Green Ash Fraxinus pennsylvanica

This is the species form of green ash, normally raised from seed, the parent of the named street clones, and it is the ash to reach for when the ground itself is the problem. It comes from river flats and bottomland across eastern and central North America, so it accepts heavy clay, soil that lies wet for weeks after rain, alkaline ground and hard winter frost, then carries on through a dry summer once its roots are down. The result is a broad, rounded deciduous shade tree with large pinnate leaves, mid green and lightly glossy, that usually turns clear yellow before it drops.

Growing from seed cuts both ways. Every tree differs a little in shape, vigour and autumn tone, which hardly matters in a paddock shelter belt or a park but shows in a formal avenue where trees are meant to match. Green ash trees are also either male or female, and a seedling could be either. Females carry heavy crops of narrow winged seed that hang on into winter before they fall.

Heavy clay, hard frost and the sites other trees refuse

Give it full sun. It is at its most useful on the cold tablelands, in the ACT, inland Victoria and southern New South Wales, and in heavy, slow draining garden ground that lies wet after rain, provided that water does not run off to a creek or dam. It also grows in warmer districts, though autumn colour is brightest where autumn nights turn properly cold. Water it through its establishing years; after that it copes with dry spells, although a deep soak in drought stops the canopy thinning.

Two warnings. The first is roots. This is a big, thirsty tree with a wide, spreading root system, and like other large ash it belongs well away from sewer and stormwater lines, septic trenches, paving and house footings. The second is seed. Green ash has already naturalised along creeks and drainage lines in the ACT, and seedlings pop up readily in mulched beds below a female tree. If your block runs down to a creek, a wetland or bushland, plant a local native instead: ACT planting standards say green ash, even the seedless clones, should not go near nature reserves, creeks or watercourses.

Seedling green ash or a named clone

Three of the Ash Trees here are green ash, and the two named clones are both male and set no seed. Urbanite is the street pit specialist, darker in leaf and bronze in autumn. Cimmaron is a pyramidal tree that broadens with age and turns burgundy to brick red in autumn, a more even and predictable shape for a street or park row. The seedling species is the broader and looser tree, the one to plant in numbers for shelter, for shade across a paddock or a large garden, and for heavy ground away from waterways where uniformity is not the point.

Structure first, then a light feed

Seedling ash often forks low, and a fork with bark pinched into the join is where a large tree eventually splits. Prune in winter while it is bare: settle on one leader early, remove rivals while they are still thin, and space the main branches up the trunk with wide angles. A light spring feed of slow release fertiliser is plenty, because heavy feeding only produces soft, weak wood. Mulch the root zone, keeping the mulch clear of the trunk, and pull any ash seedlings that appear in nearby beds while they are small enough to come out by hand.

Choosing a size

This plant is available in 9 sizes, from 300mm up to 750L, priced from $109.00 to $4699.00 per plant. The size shown is the pot the plant arrives in, which is the rootball, not the height of the plant. Every size here is established stock rather than a starter plant, so this line is intended for immediate effect rather than for growing on. Not sure which to choose? Read our guide to choosing a tree for a small backyard.