Gadenin日本語Get the appTwo normal events that look like disasters
Before treating anything, rule out the two things this plant does on purpose. The first is the summer rest. As sustained heat arrives the rosettes fold inward into tight buds resembling green artichokes, the lower leaves go papery and drop in numbers, and the plant stops growing entirely for weeks. Every one of those signs reads as a dying plant and none of them is. The correct response is less water, not more, and the rosettes reopen on their own when nights cool.
The second is flowering. An aeonium rosette flowers once, and the rosette that flowers dies afterwards. It stretches upward into a long cone, opens a tall pyramid of small starry yellow or cream flowers over several weeks, then browns and collapses. Nothing can stop it and nothing caused it. On a branched plant the other heads carry on unaffected, which is why keeping a plant branched matters. On a single-headed plant, the flowering spells the end unless you have already rooted a cutting.
Tell the two apart by direction and season. The summer rest closes rosettes downward and inward with the growing point staying firm. Flowering pushes one rosette upward into a spike, in spring, and affects only that head.
Mealybug, the most persistent pest
Mealybugs are the pest you will meet most often, and the tightly packed center of an aeonium rosette is an ideal hiding place. They appear as small white waxy specks or cottony fluff wedged where the leaves join the stem, and they are often found alongside sticky residue and sooty mold. Growth slows, new leaves come through distorted, and an infested plant looks generally dull. There is also a root form that lives in the mix and shows as white powdery deposits on the root ball at repotting.
Deal with them early and mechanically. Dab visible insects with a cotton bud dipped in rubbing alcohol, which kills on contact, and repeat weekly for a month because the eggs hatch in waves. Wash the rosette out with a firm jet of water where the plant is sturdy enough. For root mealybug, bare-root the plant, wash the roots clean, discard all the old mix and repot into fresh. Isolate any infested plant from the rest of your collection until you have had two clean inspections a fortnight apart.
Rot, and cutting above it in time
Rot in an aeonium starts at the base of the stem far more often than in the leaves, and the cause is nearly always water around inactive roots: a heavy watering during the summer rest, a pot standing in run-off, or a mix that has broken down and no longer drains. The early sign is a stem that has lost its hardness low down, sometimes with a darker sunken patch, and leaves that drop from all over the plant rather than only from the lowest ring.
There is no treatment for rotted tissue, but the plant is usually saveable because the head is independent of the base. Cut the stem across, well above the soft area, and look at the cut face. Clean pale tissue means you are above the damage. Any brown ring or streak means cut higher and look again. Once the face is clean, dry the cutting for several days and reroot it. Discard the rotted base and all of its mix, and do not reuse the pot without washing it.
Crown rot is the other version, and it comes from water sitting in the center of a rosette through cool still weather. The growing point goes brown and mushy and the inner leaves pull away wet. On a branched plant, cut that head off and the rest continues. Prevent it by watering the mix rather than the rosette and by keeping the plant somewhere with air movement.
The full symptom list
Almost everything that appears on an aeonium falls into a short list, and the correct response is usually environmental rather than chemical.
| What you see | Likely cause | What to do |
|---|---|---|
| Rosettes close into tight buds, lower leaves shed | Normal summer rest | Cut watering right back and leave the plant alone |
| One rosette stretches into a tall cone and flowers | That rosette is monocarpic and will die | Take cuttings from other heads, cut the spent stem out afterwards |
| White cottony specks in the leaf joints | Mealybug | Alcohol on a cotton bud weekly for a month, isolate the plant |
| Stem soft and dark at the base, leaves dropping everywhere | Stem rot from water around inactive roots | Cut the head off above clean tissue, dry it and reroot |
| Growing point brown and mushy after a cool wet spell | Crown rot from water in the rosette | Remove that head, water the mix not the plant, improve airflow |
| Plant lifts out with no roots, base hollowed | Vine weevil grubs in the mix | Destroy grubs, discard all old mix, reroot the head in fresh mix |
| Dry bleached patches on upper leaf surfaces | Sun scorch, usually after a sudden move | Shade in the afternoon, acclimatize moves over two weeks |
| Long bare stem with a small pale rosette on top | Not enough light | Behead and reroot, then grow the new plant in full sun |
| Leaves translucent then collapsed after a cold night | Frost damage | No recovery for damaged tissue, cut back to firm growth and keep above 40F (4C) |
Prevention, and a loss log worth keeping
Nearly every row above is prevented by the same handful of habits: a mix that drains in seconds, water only while the plant is actively growing, air moving around the rosettes, full light in the cool months, and no frost. Add one more that is specific to this genus, which is keeping every plant branched or keeping a rooted spare, so that a flowering rosette is a loss of one head rather than of the plant.
Rather than logging treatments, log losses. For each head you lose, note the date, the plant, and which pattern it matched: rested and reopened, flowered and died, went soft at the base, or collapsed after a cold night. One year of that list is unambiguous. If most losses are soft stems in the same summer fortnight, the fix is your watering calendar. If they cluster after one cold night in late autumn, the fix is bringing plants in a week earlier.