The first cold night of the year rarely announces itself. You check the forecast before bed, see a small number with a minus in front of it, and the lemon tree on the terrace stops looking like a Mediterranean flourish and starts looking like a problem. Lemons are tougher than their glossy leaves suggest, but they are not hardy, and one hard frost can strip a young tree of every leaf and set it back a whole season. The real work of overwintering happens in the two or three weeks before that night, and it is mostly a matter of small, unglamorous checks.

The Ten-Point Checklist

Work through this list in order, ideally on a dry weekend in early autumn. Each point is expanded in the sections below, so this is the version worth printing and pinning up in the shed.

1. Find your first frost date and plan to move the tree indoors a fortnight before it.
2. Inspect the whole plant — leaf undersides, stems, the rim of the pot — for scale, mealybug and mites.
3. Scrub the pot and saucer and clear fallen leaves from the surface of the compost.
4. Choose a bright, cool position before you carry anything through the house.
5. Clean the glass and wash the leaves so winter light actually reaches the tree.
6. Cut watering right back and never let the pot stand in water.
7. Lift the pot off cold floors and paving with feet or a trivet.
8. Plan a daily air exchange — an open window on a mild day, or a small fan on low.
9. Stop feeding once growth slows, unless the tree is warm and actively growing.
10. Book ten minutes a week for a proper look at leaves, soil and fruit.

Timing: Move Before the First Frost, Not After

The trigger is night temperature, not a date on the calendar. Once nights start falling to around 5°C, citrus has effectively stopped growing for the year and is ready to come in. Waiting for the first frost warning usually means moving a stressed, half-frozen tree into a dark hallway, which is the quickest route to a winter of dropping leaves.

Move gradually if you can. A week on a sheltered porch, then a week beside the back door, then inside. The tree adjusts to lower light instead of going from full October sun to a dim corner in one afternoon. Leaf drop in November is nearly always a shock reaction to light and temperature, not a disease.

Before the pot crosses the threshold, tidy up. Strip fallen leaves and weeds from the compost surface, wipe the rim and saucer, and check the drainage holes are clear. Anything you carry in — slugs, snails, vine weevil — will spend the winter comfortably indoors at your expense.

Light: Bright and Cool Beats Warm and Dim

A lemon in winter wants the brightest spot you own and the coolest one it will tolerate: an unheated conservatory, a glazed porch, a south-facing spare room that sits around 8–12°C. At those temperatures growth slows to a crawl, which is exactly what you want. Pale, leggy shoots produced in a warm, dim room rarely survive to spring.

Aim for at least six hours of direct light. Wash the inside of the window in autumn — grime and condensation cut light more than most people expect — and wipe the leaves with a damp cloth every few weeks. Dust is a light filter and a hiding place for mites.

If the only spot you have is warm

Compensate with more light. A simple LED grow light run for twelve to fourteen hours a day, positioned 20–30 cm above the canopy, makes a real difference. Turn the pot a quarter turn each week so the tree grows evenly rather than leaning permanently into the glass.

Watering: Fewer Litres, More Attention

Most winter losses are watering mistakes. Cool compost stays wet for a long time, and citrus roots sitting in cold, saturated soil rot quietly. The rule is simple: water thoroughly, then wait until the top few centimetres are dry before watering again. In a cool room that might mean every ten days to a fortnight; in a warm, bright room, more often.

Use water at room temperature, water in the morning, and always empty the saucer. Lift the pot to judge its weight — a light pot needs water, a heavy one does not.

• Yellowing lower leaves and a sour smell from the compost point to overwatering.
• Crisp, curled leaf edges and a bone-dry pot mean you have gone too far the other way.
• Sticky leaves or a black film on the floor usually mean sap-sucking pests, not water.

Humidity matters too, especially in heated rooms. Grouping plants together, a pebble tray, or a small humidifier all help. Avoid misting in a cold, still room in the evening — it invites fungal problems rather than preventing them.

Ventilation, Air Movement and Pests

Air that moves

Still, damp air is the enemy. A sealed porch with condensation running down the glass is a nursery for botrytis and sooty mould. Open a window for fifteen minutes on a mild day, moving the tree out of the direct draught, or run a small fan on its lowest setting nearby — not pointed straight at the canopy — to keep the air gently circulating.

A two-minute pest check

Turn over a handful of leaves every week. Scale looks like small brown limpets along the midrib, mealybug like white cotton in the leaf joints, and spider mites leave fine webbing with a speckled, bronzed look to the foliage. Caught early, they can be wiped off with a soapy cloth or treated with horticultural soap. Left until March, you will be dealing with a population that has had all winter to multiply.

When the Tree Stays Outside

In mild or sheltered gardens a lemon can spend winter outdoors against a south-facing wall, provided it is protected rather than simply left out. Group pots together, wrap the pot — not the trunk or foliage — in bubble wrap or hessian, and stand it on feet so it is not sitting on freezing paving. A thick mulch on top of the compost helps, as does a fleece cover thrown over the canopy on the coldest nights and removed the following morning.

Meyer lemon is the most cold-tolerant lemon most gardeners grow, and will shrug off a brief dip below freezing with protection. A true lemon will not. If your winters regularly drop below -3°C, plan on bringing it in.

Water sparingly but do not forget it entirely. A dry pot in a cold wind can be as damaging as wet feet. Check the compost every couple of weeks and water in the morning if the pot feels light.

A Weekly Habit, Not a Winter of Worry

Overwintering a lemon is not really ten jobs done once. It is a routine: ten minutes a week with a cloth, a finger pushed into the compost and a look under the leaves. Do that, and the tree reaches spring with its foliage intact and flower buds already forming.

Keep the room cool, the light bright, the water measured and the air moving. If something goes wrong — a sudden leaf drop, a sticky patch on the windowsill — deal with it that week rather than in March. Lemons forgive a great deal, but they do not forget a winter spent in the dark.

Photo: StockSnap / Pixabay