Overwintering lemon tree outdoors: tips to protect against frost

Overwintering potted lemon tree (and other citrus trees)

If you grow your lemon tree in a pot, wintering is an essential step, especially in regions where frost is frequent. From autumn onwards, protect the lemon tree from cold and bring it indoors to a frost-free place.

Where to winter your potted lemon tree?

• Place it in a well-lit spot, in a conservatory, an unheated greenhouse or any other bright room with a winter temperature ideally between 8 and 10 °C.
• Avoid overly heated living rooms with dry air, and garages, which are often too dark.

If winter temperature in your region does not fall below −5 °C, you can leave your potted lemon tree outdoors in winter, provided you protect it:

• with a winter fleece or cover,

• also wrapping the container to limit heat loss (roots in pots are very sensitive to cold).

Remember to:

• elevate the pot slightly to avoid direct contact with frozen ground,

• occasionally air the above-ground parts by removing the winter cover to prevent emergence of diseases or parasitic organisms linked to a confined medium.

During wintering of potted lemon tree:

During dormancy, space out watering (about twice a month) and stop fertiliser applications. To reduce stress when growth resumes, re-acclimatise your lemon tree gradually as soon as fine weather returns: put it out during the day at first, bring it in at night, then reinstall it permanently outdoors.

A lemon tree wintered under cover can, however, be exposed to certain parasitic organisms such as red spider mites, scale insects or whiteflies. Regular misting of foliage helps maintain good humidity levels and prevent their development.

For winter, best to bring citrus trees in pots into a bright room, such as a conservatory or an unheated greenhouse

Overwintering lemon trees outdoors in open ground

A lemon tree grown outdoors, planted in open ground, can overwinter outside, provided climate in your region is relatively mild. Overwintering a lemon tree outdoors is considered feasible in the orange-growing zone, that is where winter temperatures do not fall below -5 °C.

To protect a lemon tree planted in open ground effectively during winter:

• Put a winter cover or protective sleeve around the branches, without smothering them.

• Mound straw or a thick mulch around the base to protect the roots from the cold.

• If possible, install windbreaks (reed screens, hedges) around the tree.

• Avoid applying fertiliser in autumn, which would encourage growth vulnerable to frost.

To monitor during winter:

• Occasionally remove the winter cover to aerate plant and prevent disease.

• Monitor weather forecasts: in case of an exceptional cold snap, add extra thermal protection (double cover, tarpaulin, bubble wrap…).

Lemon tree in winter, even in open ground, remains sensitive to prolonged cold. These simple measures help protect it.

After overwintering the lemon tree

End of overwintering for potted or in-ground lemon trees should be gradual to avoid shock, especially after several weeks spent sheltered from cold.

For lemon trees in pots:

• Wait until all risk of frost has passed, including late frosts.
• Monitor minimum temperatures: they must remain consistently above 5°C.
• Move pot outdoors during day into full sun, but sheltered from wind.
• Bring it back in at night for a few days.
• After a week or two of hardening, you can permanently re-site the lemon tree outdoors.
• Gradually resume regular watering.
• Wait until mid-April or May to resume fertiliser applications.

For in-ground lemon trees:

As soon as temperatures become milder:

• Gradually remove fleece or winter cover,
• Proceed in stages if wide temperature fluctuations persist.
• Also take advantage of end of overwintering for pruning your citrus trees, it’s the ideal time for this.
• Lightly rake surface of mulch to aerate soil.

My lemon tree has been damaged by frost... What should I do?

Finally, if your citrus has been frosted, it may still recover (especially if the frost was short-lived). Wait a while, then when temperatures become milder, prune it back severely. With any luck, if it wasn’t completely damaged by the frost, it will soon produce new shoots.