Repotting guide

When & how to repot Scarlet Bidi-Bidi (Acaena microphylla)

Also called Scarlet Bidi-Bidi, New Zealand Burr, Scarlet Piripiri.

More about scarlet bidi-bidi

About Scarlet Bidi-Bidi

Acaena microphylla · also called Scarlet Bidi-Bidi, New Zealand Burr · flowering

Scarlet Bidi-Bidi is a vigorous, carpet-forming perennial from New Zealand grown for its bronze-green finely divided foliage and showy spherical scarlet-red burr heads in late summer. It hugs the ground tightly, making it ideal for rockeries, gravel gardens, and path edges. Very low maintenance once established in a free-draining site.

Mature size: 5–8 cm tall, spreading to 60–90 cm or more

How to tell scarlet bidi-bidi needs repotting

Repotting on a calendar is less reliable than reading the plant. For scarlet bidi-bidi, watch for these signs:

Roots growing out of the drainage holes, or the rootball lifting the plant proud of the rim.
Soil that has shrunk away from the pot sides and no longer holds water.
The pot is unstable because the plant has grown top-heavy.
Old, compacted, broken-down mix that stays wet too long — for a succulent that is a rot risk, so refresh it even if the pot size is fine.

For the underlying biology of a pot-bound root system and why it stalls a plant, see our guide to spotting and fixing a root-bound plant.

How often to repot scarlet bidi-bidi

Every 2–3 years, into bone-dry mix. Scarlet Bidi-Bidi's growth habit — prostrate, mat-forming perennial with spreading stems rooting at nodes; forms a low, dense carpet — sets the pace. Scarlet Bidi-Bidi is a vigorous, carpet-forming perennial from New Zealand grown for its bronze-green finely divided foliage and showy spherical scarlet-red burr heads in late summer. It hugs the ground tightly, making it ideal for rockeries, gravel gardens, and path edges. Very low maintenance once established in a free-draining site.

What size pot to step scarlet bidi-bidi up to

Use a pot only one size up — or even the same pot with fresh gritty mix if the roots have room. Scarlet Bidi-Bidi stores water and rots in a large pot of slow-drying soil. A tight terracotta pot that dries fast is far safer than a generous plastic one. Never up-pot a succulent by several sizes.

Not sure of the exact diameter? Our pot size calculator takes the current pot and root spread and tells you the right next size — it deliberately recommends a single step up, never a big jump.

The best time of year to repot scarlet bidi-bidi

Spring or summer, while scarlet bidi-bidi is in active growth and warm, is best — roots recover fastest then, and the plant is not sitting in cool damp soil. Avoid repotting a succulent in winter dormancy.

Step-by-step: repotting scarlet bidi-bidi

Repot dry. Do not water scarlet bidi-bidi for several days first. Working with dry roots and dry mix dramatically lowers the rot risk for a succulent.
Pick a snug, fast-draining pot. Choose terracotta one size up at most, with a drainage hole. Have gritty gritty, well-drained, average to poor fertility ready.
Tip it out and clean the roots. Slide the plant out, crumble off the old soil, and trim any black, mushy or dead roots with clean snips.
Pot into dry mix. Set scarlet bidi-bidi at its original depth in dry gritty mix, firming gently. Do not bury the stem deeper than it was.
Wait a week before watering. Leave it completely dry and out of harsh sun for about 7 days so any damaged roots callus. Only then water lightly.

Aftercare

Keep scarlet bidi-bidi completely dry and out of fierce sun for about a week so any nicked roots callus before they meet moisture; watering a freshly repotted succulent is the classic way to rot it. Then resume the normal lean, dry rhythm. Do not fertilise for about 3 weeks — fresh mix already carries nutrients and feeding freshly disturbed roots scorches them.

The right soil mix for scarlet bidi-bidi

Scarlet Bidi-Bidi wants gritty, well-drained, average to poor fertility. Thrives in sandy, gritty, or gravelly soils where drainage is excellent. Does not require fertile soil; overly rich conditions promote lush, floppy growth rather than the tight, compact mat that gives the plant its ornamental appeal. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting scarlet bidi-bidi — frequently asked questions

How often should you repot scarlet bidi-bidi?

Every 2–3 years, into bone-dry mix for scarlet bidi-bidi. Repot scarlet bidi-bidi every 2–3 years into a snug pot of gritty, well-drained, average to poor fertility, ideally in spring or summer. Let it sit in dry soil and do not water for about a week afterwards so any nicked roots can callus. Over-potting and watering straight away is what rots succulents.

What size pot does scarlet bidi-bidi need?

When is the best time of year to repot scarlet bidi-bidi?

Should you water scarlet bidi-bidi after repotting?

No — not straight away. Repot scarlet bidi-bidi into dry mix and wait about a week before the first watering so any damaged roots callus over. Watering a freshly repotted succulent is the single most common way to rot one.

Should you fertilise scarlet bidi-bidi after repotting?

Not immediately. Wait about 3 weeks after repotting scarlet bidi-bidi. Fresh mix already contains nutrients, and feeding freshly cut or disturbed roots burns them. Resume your normal feeding routine once you see new growth.