Gadenin日本語Get the appWhen to do it, and when not to
There is one good window and several bad ones. The good window opens in spring once the old leaf pair has finished drying to paper and the new pair is fully exposed and firm, and it opens again in late summer just before the plant wakes for its autumn growing season. In both cases the plant is between jobs and can afford to rebuild roots.
The bad windows are everything else, and one of them is genuinely dangerous. Never repot during the leaf change. The plant has committed its entire reserve to building the new pair, has minimal working root, and disturbing it then either stalls the change or leaves you with a plant that never plumps properly that year. Repotting in deep summer dormancy is also poor practice, because damaged roots sitting in heat will not heal and the plant is not growing enough to replace them.
How often is a separate question from when. Lithops are slow and are perfectly happy in the same pot for three to five years. Repot when the clump has outgrown the pot, when the mix has broken down and started holding moisture, when you suspect root mealybug, or when you inherited a plant in ordinary potting mix, which is the most common reason of all.
| Situation | Repot now | Reason |
|---|---|---|
| Old leaves fully papery, new pair firm | Yes, the best moment | Plant is between growth phases and roots regenerate quickly |
| New pair just appearing in the slit | No, wait | The leaf change runs on stored reserves and must not be interrupted |
| Midsummer, plant flat and resting | Only if rot is suspected | Root damage will not heal in dormancy |
| Newly bought in peat-based compost | Yes, at the next safe window | Peat holds water for weeks and will rot the plant eventually |
| Body soft, base browning | Yes, immediately, whatever the season | This is rot and waiting for a better date loses the plant |
The mix: think grit with a trace of soil
The mix that works is not a succulent compost with some perlite stirred in. Aim for seventy to eighty percent mineral material by volume and only a small fraction of organic matter, and some experienced growers run a mix that is purely mineral and feed lightly instead. What you want is something that wets right through in seconds, drains in seconds, and is bone dry again within three or four days in warm weather.
Suitable mineral components are pumice, coarse perlite, decomposed granite, crushed lava, coarse quartz sand and akadama-type fired clay. Particle size matters as much as material: aim for pieces around one to four millimeters, and sieve out the dust, which is what turns a fast mix into a slow one. The organic fraction, if you use one, should be a small quantity of coir or sieved bark rather than peat.
| Component | Proportion | What it does |
|---|---|---|
| Pumice or coarse perlite | About one third | Holds air, gives the roots something to grip |
| Coarse sand or fine gravel | About one third | Weight and sharp drainage |
| Fired clay or crushed lava | About one fifth | Holds a trace of moisture and nutrient without staying wet |
| Sieved coir or bark fines | One fifth or less | A small nutrient reserve; leave out entirely if you feed |
| Top dressing of grit | A layer half an inch deep | Keeps the neck of the plant dry and stops splashing |
Skip the layer of gravel at the bottom of the pot. It does not improve drainage, it raises the level of the saturated zone, and in a small pot it wastes the depth the taproot needs.
Pot choice: deeper than you would guess
A lithops body may be an inch across but the root system below it is a proper taproot with fine feeder roots along its length, and it wants room to go down. A pot four to five inches (10 to 13 cm) deep suits a single adult plant or a small clump. Wide shallow bowls, which look right for something that resembles a pebble, force the taproot to curl and leave the plant unstable and prone to drying out at exactly the wrong moment.
Width should be modest. A pot barely larger than the plant or clump means the mix dries quickly, which is what you want. Unglazed terracotta dries fastest and forgives watering mistakes. Plastic and glazed ceramic hold moisture longer and demand more discipline, though they are fine in a hot dry climate. Drainage holes are non-negotiable, and a pot without them is not a pot for this plant at any price.
Doing the repot
Work with the plant completely dry, both the mix and the roots. Dry roots are flexible and shed old grit cleanly, whereas wet roots tear and the wounds sit damp. Have the new pot filled and ready before you lift the plant so that it spends as little time out of the ground as possible.
- Tip the plant out rather than pulling it Squeeze a plastic pot or tap the rim of a terracotta one and let the whole root ball slide out into your hand. Pulling on the body itself can separate it from the taproot, which is not recoverable.
- Crumble away the old mix and look at the roots Work the grit off with your fingers until the taproot and the fine roots are visible. Healthy roots are firm and pale to tan. Look for white cottony patches, which are root mealybug, and for black mushy sections, which are rot.
- Trim only what is dead Cut away black or hollow roots with clean scissors and leave the rest. Do not shorten a healthy taproot to fit a shallow pot; find a deeper pot instead. If you cut anything, let the plant sit dry in open air for two or three days before potting so the cuts callus.
- Set the plant at the right depth Hold it so the neck, where the leaves meet the root, sits at the level of the mix surface, then fill around it and settle the grit by tapping the pot. Bodies buried too deep rot at the neck. Bodies set too high dry out and lean.
- Top dress and leave it dry Add half an inch of coarse grit around the plant so no organic material touches the skin. Then put the pot back in its usual light and give it no water for two weeks, or three if you trimmed roots.
The weeks afterwards, and what to record
A repotted lithops does nothing visible for a while and that is the correct outcome. The first sign it has taken hold is the body firming up and regaining gloss after the first watering, usually two to four weeks after potting. Slight shrinkage in the meantime is expected. If the plant is still soft a month after its first post-repot watering, tip it out and look at the roots again rather than watering more.
Write down the date of the repot, the mix you used and in what proportions, the pot size and material, and what the roots looked like when you took the plant out. Note how many days you waited before the first watering. Because repotting happens once every few years, memory is worthless here, and the note about root condition is the one that tells you next time whether your mix and your watering are actually working or merely not yet failing.