Oyster Plant

Oyster Plant (Acanthus mollis) is the answer to a dry, shaded bed under established trees, the position that defeats most perennials. It throws up glossy, deeply lobed leaves to about 1.2m tall and a metre across, then sends tall spires of white and purple hooded flowers above them in late spring. Planted 80cm apart it makes a bold, architectural groundcover that needs almost nothing.

Why you'll love it

• It works in dry shade. Once established it copes with the root competition and low light under a big tree, which is the hardest brief in any garden.
• Leaves with real presence. Each one is 60cm or more of glossy, sculpted green, the shape carved into the top of a Corinthian column.
• Frost hardy and drought tolerant. A cold southern winter and a dry summer both pass without intervention, and poor, stony ground is fine if it drains.
• Flower spikes that carry. Close to a metre of white and purple hooded blooms held clear above the foliage, worked steadily by bees.

Where it works best

Mass planting and groundcover. Plant 80cm apart for a bold massed groundcover. The big leaves overlap by the second season and shade out most weed seedlings.

Under trees and shaded borders. A long strip on the south side of a house, or the dry ring under an established shade tree, is where it earns its place.

Feature planting. A single clump against a rendered wall or beside steps reads as sculpture in a formal or Mediterranean style garden.

Growing oyster plant in Australia

Position and climate. Part shade to full shade is ideal, and it takes morning sun in cooler districts, though hot afternoon sun scorches the leaf edges. It suits subtropical, warm temperate, cool temperate and Mediterranean gardens, and being frost hardy it handles cold inland and southern winters.

Soil. Free draining is the only requirement. It accepts poor and stony ground happily, and a little compost at planting speeds establishment.

Water and feed. Water weekly for the first summer while the fleshy roots go down, then it is genuinely drought tolerant. Feeding is optional. It may go semi dormant through a hot dry summer, then flush again with autumn rain.

Pruning. Cut the flower spikes off at the base once the seed capsules dry, both for tidiness and to limit self seeding. A hard cut back in late winter brings a clean flush of new foliage.

What to expect when it arrives

It is grown as tube stock, 140mm pots in packs of ten and 200mm pots in packs of six. Tubes are the value option for a large shaded bed and catch up within two seasons. The 140mm and 200mm plants arrive with several full leaves and read as a real plant straight away.

Large soft leaves crease in transit, so expect folding and a torn edge or two. Trim them off and the next flush covers it. Keep the bed damp for six weeks, and expect noticeable spread in the second season rather than the first. Delivered Australia wide, delivery from $29.95, and every plant carries our 30 day healthy plant guarantee.

Plant care guides and related reading

• The best groundcovers for shade in Australian gardens
• Compare the wider groundcover range
• Plants suited to partial shade
• Plants for mass planting

Common questions

Is it invasive?

It spreads strongly, and every fragment of root left in the soil will shoot a new plant, so it is difficult to remove once settled. Plant it where you want it permanently, or contain it with a hard edge such as a path.

Will it flower in deep shade?

The foliage is excellent in deep shade but flowering is lighter. For the tall spikes, give it a position with indirect light or a few hours of morning sun.

Is it safe around children and pets?

It is not listed as pet friendly, and the flower spikes carry stiff, sharp bracts that can prick a hand or a paw. Keep it back from a path edge, and wear gloves when cutting the spikes.