Peppermint Willows (Agonis)

How to choose an Agonis flexuosa

The West Australian Weeping Peppermint is the species: a broad, weeping tree to about 10 metres high and nearly as wide, with a fibrous brown trunk that turns thick and gnarled with age. It is the familiar street and park tree of Perth and the south west, and it suits a large garden where a soft, pendulous shade tree is wanted.

The Dwarf Willow Myrtle is the Nana form, a dense rounded shrub that is clipped as a hedge about a metre high or left as a mound. Agonis flexuosa Afterdark has deep burgundy foliage and grows as a slender large shrub or small tree, well short of the species. The Pink Flamingo Peppermint Willow is another coloured leaf form, also smaller than the species. Both are grown for foliage and work well as a contrast against green or grey plants.

Where Agonis flexuosa grows

Peppermint trees come from the sandy coastal country of south west Western Australia, and they do well in warm temperate and Mediterranean climates: Perth, Adelaide, Melbourne, coastal Victoria and much of coastal New South Wales. They tolerate salt wind, sand, limestone and dry summers once established. They are frost tender when young, so in cold inland districts protect them for the first two or three winters. Established trees take light frost. They dislike tropical humidity, so they are not a tree for the wet tropics, and they are less reliable in the humid subtropics.

Outside south west Western Australia the plain species can seed into coastal bushland, so do not plant it beside reserves.

For related plants, see our Australian native trees, the plants for coastal areas and, for clipped boundaries, the hedging and screening plants.

Planting and spacing

Plant in full sun or light shade in well drained soil. Sandy soil suits them. In clay, plant on a mound or raised bed, because the roots resent sitting wet through winter. Give the species at least six metres from buildings and keep it clear of drains and paving, since it grows into a wide tree with a strong root system. Space dwarf plants 60 to 80 centimetres apart for a low hedge, and allow the coloured leaf forms about two metres. Mulch after planting and keep the mulch off the trunk.

Care basics

Water through the first two summers, then only in long dry spells. Use a low phosphorus native fertiliser in spring if growth is pale. Established trees rarely need feeding. Clip dwarf hedges lightly two or three times through the warm months rather than once hard. The coloured forms can be tip pruned to thicken them, and their colour is strongest in full sun. On the tree, lift the canopy gradually by removing a few low branches each year if you need clearance beneath the weeping growth.

Common questions

How big does Agonis flexuosa grow?

The species reaches about 10 metres high with a wide weeping canopy. The dwarf Nana form stays near a metre, and the coloured leaf forms sit in between, well below the species.

Does the peppermint tree tolerate frost?

Young plants are frost tender and need protection for their first winters. Established trees handle light frost but not the hard frosts of cold inland districts.

Can I grow Agonis in a pot?

The dwarf and coloured leaf forms grow well in a large pot of native potting mix. The species is too big for a pot beyond its first few years.