It is the most common and most frustrating citrus drama: in autumn the healthy plant comes into the warm living room, and over winter it drops leaf after leaf until only a bare skeleton is left. Many blame themselves, water more or feed, and make it worse.
Yet the cause is almost always the same and easy to understand: a mismatch between warmth and light. Anyone who grasps this one principle overwinters citrus without leaf loss. This article explains it.
Why the leaves fall
Citrus is evergreen and normally keeps its leaves all year. In winter, though, it comes down to the balance of warmth and light. If it is warm, the plant's metabolism runs at full tilt, it wants to grow and breathe. For that it needs light, to gain energy through the leaves.
If it now stands warm but dark, it uses more than it can produce from the few winter sun hours. The plant slips into deficit and drops leaves to save consumption. That is exactly what happens in the warm living room with its winter light far too weak for citrus.
The two ways that work
There are two coherent combinations of warmth and light, and one that fails.
Bringing warmth and light into balance
- Cool and bright (ideal)
At 5 to 10 degrees citrus rests, its metabolism is shut down and it needs little light. A bright, cool room is the best winter quarters.
- Warm and very bright (fallback)
If the plant must stand warm, it needs a great deal of light, often only achievable with a plant lamp. Laborious but possible if there is no cool room.
- Warm and dark (the mistake)
The most common and worst combination. Here the citrus reliably drops its leaves. That is exactly what happens in the warm home.
- Cool and dark (borderline)
Works at a pinch, because in the cold little light is needed. A bit more brightness is always better, though. Frost-free it must remain in any case.
Care in the winter quarters
Bring it in cool and bright
Bring the citrus to its brightest cool spot before the first frost, ideally at 5 to 10 degrees. A bright conservatory, a cool stairwell or a cellar with a window.
Water sparingly
In the cool rest the plant needs little water. Water only when the soil has dried on top, and avoid waterlogging. Wet, cold roots rot.
Do not feed
There is no feeding in winter. The plant rests and would only put the nutrients into weak, pale growth.
Watch for pests
Dry heated air attracts scale insects and spider mites. Check the leaf undersides regularly. More on ongoing care in Caring for citrus plants in pots.
Bring it out slowly
From spring the citrus may go back outside, but at first to a part-shaded, sheltered spot. Otherwise the leaves, grown sensitive in the winter light, scorch in the full spring sun.
The warmer, the brighter. Leaf drop is not a care mistake but a light-warmth mismatch. Overwintered cool and bright, citrus keeps its leaves.
The core rule for overwintering citrus
Frequently asked questions
Why does my lemon lose all its leaves in winter?
Because it stands too warm and too dark. In warmth the plant uses a lot of energy that it cannot produce in the weak winter light. It drops leaves to save consumption. Setting it cooler and brighter fixes it.
How warm may citrus stand in winter?
Best cool at 5 to 10 degrees, then it rests and needs little light. Warm works only with a great deal of light, often only with a plant lamp. Warm and dark is the combination that leads to leaf drop.
Can a bare citrus recover?
Usually yes. Set it cooler and brighter, water sparingly and do not feed. As long as the shoots have not dried out, the plant normally re-sprouts in spring. Patience is needed.
How often do I water citrus in the winter quarters?
Only a little. In the cool rest hardly any water evaporates. Water only when the top soil has dried, and never leave water in the saucer, or the roots rot.
When may the citrus go back outside?
From spring, when no more frosts threaten. Get it used to the sun slowly, at first part-shaded and sheltered. Placed straight into full sun, the leaves grown sensitive over winter scorch.
