Fountain Grass (Pennisetum)

How to choose a fountain grass

Fountain Grass is the native swamp foxtail, a green clump to about 1m with plumes from late summer, and the toughest of the three for mass planting and wet or dry ground. Purple Fountain Grass has deep burgundy leaves and long rose plumes to about 1.2m, the plant for a hot border, a gravel garden or a large pot where the colour carries. Dwarf Purple Fountain Grass gives the same colour at about 60cm for the front of a bed or a smaller container.

The trade-off is hardiness against colour: the green native is frost hardy and long lived, the purple forms are at their best in warm districts and in cold ones are treated as summer plants or cut back and mulched for winter.

Where fountain grass works

All three want full sun and free draining soil, and they take heat, wind and dry periods once established. Use them in drifts of five or more along a path, as a soft hedge in front of a wall, between shrubs in a native or Mediterranean style border, at the top of a bank, or in pots on a sunny terrace. The native form also suits the edge of a pond or a damp spot. The purple forms are sterile selections that do not seed, which matters in bushland suburbs. See the other grasses and strappy leaf plants, and the plants for full sun for the borders they sit in.

Planting and spacing

Space the native and the purple fountain grass 60cm to 80cm apart and the dwarf form 50cm apart. Plant level with the soil into ground improved with compost, water in and mulch. In pots use a quality potting mix in a container at least 30cm across for the dwarf and 40cm for the others.

Care basics

Water weekly through the first summer and in dry spells after that. Feed lightly in spring. The one job that matters is the late winter cut: shear each clump back to 10cm to 15cm before the new growth starts and it comes back fresh. The native form can also be cut after the plumes fade in autumn in warm districts. Divide clumps every three or four years in spring. Our guide to ornamental grasses covers the combinations that work with fountain grass.

Common questions

Is fountain grass a weed in Australia?

The wild green form of Pennisetum setaceum is a weed in parts of the country. The purple fountain grasses sold here are sterile selections that do not set viable seed, and the native swamp foxtail is an Australian species.

When should I cut back fountain grass?

Late winter, before the new growth starts. Cut the whole clump to about 10cm to 15cm.

Is purple fountain grass frost tolerant?

Light frost only. In cold districts it dies back and may not return; mulch it heavily or grow it in a pot under cover for winter.

Does fountain grass grow in pots?

Yes, well. Use a pot at least 30cm to 40cm across and water when the mix dries.