Gadenin日本語Get the appLeaves falling off is usually not a disease
This is the most common worry about the plant and the least often serious. Graptopetalum leaves detach at a touch, and every time you move the pot, water it, brush past it or turn it to the light, a few come away. The plant is not sick and you are not doing anything wrong.
The way to tell trouble from tidiness is to look at the leaves on the ground and the stem they came from. Dry, papery leaves from the very bottom of the stem are old age. Firm, plump leaves anywhere on the plant are mechanical damage. Yellow, translucent, wet-based leaves are rot, and only that third kind needs action.
| What you see | Likely cause | What to do |
|---|---|---|
| Plump firm leaves on the compost after moving the pot | Handling, nothing more | Nothing. Callus them and propagate |
| Dry papery leaves at the base of the stem | Normal ageing, or thirst | Check the pot weight, water if dry through |
| Yellow translucent leaves, mushy where they joined | Rot from wet compost | Stop watering, press the stem, cut above any softness |
| Black soft patch on the stem near the compost | Stem rot traveling up | Behead well above it today and re-root the top |
| White cottony fluff in the leaf joints | Mealybugs | Treat with alcohol on a swab, then check weekly |
| Pale bleached patches on sun-facing leaves | Sunburn after a sudden move | Shade it, damage is permanent on those leaves |
Rot is the one that kills
Almost every dead graptopetalum died of wet compost, usually over winter, usually indoors, usually because it was watered on a schedule while it was cold and not growing. The plant tolerates drought, heat and frost far better than it tolerates a fortnight of damp roots at 50F (10C).
Rot starts at the roots and moves up the stem, so by the time leaves near the crown look wrong the base is already gone. That is why the stem test matters: press the main stem gently at compost level with a thumbnail. Firm and woody is healthy. Any give, any sponginess, any dark seepage means act the same day.
- Take the plant out and look at the base Slide it out of the pot. Healthy stem tissue is white or pale green when cut and firm all the way. Rotted tissue is brown or black, hollow, and often smells sour.
- Cut above the damage until the cut is clean Working upward with clean snips, take slices off the stem until the exposed face shows no brown ring or dark core anywhere. If a slice still shows discoloration, you are still in infected tissue. Keep going.
- Save the top, discard the roots and the old mix Treat the clean top as a cutting. Throw away the old compost and wash the pot rather than reusing the mix, and do not try to nurse a rotted root ball back.
- Dry the cutting longer than usual Let a rot-rescue cutting callus for a full week in a dry, airy, shaded place before it goes anywhere near compost. Then plant into fresh gritty mix and wait another week before the first water.
- Salvage every sound leaf Strip the firm leaves off the discarded stem and lay them out to propagate. Even if the rescue cutting fails, a tray of leaves usually replaces the plant several times over.
Do not water a rot rescue for at least a week after potting, and do not put it in a closed propagator or cover it. Humidity is what the fungus wants. Dry air and light are what the cutting needs.
Mealybugs, the one pest worth watching for
Mealybugs are the main insect problem. They look like small specks of white cotton wool and they hide exactly where you cannot see: deep in the leaf joints, in the crown of the rosette, under the trailing stems and down among the roots. A plant with a heavy infestation stops growing and produces small, distorted new leaves.
Deal with them by touching each insect with a cotton bud dipped in rubbing alcohol, which kills on contact and dissolves the waxy coat. Work through the whole plant, then check again every week for a month, because eggs hatch in batches and one pass never finishes the job. If the plant keeps declining after clean-up, knock it out of the pot and look for white deposits on the roots; root mealybugs need the root ball washed off completely and the plant repotted into fresh mix.
Alcohol on a leaf removes the powdery bloom permanently on that spot. Accept it. The marks disappear as the plant grows new leaves, and losing the coating on a few leaves is a much smaller problem than losing the plant.
The smaller troubles
Aphids appear on flower stalks in spring rather than on the foliage. They are easy to see against the pale stalk, and a squirt of water or a wipe removes them; if the stalk is heavily colonised, cut it off, since the flowers are a minor feature of this plant anyway.
Fungus gnats mean the compost is staying damp for too long. The gnats themselves do little harm but the message is serious, because the same conditions cause root rot. Lengthen the drying interval and add more grit to the mix rather than treating the insects.
Sunburn shows as pale bleached or brown papery patches on the leaf surfaces facing the sun, always after a sudden increase in light. It does not spread and it does not heal, and the plant grows out of it over a season. Prevent it by moving a plant into stronger light over two to three weeks rather than in one step.
Slugs and snails will graze outdoor plants at night, leaving ragged bites and slime trails on the compost. Because the leaves detach so easily, the damage often looks worse than it is: they knock more leaves off than they eat. Raise the pot and check the underside of the rim.
Knowing when to give up on a plant
This is one of the few succulents where writing off the parent plant costs almost nothing. If the base has rotted, if a mealybug infestation is deep in the roots, or if the plant has been sitting wet and cold for weeks, you will spend less time taking twenty leaves and two cuttings than nursing the original.
Note the date and the circumstances when a plant fails: how long since the last water, where it was standing, what the weather had been. Rot in particular has an obvious cause once you can see the dates written down, and the same mistake in the same month next year is the one worth preventing.