Gadenin日本語Get the appWhen to repot, and when to leave it alone
The right moment is just before or just as the plant wakes at the end of the hot season, when the new heads are beginning to swell but before you have started serious watering. Roots are regenerating then, so anything damaged in the move is replaced within weeks. Repot deep in the rest and the disturbed roots sit inactive for months; repot late in the growing season and you interrupt the plant exactly when it is building the heads that carry it through summer.
Repotting is not an annual chore for this plant. Every three or four years is normal, and a clump that is growing well and flowering can sit far longer than most growers expect. The reasons to act are a pot that has become solid root, a mix that has broken down into something that stays wet, a plant that has climbed above the rim on a bare woody base, or rot found at the neck that has to be cut out.
Do not repot a plant that has just been through anything else stressful. A recently purchased plant, one that was scorched, or one that has just been treated for pests should be left to settle for a full season first.
| Situation | Repot now? | Reason |
|---|---|---|
| New heads swelling, nights cooling | Yes, ideal window | Roots are regenerating and will re-establish fast |
| Deep in the hot rest | No | No root activity for months, so damage is not repaired |
| In flower | Wait until flowering finishes | Disturbance drops buds and shortens the display |
| Mix has broken down and stays damp | Yes, at the next wake-up | A slow mix is the main cause of rot in this genus |
| Rot found at the neck | Yes, immediately regardless of season | Rot spreads through a clump faster than the season matters |
| Bought within the last few months | No | Let it settle and prove itself for a season first |
The mix: grit with only a trace of organic matter
Aim for a mix that is roughly seventy to eighty percent mineral grit by volume, with the remainder a small amount of organic material for a little water retention and structure. Pumice, lava rock, coarse perlite, crushed granite and akadama-type baked clays all work; what matters is particle size in the range of an eighth to a quarter inch (3 to 6 mm) and that the material does not crumble into dust after a year.
The purpose is not dryness for its own sake. It is speed. The plant wants to be soaked and then dry within a few days, and a mix with fine particles or a lot of peat holds a wet core long after the surface looks dry. That wet core is where rot starts, and by the time you can see the damage above the grit it has already traveled through the base of the clump.
A top dressing of the same grit, a quarter to half an inch (6 to 12 mm) deep, is worth adding. It keeps the necks of the plants out of damp material, stops splash marking the bodies, and discourages fungus gnats from laying in the surface.
| Component | Rough proportion | What it does |
|---|---|---|
| Pumice or lava rock | About half | Bulk drainage with some internal water holding |
| Coarse sand or crushed granite | About a quarter | Weight and sharp drainage; keeps the mix open |
| Sieved coir or a low-peat potting soil | About a fifth | A little retention and something for roots to grip |
| Fine dust from any of the above | None | Sieve it out; dust is what turns a fast mix slow |
Sieve the whole mix over a kitchen colander before potting and throw away everything that falls through. Removing the dust does more for survival than the exact recipe you choose.
Pot choice
Conophytum root shallowly and spread sideways, so a wide, fairly shallow pot suits them better than the deep pots that suit taprooted living stones. Something two to three inches (5 to 8 cm) deep with room for the clump to expand by an inch or so on each side is about right. A pot much larger than that holds a reservoir of damp mix well beyond the roots, which is the classic route to rot.
Unglazed clay dries fastest and forgives a heavy hand with the watering can, at the cost of needing slightly more frequent soaks in the growing season. Plastic and glazed pots hold moisture longer, which is manageable if your mix is genuinely gritty and your airflow is good. Whatever you use, it needs a drainage hole; there is no version of this plant that tolerates standing water.
Doing the repot
Work with the plant and the mix both completely dry. Dry roots are brittle but clean, they release from old mix without tearing, and any small wound seals rather than sitting open in damp material. This is the opposite of the advice for most plants and it matters here.
- Turn the plant out dry Squeeze a plastic pot or tap a clay one on the bench edge and let the root ball slide out. Do not pull the clump by its heads. Support the base and let gravity do most of the work, so the woody crown is never carrying the weight of the root ball.
- Comb the old mix away Work the old material off the roots with fingers or a chopstick until you can see the root system. Remove all of it if the mix has broken down. Some fine roots will break; this is normal and they are replaced within weeks at this time of year.
- Inspect and trim Look for anything brown, mushy or hollow at the neck and cut it out with a clean blade back to firm tissue. Check for white mealybug wool among the roots. Trim dead roots off flush and leave the cuts to dry in open air for a day or two before potting.
- Pot at the right depth Set the plant so the base of the heads sits just at the surface of the mix, with the woody stem below and no part of a green body buried. Burying the heads causes rot; leaving the stem exposed leaves the plant unstable and dries the roots too fast.
- Fill, top dress and wait Trickle mix around the roots and tap the pot rather than pressing down hard, then add the grit top dressing. Do not water. Leave the plant dry in bright shade for seven to ten days so wounds seal, then begin the season's watering as normal.
The weeks afterwards, and what to record
Expect the plant to look unimpressive for two or three weeks. Slight shriveling after a repot is normal while the new fine roots establish, and the correct response is patience rather than water. Once the heads firm up again the plant has rooted, and from that point it behaves exactly as an established plant does.
Do not feed a freshly repotted plant. If you feed at all, a very dilute low-nitrogen fertilizer once or twice during the cool growing season is plenty, and it should wait until the plant is clearly growing.
Write down the repotting date, the mix you used and the pot size and material, and then note how many days that pot takes to go from soaked to bone dry in the following season. That drying time is the single most useful number you can hold about a plant like this, and it tells you far more about whether the mix is right than the look of it ever will. Also record anything you found at the roots, since mealybugs discovered at one repot are worth checking for at the next.