New Zealand burr

Sun

Full sun to partial shade; foliage usually colours best in sun.

Water

Water regularly while establishing, then during prolonged dry spells. Avoid persistently wet soil, especially in winter.

Soil

Well-drained sandy, gritty or loamy soil; tolerates modest fertility and a range of soil pH.

Height

0.2-0.3 ft (0.05-0.1 m)

Spread

1.5-3 ft (0.45-0.9 m), spreading farther over time

Flowers

Small, inconspicuous greenish flowers in early to midsummer, followed by conspicuous reddish, spiny seed heads.

Foliage

Tiny, pinnate leaves with toothed leaflets form a dense bronze-green carpet. Usually evergreen in mild climates, but foliage may thin or die back in cold winters.

Growth

Moderate to fast once established, with creeping stems rooting as they spread.

Care needed

Low

• Wildlife
• Low allergen

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Easy

Toughness

Fairly tough

Pick your zone, country, light and whether you have pets.

1. Planting day

   0.1 ft (0.02 m)

2. After 1 year

   0.2 ft (0.05 m)

3. After 2 years

   0.2 ft (0.08 m)

   full size

About 2 years to full size.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Safe

In the garden

Spreads vigorously: plan to contain it.

Growth rate

Fast

• Water new plants when the soil surface starts to dry until they are well rooted.
• Improve drainage before planting in heavy soil; avoid sites that stay wet through winter.
• Feed only if growth is weak; rich feeding encourages unwanted spread.
• Keep gravel mulch light and avoid burying the foliage under bark or compost.
• Lift rooted runners at the edges before they grow into neighbouring plants.

Pruning. In early spring, trim away winter-damaged foliage and shorten wandering stems. Clip off seed heads after their colour fades if you want to reduce burrs and self-seeding.

Early spring

Trim winter-damaged growth and remove stems spreading beyond the intended area.

Spring

Plant or divide into well-drained soil, then water until established.

Early summer

Weed between young plants before the carpet closes over.

Summer

Water during prolonged drought and keep runners clear of small neighbouring plants.

Late summer

Remove unwanted seed heads before burrs disperse.

Autumn

Clear fallen leaves from the mat and check that water drains away freely.

• Use as a low bronze carpet between widely spaced stepping stones where foot traffic is light.
• Plant around rocks and gravel to soften hard edges without hiding the stonework.
• Combine with blue-grey grasses and small sedums for contrasting foliage textures.
• Let it trail over the edge of a raised bed or low retaining wall, keeping it clear of delicate alpines.

Garden styles it suits: Dry gravel garden, Alpine rock garden, Modern, Modern courtyard, Small-space and Low-maintenance.

Plant it with: Blue fescue, Thrift, Rock rose, Hardy ice plant and Low-growing sedums.

Wildlife: The dense mat provides shelter for small ground-dwelling invertebrates. Its burrs can be carried on animal fur; it is not a major nectar plant.

• Winter rot in waterlogged soil: improve drainage or move plants to a raised, gritty bed.
• Unwanted spread into nearby plants: lift rooted runners and trim the perimeter regularly.
• Scorched or thinning foliage during hot droughts: water deeply during extended dry weather and provide afternoon shade in hot climates.
• Burrs catching in fur or clothing: remove seed heads before they mature and avoid planting beside pet routes.

Not known to be toxic to people, cats, dogs or horses, although species-specific toxicity information is limited. The spiny seed heads are a physical nuisance and may irritate skin or become caught in fur; they are not food.

• Spineless acaena (Acaena inermis)

  Its fruiting heads lack the conspicuous long spines of New Zealand burr; foliage colour varies between forms.

• Bidgee-widgee (Acaena novae-zelandiae)

  Usually has larger, greener leaves and a coarser, more vigorous habit; its burrs have hooked spines.

Acaena comes from a Greek word meaning thorn, referring to the spiny fruits, while microphylla means small-leaved.

Propagation. Divide established mats in spring or early autumn, keeping roots attached to each section. Rooted pieces of creeping stem can be lifted and replanted; seed is another option, but seedlings may vary.

Accepted botanical name

Acaena microphylla

Native range

New Zealand North and New Zealand South.

Sources: GBIF (CC BY 4.0) and Trefle (CC BY 4.0). The care and design notes are LandscapeGPT's own.