English yew bonsai

Placement

Yew is an outdoor tree in every season. It likes good light but tolerates shade well: it grows even in fairly deep shade, although its foliage becomes less dense there. Part shade therefore suits it very well. In a hot, dry climate, protect it from the scorching afternoon sun in summer.

In winter it stays outside to go through its rest period, but its soft roots dislike hard frost. The tree tolerates cold down to about 14 °F; below that, shelter the root ball, for example in a cold frame. Also protect the foliage from icy winds and strong winter sun, which can damage it badly. Like any evergreen, it needs a bright spot through the winter.

Keep it out of reach of children and pets, and wear gloves when handling clippings: foliage and seeds are highly toxic. The English yew plant profile covers its toxicity and how to grow it in the ground.

Pests and diseases: yew resists nearly every disease except root rot, which overwatering encourages. Bronze or bronze-red needles often point to waterlogged soil or, at the other extreme, drought. As for insects, watch for scale, including yew scale, mealybugs and tortrix moth caterpillars. Vine weevil is the most serious threat: adults chew foliage and bark, while their white, C-shaped grubs eat the roots inside the pot, mostly from fall to spring. A tree that wilts for no obvious reason deserves a look at its root ball. Nematodes applied in late summer, while the soil is still warm, between 41 °F and 68 °F depending on the nematode species, keep the grubs in check; when repotting, remove any you find.

Soil mix

Yew roots hate standing water. Use a very free-draining bonsai mix; pumice is especially popular and helps keep the tree healthy. A standard mix also works, with a little more organic matter in hot climates to hold water better. Yew tolerates a pH between 5 and 8, so it is not fussy on that front.

Watering

Water by observation, never on a fixed schedule. As soon as the surface of the soil starts to dry, soak the whole root ball thoroughly, then let the excess drain away. Do not keep the roots constantly wet: that is the leading cause of root rot in yew. The tree also enjoys being misted with lime-free water.

Fertilizer: during the growing season, apply a solid organic fertilizer every four weeks or a liquid fertilizer every week.

Pruning

Yew takes pruning better than most conifers. It buds back from old wood and even sprouts on bare areas, which makes it possible to rebuild branching or shorten a collected tree drastically.

• Structural pruning: hard pruning and branch removal are done in fall.
• Pinching: during the growing season, pinch or pluck new shoots that stick out of the silhouette. If you want to keep the red fruit, stop pinching after spring flowering.
• Thinning: in summer, shorten shoots and remove old needles so light reaches the interior of the tree. This encourages back-budding and ramification.
• Encouraging buds: in late fall, pluck needles that are two or three years old; new buds often appear in their place the following spring.

Deadwood: yew wood is very hard and lasts a long time, which makes it one of the best materials for jin (a stripped branch) and shari (a strip of trunk without bark). Before stripping bark from the trunk, locate the live veins carefully; with age they form characteristic ridges. Work deadwood in early spring or late summer, when the tree heals quickly, then apply lime sulfur to bleach the wood and protect it from rot.

Styles: yew suits every style and size except broom. Deadwood is one of the hallmarks of old yews. Its thin, reddish-brown bark peels away in grayish flakes along the trunk.

Wiring

Wire can go on in any season, but only on a vigorous, healthy tree; let a weak or freshly repotted tree regain strength first. For a conifer, annealed copper wire holds better than aluminum. Choose wire about one third the thickness of the branch and wrap it at roughly 45°.

Young twigs bend easily; old branches become stiff and brittle. Wrap them in damp raffia before bending, apply force on the inside of the curve and do not bend the same spot repeatedly. Branches take several months to hold their new position, often longer in a slow species like yew. Check the wire regularly and remove it by cutting it at each turn, without unwinding, before it marks the bark.

Repotting

Yew grows slowly: repotting every three or four years is enough, and very old trees can wait longer. Repot in spring, as the buds extend; late summer and early fall also give very good results, because root growth peaks then. The tree tolerates fairly heavy root pruning. Use repotting as a chance to inspect the root ball and remove any vine weevil grubs.

Propagation:

• Seed: sow outdoors in fall, as soon as the seed ripens; germination can take two years or more.
• Cuttings: take semi-ripe cuttings from late summer to early fall, often by tearing small twigs off the branches of the parent tree.
• Air layering: in late spring.