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Ailanthus altissima - Growing Guide

Growing Ailanthus Altissima

Tree of heaven

This is a hardy deciduous tree introduced to the UK in the mid-18th century and now widely grown in cities and parkland. Its leaves and fruits are very similar to those of Fraxinus (ash) although, as far as we yet know, the genus is not susceptible to ash dieback disease.

The tree grows best in deep, fertile soil in sun or partial shade. Its pinnate leaves are up to 2ft long and composed of up to 30 ovate or lance shaped leaflets which are reddish green when they open turning mid-green. This tree commonly produces root suckers which should be cut off (or dug up with roots to create new trees) to preserve the energy going up into the main trunk.

Like Paulownia, Ficus carica and Catalpa this is a tree which can be cut to ground level each winter and allowed to regrow from the stump. A. altissima will produce new shoots of 8-10ft in height each year so that the large leaf structures can be admired in a shrub border.

A. altissima can produce male or female flowers. Occasionally trees will produce both. Male flowers have an unpleasant scent and can cause an allergic reaction. Sadly it is impossible to tell which seedlings are which sex until they are large enough to flower. Where male and female trees grow together the small green female flowers will develop quantities of attractive red-brown fruit. The fruits are in groups of three to five seeds and are produced in 9-12in branching panicles. Each seed or fruit has a peculiar twist at each end (like ash) so that they revolve rapidly when they fall and can be distributed well away from the parent tree.

A. altissima is easily grown from ripe seed sown in containers. The trees grow 60-80ft in height with a spread in maturity of 30-50ft.

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