Plant records · Direct sun
Aloe vera: the plant that rots because it is treated like a houseplant
Aloe vera is a desert plant that people keep indoors and water like a fern. It needs more light than any window in a northern-facing room can give, and it wants to dry out completely between waterings — including a near-total drought in winter. Almost every Aloe problem is one of those two things.
Aloe vera · Asphodelaceae
| Botanical name | Aloe veraAsphodelaceae |
|---|---|
| Light | 3,000-10,000 lxDirect sun |
| Humidity | 20-40% |
| Watering | Every 20 days |
| Drainage | Very gritty: 40% cactus compost, 30% perlite, 30% coarse grit or pumice. Water should pass through the pot in under two seconds. |
| Mature height | 60 cm |
| Growth rate | Slow: three to six new leaves per year. The plant also produces offsets (pups) freely from the base, more in good light. |
| Propagation | Separate offsets from the base with a clean knife when they are at least 8 cm tall, and let the wound callus for two days before potting into dry gritty mix. |
| Pet safety | toxicThe latex under the leaf skin — the yellow sap, not the clear gel — is a strong purgative and causes vomiting and diarrhoea in cats and dogs. The clear inner gel is not the problem. |
presentationWhat you are seeing
- Leaves that go flat, spread outward and lose their upright shape, becoming thin and curling at the tips.
- The base of the plant turning brown and soft, with leaves detaching easily, while the leaf tips are still green.
- Leaves that turn reddish-brown or purple, especially on the upper surface facing the window.
aetiologyWhy it happens
- Flat, spreading, curling leaves mean insufficient light. The upright growth of Aloe is a light-driven response: without strong light, the leaves grow longer and weaker to expose more surface, and they can no longer support themselves.
- Soft brown bases are rot, and rot in Aloe is caused by winter watering. Aloe has no mechanism for dealing with water when it is cold and not growing. A single winter watering of a plant at 12 C can kill it.
- Red or purple leaves are a stress pigment response to high light — mild sun stress. It is not damage and often indicates the plant is finally getting enough light. It becomes a problem only if the leaf also bleaches and the surface goes papery, which is sunburn.
managementWhat to do
- Give it direct sun: a south-facing windowsill with four or more hours of direct sun, or outdoors in full sun from May to September once acclimated. This is not a plant that will grow on an east windowsill through a British winter.
- Water thoroughly and then leave it completely alone until the mix is dry to the bottom of the pot. For a 15 cm pot in gritty mix that is roughly every 20 days in summer.
- Stop watering almost entirely from November to March. Once every six to eight weeks is enough for a plant in a cool room, and if the room is below 12 C, none at all.
- Never water into the centre of the rosette. Water around the rim and keep the growing point dry, especially in winter.
- For rot: unpot, cut away all brown and soft tissue with a clean knife until you reach firm pale green, dust with sulphur, and leave the plant bare-root in a dry place for a week before repotting into dry gritty mix. Do not water for two weeks after.
What full sun actually requires indoors
Aloe vera at 10,000 lx is a compact plant with thick, upright, grey-green leaves. The same plant at 800 lx — a north windowsill — produces thin, long, floppy leaves that splay outward and never stand up.
The best indoor position in most homes is a south or south-west windowsill where the plant gets four to six hours of direct sun. A west windowsill works in summer. An east windowsill gives two to three hours and is marginal. A north windowsill will not grow it.
If you have no sunny windowsill, a grow light on for twelve hours a day at 20-30 cm will produce a compact plant. This is one of the few houseplants where a grow light makes an obvious, immediate difference.
- South windowsill, 4-6 h direct: ideal
- West windowsill, summer: good
- East windowsill, 2-3 h: marginal, plant will stretch
- North windowsill: will not work
- Grow light at 25 cm, 12 h/day: 5,000-10,000 lx, works well
The winter drought, and why it is not optional
Aloe vera grows actively in warm weather and goes almost dormant in cool, short-day conditions. During dormancy it has no capacity to take up and use water, so water in the pot simply sits against the roots.
The practical routine: from November to March, water once every six to eight weeks if the room is warm, and not at all if the room is below 12 C. A plant kept on a cool windowsill over winter can go four months without water and lose nothing.
The sign that you have got it right is a plant that starts growing strongly in April with no soft patches at the base. The sign that you have got it wrong is a plant that collapses in February.
Harvesting a leaf without harming the plant
Taking a leaf for the gel is fine if you take the right one. Choose the outermost, lowest leaf that has fully thickened — those are the oldest and the plant can spare them. Do not take leaves from the centre of the rosette, which are the growing leaves.
Cut close to the base with a clean knife and let the cut surface drain for ten minutes: the yellow latex that runs out first is the irritating part and should be rinsed away. The clear gel inside the leaf is the useful part. A plant with fewer than eight leaves should not be harvested at all.
Sheets that reference this plant
| Crispy brown tips | Brown leaf tips look identical whatever caused them, which is why so many people treat the wrong thing for years. In practice there are four causes… |
|---|---|
| Spots and blotches on leaves | Leaf spots are the symptom most often misdiagnosed as disease when they are caused by water, sun or the plant's own physiology. The decision path is… |
| Pale or white new growth | New growth coming through pale is either a light problem or a nutrient problem, and the two look nothing alike once you know the pattern. Etiolation… |
Troubleshooting
My aloe is falling over and the leaves are flat. Is it dying?
Should I cut the pups off?
Can I use the gel straight from the leaf on my skin?
CaveatCare information only. Not medical advice. The leaf latex is toxic to cats and dogs if eaten — contact a veterinarian or poison control centre rather than relying on this page.
Published2026-10-12 ·