Narrowleaf Ash Plant Care

Narrowleaf Ash (Fraxinus angustifolia subsp. oxycarpa) belongs to the Oleaceae family within the Fraxinus genus. Narrowleaf Ash is also known as Caucasian Ash.

Narrowleaf Ash displays a tall, deciduous tree growth habit, reaching up to 80 ft tall with a spread of approximately 40 ft. Narrowleaf Ash produces inconspicuous small clusters.

Leaf size: approximately 6 inches.

Water a young or newly planted Narrowleaf Ash every 7–14 days, soaking the whole root zone, until it is established — usually one to two growing seasons. Established trees mainly need water during long dry spells. In a container, water whenever the top few centimetres of soil are dry.

Narrowleaf Ash thrives in full sun.

Fraxinus angustifolia subsp. oxycarpa tolerates temperatures of 0–100°F. Narrowleaf Ash prefers humidity levels of 30–70%.

Well-draining loamy soil with good fertility. Good drainage is essential for Narrowleaf Ash to prevent waterlogging, which leads to root rot and fungal issues.

Feed Narrowleaf Ash every 8 months during the growing season with a balanced, slow-release fertilizer at the rate on the label. Established trees in good soil often need little extra feeding, so let weak growth or pale foliage guide you.

Stop feeding by late summer so new growth can harden before winter.

The PlantoScan app can remind you when to water and when to fertilize each plant.

Choose a spot with full sun and well-draining loamy soil with good fertility. Avoid low spots where water collects after rain.

Plant container-grown or balled-and-burlapped trees in spring or early autumn, setting the root flare at soil level, and water well after planting.

Narrowleaf Ash can spread to about 40 ft (12.2 m) and reach about 80 ft (24 m) tall. Space plants about 40 ft (12.2 m) apart so mature crowns don't crowd each other, and plant at least half that distance from buildings, fences and paths.

Planning a row or hedge? Try the tree spacing calculator.

Prune Narrowleaf Ash while it is dormant in late winter: first remove dead, damaged and crossing branches, then thin lightly for shape.

If it flowers in spring, prune right after flowering instead so you don't remove next year's buds. Never take off more than about a quarter of the tree in one year.

Water deeply in late autumn before the ground freezes, and spread a 5–8 cm (2–3 in) layer of mulch over the root zone, keeping it away from the trunk.

Young and container-grown trees need extra protection: roots in a pot freeze much more easily than roots in the ground.

Narrowleaf Ash can be propagated through seeds, hardwood cuttings. Similar propagation techniques also apply to european ash plant care, which shares the same genus.

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Narrowleaf Ash is susceptible to aphids, emerald ash borer. Inspect the foliage regularly, especially along leaf undersides and stems. Treat infestations promptly with insecticidal soap or neem oil to prevent spread.

Yellow leaves, brown tips or drooping? See common plant problems and how to fix them.