during the growing season, apply a solid organic fertilizer every four weeks or a liquid fertilizer every week. Choose a balanced fertilizer with enough phosphorus and potassium to support flowers and fruit. Avoid overfeeding, which produces soft shoots that are prone to pests and diseases.

Pruning

Pruning Chinese quince follows the flowering cycle.

• Before flowering: let young shoots grow unpruned until the flowers appear.
• After flowering: cut new shoots that have stretched out back to two leaves.
• Fruit: if a lot of fruit sets, keep only a few. Fruiting wears the tree out, and the weight of the quinces can weaken the branches.
• Overly dense foliage: remove some of the largest leaves to let light in. If that is not enough, cut half the length off the remaining outer leaves at an angle to make them smaller.
• Young trees: remove the flower buds and let the growth run more freely to thicken the trunk and build the branches.
• Heavy pruning: during winter dormancy. Old, healthy and vigorous branches bud back readily.

Styles: fine specimens combine a muscular trunk with mottled bark, roots that grip the soil and undulating branches. The informal upright style, with a curving trunk that carries a branch at each bend, shows off these qualities well. Some museum specimens are a century old or more: one of them, about 3 ft tall, spreads 3.5 ft wide.

Wiring

The best time to wire is fall, after the leaves drop, when the structure is easy to see. Young twigs are flexible and easy to wire; young shoots can also be shaped in summer. Avoid spring: the tender buds snap at the slightest touch.

Old branches become stiff and brittle: to lower them, use guy wires, thin wires anchored to a sturdy root, a strong branch or the pot, protecting the bark where the wire touches it. For coiled wire, choose anodized aluminum, which suits deciduous trees, about a third as thick as the branch and applied at about 45°. Keep an eye on it during the growing season: a branch can grow over it within one to four months. Remove it by cutting it at each turn rather than unwinding it.

Repotting

Repot in early spring, before growth resumes. A young tree is repotted every two years, an older tree every three to five years. Shorten the roots at the same time and replace the soil, which compacts over time. A balanced slow-release fertilizer can be mixed in when you repot. Afterward, keep the tree in a shaded, sheltered spot until it has fully recovered.

Propagation: Chinese quince is propagated from seed, from softwood cuttings in summer or by air layering.