How Do I Overwinter a Citrus Tree in a Cold Climate?

In temperate climates where temperatures regularly fall below freezing, citrus trees in containers must be moved to a frost-free position for winter. Getting the overwintering conditions right — particularly temperature, light, and watering — determines whether the tree emerges in spring in good health or having lost most of its leaves and vitality. The good news is that citrus are not difficult to overwinter if the fundamental requirements are met.

When to bring citrus indoors

Move container citrus indoors before the first autumn frost — typically October in most of northern Europe. Do not wait for the frost to arrive; even temperatures just above freezing overnight can stress citrus. On the other hand, moving indoors too early in late summer means the tree misses valuable late-season warmth and light outdoors. Watch the forecast from late September and bring the tree in when overnight temperatures are consistently dropping below about 7°C.

Best overwinter location

An unheated but frost-free greenhouse is the ideal overwinter location — it provides good light, adequate coolness, and protection from frost. A cool conservatory or well-lit porch is the next best option. A centrally heated living room is the most common choice but the least ideal — the combination of warmth (above 18°C) and low winter light causes the tree to try to grow actively but without sufficient light to do so well, resulting in weak, pale, pest-prone growth and heavy leaf drop. If a living room is the only option, place the tree in the very brightest possible position and away from direct radiator heat.

Watering in winter

Reduce watering significantly in winter. A tree in a cool environment with low light uses water very slowly. Overwatering in winter — often caused by sticking to a summer watering schedule — is one of the most common ways citrus are killed. Check the compost carefully before each watering and water only when it is dry several centimetres below the surface. Once every two to three weeks may be sufficient in cool conditions.

What to expect in spring

As days lengthen and temperatures rise in March, begin moving the tree to a warmer, brighter position and gradually resume a normal feeding schedule. Harden the tree off before moving it back outdoors in late May — do not move from a warm room directly into outdoor conditions without a week or two of intermediate exposure. A sunny, sheltered spot against a south-facing wall is ideal for the first weeks outdoors.