Baby corms: when to separate them and how to propagate your Alocasia

August 22, 2026

Alocasias don't multiply by leaf or stem cuttings like a Monstera: they do it by corms, small storage organs that the plant forms at the base and that, once separated, give a new plant. It's the method with which we grow almost everything we sell in the corms section, and it's easy to do at home if you respect a couple of rules.

Where they are and when they appear

Baby corms form underground, around the main corm or joined to it by a filament, and sometimes on the rhizome that stays under the stem. They appear mostly on mature, healthy plants, at the end of the growing season and after a winter rest. They range from the size of a pea to a walnut, hard, brown on the outside and white inside.

When to separate them

When repotting in spring is the best time: the plant is already disturbed and the corm gets going with warmth.
Corms from 1 cm. The smaller ones sprout, but take months and rot easily; better to leave them attached another season.
If the offset already has its own roots or a leaf, separate it carefully so as not to break those roots: it's a “rooted” corm and goes straight into substrate.
Don't separate offsets from a sick or stressed plant: save the mother first.

How to do it

Take out the plant, loosen the substrate with your fingers and locate the corms. The ones that come away on their own, out; the very stuck ones, with a clean knife.
Remove the dry outer layer if it comes off on its own (the “shell”); that way you see whether the corm is healthy and it absorbs moisture better.
Let the cut dry for a couple of hours. Optional: a little ground cinnamon on the wound, which helps keep fungi out.
Set them to sprout with warmth and humidity following the tub method. Roots in 2-4 weeks, first leaf a few weeks later.
Replant the mother in fresh mix; it usually appreciates the space and puts out a leaf quickly.

Other ways to propagate

Division: some large species (Macrorrhiza, Odora, Zebrina) form clumps with several growing points that can be split with roots. Seed: only for pure species; slow, and in variegated ones it doesn't pass on the variegation. Tissue culture: it's lab work, not home work; many cheap plants on the market come from there.

Does the offset come out the same as the mother?

On a green Alocasia, yes: it's a clone. On a variegated one, not always. Variegation is a mutation that affects some cells and not others; the baby corm inherits the proportion of variegated cells from the area where it formed, which can be high, low or none. That's why a corm from an albo mother can give a very variegated plant, a green one or an almost-white one that doesn't survive, and that's why in our listings we show the mother plant but never guarantee the variegation of the offset. What is always inherited is the species and the “potential”: a corm from a green mother will never give a variegated one.

If you have spare corms of a rare variety and don't know what to do with them, store them as we explain in Alocasia in winter or send us a photo at info@marinasjunglegems.com.

Texto redactado con ayuda de inteligencia artificial y publicado por el equipo de Marina’s Jungle Gems.