Repotting guide

When & how to repot African Cornflag (Chasmanthe aethiopica)

Also called African cornflag, Small cobra lily, Pennant flower.

More about african cornflag

About African Cornflag

Chasmanthe aethiopica · also called African cornflag, Small cobra lily · flowering

African cornflag is a vigorous, winter-growing cormous perennial from the fynbos and coastal scrub of South Africa, producing tall, sword-like leaves and arching spikes of vivid orange-red tubular flowers in late winter to early spring. In mild, frost-free climates it grows outdoors year-round; elsewhere the corms must be lifted and stored dry over winter. The single most critical care requirement is strict summer dormancy — corms left in wet soil during their dry-season rest will rot. Chasmanthe aethiopica is not listed as toxic by the ASPCA but, as a precaution with corms of uncertain status, treat as mildly toxic to pets.

Mature size: 60–120 cm tall in flower; clumps spread to 30–60 cm, multiplying vigorously over time.

Watch for — Corm rot from summer moisture: The leading cause of failure — corms sitting in moist soil during summer dormancy will rot rapidly. Lift corms after foliage dies down, store in a cool dry place in paper bags, and replant in autumn; or grow in pots that can be moved under cover.

How to tell african cornflag needs repotting

Repotting on a calendar is less reliable than reading the plant. For african cornflag, 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 african cornflag

Every 2–3 years, into bone-dry mix. African Cornflag's growth habit — clump-forming cormous perennial producing upright, pleated, sword-like leaves from which emerge arching, one-sided flower spikes bearing tubular blooms. — sets the pace. African cornflag is a vigorous, winter-growing cormous perennial from the fynbos and coastal scrub of South Africa, producing tall, sword-like leaves and arching spikes of vivid orange-red tubular flowers in late winter to early spring. In mild, frost-free climates it grows outdoors year-round; elsewhere the corms must be lifted and stored dry over winter. The single most critical care requirement is strict summer dormancy — corms left in wet soil during their dry-season rest will rot. Chasmanthe aethiopica is not listed as toxic by the ASPCA but, as a precaution with corms of uncertain status, treat as mildly toxic to pets.

What size pot to step african cornflag up to

Use a pot only one size up — or even the same pot with fresh gritty mix if the roots have room. African Cornflag 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 african cornflag

Spring or summer, while african cornflag 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 african cornflag

Repot dry. Do not water african cornflag 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 fertile, free-draining loam or sandy loam 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 african cornflag 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 african cornflag 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 african cornflag

African Cornflag wants fertile, free-draining loam or sandy loam. Plant corms in well-draining soil enriched with compost; a gritty mix prevents the waterlogging that causes corm rot during the all-important summer dormancy period. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting african cornflag — frequently asked questions

How often should you repot african cornflag?

Every 2–3 years, into bone-dry mix for african cornflag. Repot african cornflag every 2–3 years into a snug pot of fertile, free-draining loam or sandy loam, 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 african cornflag need?

When is the best time of year to repot african cornflag?

Should you water african cornflag after repotting?

No — not straight away. Repot african cornflag 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 african cornflag after repotting?

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