Leaves falling off
A plant dropping leaves is usually reacting to a change rather than to a disease. What it is adjusting to, and when the dropping is a warning instead.
What it usually is
1 A move, or a change in the room
| How to tell | The dropping began within a fortnight of the plant arriving, being moved, or the heating going on. It is often worst on figs, which are famous for it. The leaves that fall are green rather than yellow. |
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| The fix | Leave it exactly where it is and change nothing else. A plant adjusting to new light will shed what it cannot support and then stop. Moving it again restarts the process. Water on the soil's terms rather than the calendar's while it settles. |
2 A cold draught, or a hot one
| How to tell | The plant sits near a door that opens to the outside, a single glazed window, or an air vent or radiator. Dropping is worse on the side facing it, and there may be dark patches on the leaves that fell. |
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| The fix | Move it a metre away from the source. Cold draughts and hot dry blasts do the same thing by different routes, and both show as sudden leaf loss rather than gradual yellowing. |
3 Watering, at either extreme
| How to tell | Compost that is sodden, or compost that has shrunk from the pot's sides. Both cause leaf loss, and both look like each other from above, which is why the finger test matters. |
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| The fix | For a sodden pot, let it dry to the top third and empty the saucer every time. For a bone dry pot, soak it in a bowl for twenty minutes so the compost swells back to the sides, then drain it. |
Through the year. Autumn leaf drop on a plant near a window is often just the light going. A plant that drops in the first fortnight of the heating season is reacting to warm dry air rather than to anything you did.
A plant that drops leaves is nearly always adjusting rather than dying. It has been growing at a size that suited one set of conditions and has arrived in another, and the fastest way to balance its books is to shed the leaves it can no longer pay for. This is why a new plant sheds in its first month, why a plant moved from one room to another sheds for a fortnight, and why almost every fig sheds a handful of leaves in October.
The single most useful response is to do nothing except keep the watering honest. The instinct to help, by feeding, by repotting, by moving it somewhere else, is what turns a two week adjustment into a two month decline. A plant settling into new light needs the light to stay the same long enough to settle into.
There are three exceptions worth separating out.
If the leaves that fall are limp and the compost is wet, this is not adjustment, it is the beginning of root trouble, and the entry on a soft mushy base is the one to read. Check the roots before you decide.
If the plant sits near a door to the outside, or over a radiator, or under an air conditioning vent, the draught is the cause and no amount of patience fixes it. Cold air makes a plant close its pores and drop; hot dry air pulls moisture out faster than the roots can supply. A metre of distance usually solves both.
And if the dropping continues past a month, with nothing changed and the watering right, look for a pest on the undersides of the remaining leaves. Scale, mealybug and spider mite all cause slow leaf loss, and all three are easy to miss until you turn a leaf over.
One last thing about figs, since they are the plants people write about. A weeping fig will drop a third of its leaves after a move and grow them back over two months if left alone in good light. That is normal for the species and not a sign you have failed it.
Entries that name it
What the journal says about this symptom on each plant.
| African milk tree | The small leaves along the ridges dropping in autumn, which is normal. Nothing to do. They come back in spring. If it happens in midsummer, check the light and the watering. |
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| Alocasia | A cold or dry winter, which sends it into dormancy. Water far less, keep it warm, and wait. The tuber is alive and it regrows in spring. |
| Asparagus fern | A dry spell or a move, which brings down a shower of the fine green needles. Water more evenly. It regrows quickly from the base, so cut out anything that has gone brown. |
| Baby rubber plant | A cold draught, or compost that dried out completely. Keep it above 13 degrees and water before the pot is bone dry. |
| Boston fern | A move, a draught, or a swing in humidity. Settle it in one humid spot away from doors and heaters. Shedding after a move is normal and stops once conditions steady. |
| Bougainvillea | Cold, a draught, or the shock of being moved indoors for winter. Expect some drop and do not respond by watering. Keep it barely moist and frost free through winter and it will releaf in spring. |
| Burro's tail | Being touched, which is the whole difficulty with this plant. Hang it where nothing brushes past. Every fallen leaf will root if laid on gritty compost, so keep them. |
| Chilli and sweet pepper | A sudden drop in temperature, or a plant that dried out. Keep it above twelve degrees and water evenly. Peppers shed leaves and flowers at the first cold night. |
| Christmas cactus | Buds dropping after being moved, or after a change in light, temperature or watering. Once buds have formed, leave the plant exactly where it is and keep the watering steady until the flowers are over. |
| Creeping fig | A cold draught, or a sudden change of position. Keep it above ten degrees and away from doors. It regrows from the stems once settled. |
| Croton | Any sudden change, most often the move home from the shop, a draught, or a cold night. Settle it in one warm bright draught free spot and leave it there. A plant that has dropped everything usually releafs within two months if it is kept warm and lightly moist. |
| Crown of thorns | A dry spell or a cold snap, and the leaves come back. It sheds leaves under stress and keeps flowering regardless. Water a little more consistently and keep it above ten degrees. |
| Fiddle-leaf fig | A sudden change, most often a move, a draught, or a swing in temperature. Settle it in one place with steady light and warmth and leave it there. New leaves come once conditions stop changing. |
| Garden privet | A hard winter. Privet is only semi-evergreen to evergreen depending on how cold it gets, and a severe cold snap sheds more leaves than a mild one would. Leave it alone. The spring flush replaces what was lost within a few weeks, and only a bare patch that is still empty well into the growing season is worth investigating further. |
| Ginseng ficus | A move, a draught or a change in light, which every ficus answers this way. Put it somewhere bright and steady and leave it alone. It will releaf within a month from bare wood. |
| Golden dewdrop | A cold snap, since this is a frost-tender plant. Foliage can turn purple or nearly black before it drops. In a marginal climate, expect this most winters and let it regrow from the base once the weather warms rather than assuming the plant has died outright. |
| Grape ivy | A cold draught or a sudden move. Keep it above twelve degrees and away from a door. It regrows quickly once settled. |
| Jade plant | Overwatering, or a sudden cold draught. Check the compost. Damp means water far less; a plump leaf that falls at a touch is nearly always too much water rather than too little. |
| Lemon | A move, a cold draught, or wet compost. Keep it somewhere steady, above five degrees, and let the compost dry between waterings. Citrus drop leaves at every change. |
| Maidenhair fern | Dry air in a heated room, which is the same problem earlier. Move it to a bathroom or put it in a closed glass container. Misting a maidenhair does almost nothing. |
| Ming aralia | A move, a draught or a change of light, all of which it takes badly. Put it somewhere steady and leave it. It sheds leaves at any disturbance and takes weeks to settle, which is normal for this plant. |
| Money tree | A move, a draught, or a swing between soaked and bone dry. Settle it somewhere steady and water on a rhythm. It releafs readily from bare stems. |
| Norfolk Island pine | A dry spell, and the lost branches do not come back. Water on a steadier rhythm. This is the plant to remember when someone says a houseplant always recovers. |
| Polka dot begonia | A cold draught, or compost that swung from dry to soaked. Keep it above fifteen degrees and away from a door, and water on a steadier rhythm. |
| Purple shamrock | Dormancy, which is normal, or heat and drought bringing it on early. Cut the old growth off, keep the pot barely moist and cool for a few weeks, then water again and it regrows. |
| Rubber plant | Cold, a draught, or a sudden move to a darker room. Keep it above about 12 degrees, away from doors and winter windows, and settle it in one spot with steady light. |
| String of pearls | A sharp change in watering, or cold. Keep the rhythm steady and the room above 10 degrees. Beads dropping in handfuls after a very wet spell mean rot rather than thirst. |
| Umbrella plant | A move, a draught, or compost that went from soaked to bone dry. Settle it somewhere steady and water on a rhythm. It sheds leaves at any sudden change and regrows within weeks. |
| Weeping fig | Any change at all, and most often a move to a new position, a draught or a cold night. Choose one bright draught free spot and leave it there. A plant that has shed heavily usually releafs within two months if conditions stop changing. |
| ZZ plant | Cold, usually a room below about 10 degrees or a draught from a winter window. Move it somewhere warmer and water less until spring. It regrows from the rhizomes when the temperature comes back up. |
Questions from the margin
- Why is my plant suddenly dropping leaves?
- Usually a change rather than a disease. A plant that has moved house, moved room, or met the first week of central heating sheds the leaves it can no longer support and then stops. Leave it where it is and keep the watering honest.
- How long will my fig drop leaves for?
- A weeping fig will drop a good part of its leaves after a move and grow them back over about two months if it is left alone in good light. Moving it again restarts the process, which is the commonest way people make it worse.
Checked against RHS, Houseplants: leaf drop; Iowa State University Extension, Why houseplants drop leaves.