Gadenin日本語Get the appFind the problem from what you can see
Haworthia has a short list of real problems, and the symptoms overlap enough that people treat the wrong one. Work from where on the plant the change appears rather than from the color alone: the base, the leaf surface, the leaf tips and the compost surface each point to a different cause.
| What you see | Most likely cause | How urgent |
|---|---|---|
| Lower leaves soft, translucent, browning at the base | Crown or root rot from overwatering | Act today |
| White cottony specks between the leaves | Mealybug | Act this week |
| Plant loose in its pot, white specks on the roots | Root mealybug | Act this week, unpot to confirm |
| Hard brown discs stuck to the leaf surface | Scale insect | Act this week |
| Dry pale patches on the sun-facing side | Sun scorch | Move it, damage will not heal |
| Rosette opening out flat, leaves pale and long | Too little light | Move it, new leaves will come tighter |
| Small flies rising off the compost | Fungus gnats from compost kept too wet | A nuisance, not a threat |
| Fine webbing and dull stippled leaves | Spider mite in hot dry air | Act this week |
Rot: the one that kills
Rot is the cause of death for the overwhelming majority of haworthias, and it almost always follows water given to a plant that was not growing, either during the summer rest or in a cold room in winter. It starts at the base where the leaves join the stem, spreads upward through the rosette, and moves fast enough that a plant which looked fine on a Monday can be beyond saving by the weekend.
The early sign is a lower leaf that has gone slightly translucent and pulls away with almost no resistance, leaving a wet, brown mark at the base. Do not wait to see whether it spreads. It spreads.
- Unpot immediately and wash the roots clear Get the plant out of the wet compost the same day. Rinse the roots under a tap so you can see the base of the stem clearly rather than guessing through clinging compost.
- Cut back until the tissue is clean Slice upward through the stem in thin sections with a clean blade until the cut face is uniformly pale with no brown ring or flecks. Wipe the blade between cuts or you carry the rot upward with you.
- Remove every affected leaf Pull off all leaves that are soft or discolored at the base, even ones that look fine at the tip. A single infected leaf left in place restarts the whole thing.
- Dry the cut face for a week Stand the remaining head of the plant in bright shade, out of any pot, until the cut is hard and dry to the touch. This is longer than feels reasonable and it is what makes the difference.
- Root the head in dry gritty mix Set it on the surface of dry gritty potting mix so the cut face just touches, in bright shade at around 68F (20C). Give no water until roots appear, which takes four to eight weeks.
If the rot has already reached the growing point at the very center of the rosette, the plant cannot be saved. Take healthy outer leaves as cuttings and any offsets that are still firm, and discard the rest with the compost.
Mealybug, above and below the compost
Mealybug is the pest haworthia actually gets, and the tight rosette gives it perfect cover. Look for small white cottony specks wedged in the deep angles where the leaves meet the stem, usually on the shaded side. On the leaf surface they are easy to see and easy to remove; down in the crown they persist for months if you only treat what is visible.
Root mealybug is the version people miss. The plant loses vigor, sits loose in its pot and stops producing new leaves, with nothing wrong above the compost at all. Unpot any plant that declines for no visible reason and look for white powdery deposits on the roots and against the inside wall of the pot.
Treatment is the same in principle for both: physical removal first, then a systemic follow-up. For a light infestation on the leaves, a cotton bud dipped in rubbing alcohol touched onto each insect kills it on contact, and repeating every five days for three rounds clears the eggs that hatch after the first pass. For root mealybug, wash all the compost off, cut away badly infested roots, soak the root system in an insecticidal solution suitable for houseplants, and repot into fresh compost in a clean pot. Never reuse the old compost or the old pot without scrubbing it.
| Treatment | Where it works | How to apply |
|---|---|---|
| Rubbing alcohol on a cotton bud | Visible insects on leaves and in the crown | Touch each insect directly, repeat every 5 days, 3 times |
| Insecticidal soap spray | Light infestations across the whole plant | Spray to run-off in shade, never in sun. Repeat weekly |
| Systemic granules in the compost | Repeat infestations and root mealybug | Apply in a growing season, water in, follow the label |
| Bare-rooting and repotting | Root mealybug | Wash roots clean, new compost, new or scrubbed pot |
Damage from light and heat
Sun scorch appears as dry, pale, papery patches on the surfaces facing the window, often after a single bright day following a spell of dull weather. The plant does not repair them; the marked leaves carry the scars for the several years they live, and the plant only grows out of it as new leaves replace the old. Move it into bright shade and accept the appearance for a year.
Red or bronze coloring across the whole leaf is a different thing and is not damage. It is a stress response to strong light and heat, and it drains back to green within a month in shade. In moderation it does no harm at all, and some growers deliberately produce it.
Heat damage without sun is possible on a windowsill in summer, where trapped air behind a curtain can reach far higher temperatures than the room. If the leaves closest to the glass go soft and translucent in hot weather while the rest of the plant is fine, that is heat, and the answer is to move the pot rather than to add shade.
Minor pests and the record that prevents repeats
Fungus gnats mean the compost surface has been kept damp too long. They do not damage a healthy haworthia, but their presence is a reliable warning that the watering interval is too short. Let the pot dry fully, top-dress with a half-inch (1 cm) layer of coarse grit, and they disappear within a couple of weeks. Spider mite is rare and turns up only in hot, dry, still air, showing as a dull stippled leaf surface with fine webbing in the crown; improved air movement plus a soap spray deals with it.
Whenever you find a pest or a rot, write down the date, which plant, and what the conditions had been for the two weeks before. Almost every outbreak traces back to something specific: a plant watered during a heatwave, a new plant brought in without a quarantine period, a pot moved into a corner with no air movement. One line at the time turns each incident into something you can avoid next year rather than a run of bad luck.
Keep any new haworthia separate from your others for three weeks and inspect the crown and the compost surface twice in that time. Mealybug arrives on new plants far more often than it appears from nowhere.