Square Corm Risers: Root a Batch of Alocasia Corms in Little Space
TL;DR
Square risers turn square cups into puddle method cups that sit edge to edge, so a whole batch of corms fits on one shelf. Each corm rests just above the water in its own cup, never touching it.
Label every cup, check the batch once a week, refresh each reservoir every 1 to 2 weeks and pot each corm when it is ready, not when the batch is.
- No gaps Square cups fill a shelf with no wasted space
- Just below the riser Water level in every cup
- Once a week A quick round of checks
- Each at its own pace Pot corms one by one
Why square for a batch
Round cups leave gaps between them and roll around on a shelf. Square cups line up edge to edge, stay put and use every centimetre. That matters in a plant cabinet or a greenhouse, where shelf space is the limit.
Each corm still gets its own cup and its own water. If one corm rots, the others are not affected.
Setting up the batch
- Prepare every corm. Rinse them clean and sort out any that feel soft. Only firm corms go in.
- Insert the risers. Place a square riser in each of its matching square cups.
- Place the corms. One per cup, growth point up, or on its side if you can’t tell.
- Fill each cup to just below the riser. No corm should touch the water.
- Label each cup. Variety and start date are enough. You will want to know which corm rooted in a week and which took longer.
- Cover and keep warm. Lids or a closed cabinet keep the humidity up. Around 22 to 26 °C.
A simple weekly routine
A batch is easiest to manage with one fixed check a week rather than constant peeking:
- Look: check each cup for new roots, shoots or soft spots.
- Top up: bring every cup back to the same level, just below the riser.
- Refresh: every 1 to 2 weeks, empty and refill each reservoir. Corms that drink fast need it sooner. This also renews the air in the cup.
- Note: write the date of the first root on the label.
When something goes wrong in a batch
What’s happening?
One corm rots
Take that cup out of the batch straight away. Cut away the soft tissue, let the corm dry for a day and restart it in a cleaned cup, away from the others. The corm troubleshooting guide covers the details.
Some root, some don’t
Completely normal: corms from the same batch wake up at different speeds. A firm corm with no roots yet is still alive. Leave it in the batch.
Cups at the edge are slower
The edges of a shelf are often cooler and darker. Rotate the cups from edge to centre during your weekly check.
Condensation everywhere
Normal with many closed cups. Wipe the lids during the weekly check, and make sure drops don’t fall on the corms.
Potting corms one by one
Every corm moves at its own pace, so pot them individually. I wait until a corm’s roots have covered its reservoir or it has 2 to 3 good leaves. Moving earlier is common, but young roots and leaves are very sensitive to humidity changes.
Use the medium you prefer: perlite, sphagnum moss, LECA, PON or a chunky aroid mix. I grow everything in PON, but perlite is the most common choice and works well. Keep new pots humid at first, then lower the humidity gradually.
Organising a large batch in a cabinet
For trays, shelf layout and labelling more than 15 corms, see the Corm Condo setup. New to corms? Start with how to do the puddle method, or read the puddle method explained.
FAQ
Do square risers fit any square cup?
No. Like all corm risers, they are made for their own container. Check the product page for the matching cups.
Can I mix varieties in one batch?
Yes. Each corm has its own cup and water, so varieties never mix. Just label them well.
Can the cups touch each other?
Yes, that is the point of the square shape. Keep enough room to lift any cup out without moving the others.
Do I need a cabinet?
No. A shelf works if each cup has its lid. A cabinet or greenhouse just makes it easier to keep a large batch warm and humid.
The Puddle Method for Alocasia Corms: Rooting Without Rot
How to Do the Puddle Method for Alocasia Corms
The Complete Guide to Acclimating Tissue-Culture
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