Japanese yew

Identification and origin

Taxus cuspidata belongs to the Taxaceae, the yew family. Its native range stretches from the Russian Far East (Primorye, Sakhalin, the Kuril Islands) to northern China, Manchuria, Korea and Japan. It has naturalized locally elsewhere, notably in the northeastern United States, where it was introduced in 1833. In Japan it is called ichii.

In the wild it is an upright tree that can exceed 49 ft in height; in cultivation it usually forms a small tree or a large spreading shrub 10–25 ft tall and 5–10 ft wide.

• Needles: evergreen and linear, 1–1 in long, arranged in a spiral but appearing to spread in two ranks, sometimes raised in a V along the twig. They are glossy dark green above with two wide tawny bands beneath, and end in a short point. In winter they can yellow or take on a reddish-brown tint.
• Bark: reddish brown and thin, flaking off in patches on older plants.
• Cones and “fruit”: the species is dioecious. Male plants bear tiny pale yellow-green pollen cones in spring. Female plants bear naked seeds half wrapped in a bright red fleshy aril, which ripens from late summer into fall and is often clustered and more abundant than on English yew.

Japanese yew has been crossed with English yew (Taxus baccata) to produce Taxus × media, a group of hybrids that combine the vigor of the latter with the hardiness of the former. Among its cultivars, ‘Capitata’, a pyramidal form, is the only one that becomes a true tree; spreading ‘Nana’ slowly reaches 10 ft and gradually grows up to twice as wide.

Light

Japanese yew grows equally well in full sun or dense shade and suits any exposure. It grows denser in good light, but partial shade protects it in winter from strong winds and reflected sun, which dry out the foliage. In hot, dry climates, shield it from harsh afternoon sun in summer.

Watering

It prefers moist but never soggy soil: waterlogged ground rots its roots. Once established, it tolerates occasional drought. Rather than following a schedule, check soil moisture deep down during dry weather, especially around young plants. Its shallow roots benefit from mulch, which keeps the soil moist and moderates its temperature. Water deeply in fall before the ground freezes to limit winter desiccation.

In a container, water as soon as the mix starts to dry and never let the root ball dry out, but don’t keep it wet all the time. Misting the foliage with lime-free water does it good.

Potting mix

Choose well-drained sandy or loamy soil rich in organic matter, preferably slightly acidic to neutral; yew tolerates a pH between 5 and 8. What it fears most is heavy, poorly drained soil. In a planter, use a very free-draining mix rich in mineral components such as pumice.

Temperature

It is one of the hardiest yews: it grows in USDA zones 4a through 7b and withstands continental winters below -4 °F. More than cold itself, it is often drying wind and winter sun that brown the foliage when the ground is frozen and the roots can no longer take up water. Mulch, a burlap screen or a temporary shelter limit this winter burn.

In a container the roots are more vulnerable: protect the root ball during severe cold, for example by burying the pot.

Repotting

Plant it in well-prepared, well-drained soil, spacing plants at least 6 ft apart in a group planting. In a container, repot every three or four years in spring as the buds extend; the roots tolerate pruning well.

Pruning

Japanese yew takes pruning very well, even hard pruning: it resprouts from old wood where no needles remain. Annual pruning keeps it in shape; a hedge is trimmed in late summer, or more often for a very formal look. Where winter burn is common, however, avoid late-summer pruning, and in spring, before new growth starts, cut out any parts damaged over winter. Wear gloves, as the plant is toxic.

Propagation

• Cuttings: the most common method for ornamental yews. Take semi-ripe cuttings from late summer to early fall.
• Seed: yew seeds have deep, variable dormancy. Sown outdoors as soon as they ripen, they often don’t germinate until the second spring. To break dormancy, keep them warm for several months, at around 61–64 °F, then cold for several more, at around 36–41 °F, before sowing them under 0–1 in of soil. Seedlings are often male.
• Layering: possible in late spring.

Common problems

Black vine weevil is the main enemy of yews: the night-feeding adults notch the foliage and bark, while the larvae eat the roots from summer into fall and in early spring, sometimes with no visible sign on a container plant. Yew scale forms small, domed brown shells on the twigs; a light population is harmless, but a heavy infestation weakens the tree and lets sooty mold grow on the honeydew. Mealybugs, tortrix moth caterpillars and gall mites can also appear.

As for diseases, Phytophthora root rot is a threat in waterlogged soil, and twig and needle blights are also reported. Deer readily browse yew. Browning needles can come from frost, wind, excess water or a root pest: the same symptom can have several causes.

Toxicity

Japanese yew is highly toxic to dogs, cats and horses. It contains alkaloids called taxines in the bark, needles and seeds. In small animals, eating it causes digestive upset, tremors, breathing difficulty, seizures and a slow heart rate, and can be fatal; in horses it can cause collapse and sudden death.

In people, the seeds are the most toxic part, and the plant is most poisonous in winter. Poisoning can cause confusion, breathing difficulty, bluish skin, dilated pupils, an abnormal heartbeat and tremors; symptoms last one to three days and can require a hospital stay. The red flesh of the aril is not toxic, but the seed inside it is highly so. Contact with the foliage does not irritate the skin.