An aloe turns yellow for five reasons, and the feel of the leaf sorts them out. Soft, translucent yellow starting at the base of the leaves, with wet soil, is rot from overwatering, the most common cause. Firm leaves gone pale yellow or orange on the side facing a window, soon after a move into brighter light, is sun stress. Firm leaves slowly paling and thinning over months in a dim spot is too little light. Yellow and mushy after a cold night is chilling. And a plant that has filled its pot solid, with yellowing outer leaves and water running straight through, is pot-bound.
Press the yellow leaf between finger and thumb. Soft means water. Firm means light, cold or the pot.
What the leaf tells you
| What you see | Most likely cause | Check this first |
|---|---|---|
| Lower leaves yellow, translucent and soft at the base, sagging, soil wet, sour smell | Overwatering and root rot | Squeeze the leaf base; root check |
| Firm leaves pale yellow or orange on the side facing the window, after a move or in summer | Sun stress | Recent change of position; hours of direct sun |
| Firm leaves slowly paler, thinner and flatter over months in a dim room, leaning toward the light | Too little light | Distance from a window |
| Yellow and mushy patches after a cold night near glass, soil not necessarily wet | Cold damage | Where the plant sat |
| Outer leaves yellowing, roots out of the drainage hole, water runs straight through | Pot-bound | Slide the plant out |
| One outer, oldest leaf yellowing and drying while the rest are firm | Natural aging | Nothing else changed |
Overwatering and root rot
Aloe stores water in its leaves and needs its soil to dry out completely between waterings. In soil that stays wet the roots rot, and then the base of the leaves, and the plant can no longer hold its stored water in place. The lower leaves go yellow and translucent from the base, feel soft or watery, sag outward, and may split. The soil is wet days after watering and smells sour.
What to do: slide the plant out. Healthy aloe roots are pale and firm; rotted ones are brown, soft and few. Cut away all soft roots and any leaf that is soft at the base, back to firm tissue, with a clean knife. Let the plant sit out of soil in a dry shaded place for two or three days so the cuts callus. Repot in a gritty cactus mix in a pot with drainage, no larger than the roots need, and do not water for a week or two. Then water thoroughly and let the soil dry completely, which in most rooms means every three to five weeks.
A plant with no firm roots left can still be saved: let the base callus for several days and set it on dry gritty mix; roots form over a few weeks. Firm side pups can be separated and potted on their own.
Sun stress
Aloe likes bright light, but an aloe moved suddenly from a shop or a dim corner into hours of direct sun turns pale yellow, orange or reddish on the side facing the light within days. The leaves stay firm. This is a stress response rather than damage, though hot glass can scorch brown patches as well.
What to do: pull the plant back from the glass or filter the light for a few weeks, then move it closer gradually. The colour returns to grey-green over weeks once the plant has adjusted or the light has eased.
Too little light
In a dim room an aloe slowly loses colour, its leaves grow long, thin and flat instead of thick and upright, and the whole plant leans toward the nearest window. The change takes months.
What to do: move to a bright window with some direct sun, gradually. New leaves come in firm and green; old thin ones stay as they are.
Cold damage
Below about 10 degrees Celsius an aloe's leaves go yellow and mushy in patches, often where they touched cold glass, within a day or two of a cold night. What to do: move the plant away from cold windows in winter. Mushy patches are lost; cut back damaged leaves to firm tissue and let the cuts dry.
Pot-bound
A happy aloe fills its pot with roots and pups within a couple of years. Once the pot is solid, water runs straight through, the plant dries within days, and the outer leaves yellow and thin. Roots push out of the drainage hole. What to do: repot one size up in gritty mix, or divide off the pups into their own pots.
Natural aging
The oldest, outermost leaf yellows, dries and shrivels as the plant makes new leaves in the centre. If the rest is firm and green, nothing is wrong. What to do: pull or cut the dead leaf at the base.
The squeeze and root check
Squeeze the base of the yellow leaf: firm rules out rot. If it is soft, or if the soil is wet regardless, slide the plant out and look at the roots: pale and firm is fine, brown and soft is rot. Aloe comes out of its pot easily and does not mind the disturbance.
What to do today, by cause
- Overwatering: unpot, cut away soft roots and leaves, let callus, repot in gritty mix, wait before watering.
- Sun stress: pull back from the glass for a few weeks, then move closer gradually.
- Too little light: move to a bright window gradually.
- Cold: move away from cold glass, trim mushy parts.
- Pot-bound: repot one size up or divide.
- Natural aging: remove the dead leaf.
Frequently asked questions
Can a yellow aloe turn green again?
Yellow from sun stress fades back to grey-green over weeks once the light eases or the plant adjusts. Yellow from rot does not recover; the soft tissue must be cut away. Yellow from low light stays on the old leaves, and the new leaves come in green once the light improves.
Why is my aloe turning yellow and soft?
Because the roots have rotted in wet soil and the base of the leaves is rotting with them. Unpot, cut away everything soft, let the cuts dry for a few days, repot in gritty mix and do not water for a week or two.
Why is my aloe turning yellow after moving it?
Because it was moved into much brighter light than it was used to and has coloured up in response, or, if the new spot is dim, because it is beginning to stretch. Firm pale yellow on the sunny side is sun stress; pull it back a little and reintroduce the sun gradually.
How often should I water an aloe?
Only when the soil is completely dry, thoroughly, and then not again until it is completely dry, which in most rooms is every three to five weeks and less in winter. A firm plump aloe is never thirsty; a wrinkled thin one is.