How to Grow Acaena microphylla Plants in your Garden

Gardener's HQ Guide to Growing Scarlet Piripiri, Rosy Spined New Zealand Bur

The Acaena microphylla plant is known by various names including Scarlet Piripiri, Bronze or Rosy Spined New Zealand Bur, Bronze New Zealand burr, and Scarlet Bidibid.

They are low growing prostate perennials that are great for use as ground cover.

Scarlet Piripiri
Growing Scarlet Piripiri photograph by Vernon Hyde.

As a member of the 100 plus strong Acaena genus, it belongs to the Rosaceae (Rose) family.

This genus is largely native to the southern hemisphere, with Acaena microphylla being a native of New Zealand.

Many Acaena genus members are considered to be invasive in some countries (e.g. Acaena novae-zelandiae in the UK and California).

As Acaena microphylla has a creeping growth habit you should be aware that it may need to be controlled to prevent it spreading from/throughout the garden, and into the local environment.

However, this creeping mat-forming habit can make for a good ground cover plant in the right areas

Acaena microphylla Kupferteppich

Acaena microphylla 'Kupferteppich' Ground cover photograph by Leonora (Ellie) Enking, CC.

As plants can tolerate being trodden on they are ideal for growing in between paving or flagstones.

Acaena microphylla Description Acaena microphylla Description

Acaena microphylla is a prostate mat growing evergreen herbaceous perennial that can reach 10 cm (4 inches) tall, but heights of around 3–5 cm (1.5 inches) are more common.

They usually have a spread to about of 50 to 100 cm (20–40 inches), and it takes two to five years for them to reach their full potential.

Leaves can reach 3 cm (1.2 inches), are a bronze-green color in the spring, pinnate, and have serrated edges.

Flowers appear in the summer, are greenish or white, and carried on tiny purple spikes.

New Zealand burr Photograph

New Zealand Burr by Udo Schröter, CC.

The fruiting heads occur in the summer and early autumn, and are reddish burrs of approximately 2.5 cm (1 inch) in length. These give rise to the plant's common name of New Zealand Bur.

Their low growing mat-forming growth makes them an ideal rockery or ground cover plant. They are also often used for banks, edging, as a container plant, or in a gravel garden.

Acaena microphylla
Acaena microphylla photograph by Leonora Enking

Growing Acaena microphylla

Detailed Acaena microphylla Growing and Care Guide

  • They can grow in full sunlight or partially shaded conditions.
  • Soil type: They require a well-drained soil. Light. Can grow in most soils, but may perform best in sandy soils.
  • Space at about 8 to 12 cm (3-5 inches).

  • Care: Acaena microphylla should be controlled to prevent spreading, do this by pulling out newly rooted stems. Do not let stand in water as this can lead to rot. Cut back in spring. They are easy plants to care for, and are drought and deer resistant.
  • Propagate by division in spring or autumn.

  • The following is a general guide for growing Acaena genus members from seed, and although not specific to Acaena microphylla should provide good results: Sow seeds either after the last frost or in the autumn at a depth of 5 mm (0.2 inches). Germination takes 4 to 12 weeks at a temperature of 10-15°C (50-60°F).
  • Closely related members of the Rosaceae family include Mountain Avens; Meadowsweet; Avens; Cinquefoil; and Rugosa Rose.