Gadenin日本語Get the appCuttings do not work, and here is why
People try a calathea leaf in water because it works for so many other houseplants, and it always fails. The leaf stays green for a few weeks, then goes soft and rots. There is nothing wrong with your technique.
A calathea grows from a rhizome, a thickened underground stem, and every leaf comes up from it on its own stalk. That stalk carries no node and no growth point, so a detached leaf has nothing to make roots or a new shoot from. The only way to make a new plant is to take a piece of the rhizome with its own shoots and roots, which is division.
| Method | Does it work? | Comment |
|---|---|---|
| Division of the rhizome | Yes, reliably | The only practical method at home |
| Leaf in water | No | No node on the stalk, so it rots after a few weeks |
| Stem cutting | Not applicable | There is no aerial stem to cut |
| Seed | Technically yes | Rarely flowers indoors and seed is almost never available |
| Tissue culture | Yes, commercially | How nursery plants are produced, not a home method |
Divide in late spring, at repotting time
Division is a repot plus root surgery, so it belongs firmly in the growing season. Late spring into early summer, in a room reliably above 68F (20C), gives the divisions the whole warm season to establish before growth slows.
The plant should be a healthy, full clump with several distinct shoots, and ideally slightly pot bound so the rhizomes are easy to find. Do not divide a plant that is recovering from pests, root rot or a recent move. Divide a strong plant, never a struggling one.
A division taken in autumn goes into the cold half of the year with a damaged root system and a reduced leaf count. Those are the ones that die over winter, and it is timing rather than technique that killed them.
Dividing it, step by step
Have the new pots, the mix and a clear surface ready before you take the plant out. The less time the roots spend in the air, the better the divisions take.
- Water the day before Damp compost falls away from the roots cleanly and the rootball stays together while you work. A dry rootball shatters and tears.
- Slide it out and clear some compost Support the crown, tip the pot and ease the plant out. Work a little of the old compost away from the base with your fingers until you can see where the shoots join the rhizomes.
- Find the natural divisions Look for points where the clump separates into groups of shoots with their own roots. Often you can simply pull these apart with your thumbs. Take the divisions the plant offers rather than the ones you want.
- Cut only where you must Where a rhizome will not separate by hand, cut it with a clean sharp knife. Wipe the blade between cuts. A crushed or torn rhizome is the usual entry point for rot.
- Keep each division big enough Every piece needs at least three or four healthy leaves and a decent handful of its own roots. A single leaf with two roots will usually die. Two large divisions beat five small ones every time.
- Pot each one snugly Use a pot barely bigger than the roots, in the same free draining mix as the parent, with the crown at exactly the depth it sat before. An oversized pot stays wet and rots the cut surfaces.
The first month decides it
A fresh division has lost much of its root system and cannot support its leaves. Your whole job for four weeks is to reduce what the leaves lose while the roots regrow.
| Factor | First four weeks | Then |
|---|---|---|
| Light | Bright shade, no direct sun at all | Normal position |
| Humidity | High. A clear bag or propagator over the pot | Vent gradually over a week, then remove |
| Watering | Damp, never wet. Check every two days | Normal intervals |
| Temperature | Steady, 68 to 77F (20 to 25C) | Normal room |
| Feeding | None at all | Half strength from about six weeks |
If you bag a division, open it for a few minutes each day. Sealed and unvented, condensation sits on the leaves and fungal spotting follows within a week.
What to expect and what to worry about
Some drooping in the first week is normal and not a reason to do anything. Losing one or two of the oldest leaves in the first fortnight is also normal, and the plant is shedding what it cannot supply.
The signal you are waiting for is a new leaf, tightly rolled, pushing up from the center. Expect that four to eight weeks after division. Until it appears, resist the urge to intervene: more divisions are lost to overwatering by an anxious owner than to anything that happened during the division itself.
- All leaves collapse at once Almost always too much water in an oversized pot. Take it out, check the roots, cut away anything soft and repot into a smaller pot with fresh mix.
- Leaves go crisp and brown at the edges Too dry at the air or the root. Get the humidity up and check that the pot is not drying out completely between checks.
- Nothing happens for two months If the leaves are still firm and green, it is establishing roots and you should leave it alone. Only investigate if leaves are actively dying.
Keep a record of each division
Label every new pot with the date you divided it and how many shoots went into it. When the first new leaf appears, write that date on the same label.
Two things come out of that over a couple of years. You learn how long your conditions actually take to produce a new leaf, so you stop worrying at week five. And you learn what size of division succeeds for you, which is the single decision that determines whether a division lives or dies.