Hibernating citrus plants: this is how it works

Lemons, mandarins and their warmth-loving relatives are not made for the frosty winters in Central Europe. But if a few points about the choice of location and care are observed, it is also possible to successfully overwinter citrus plants in more northern climes.

When temperatures approach zero degrees, citrus plants should move to their winter quarters. Here we reveal what you should pay attention to when choosing a location and whether wintering outdoors is also an option. So that your citrus tree gets through the winter safely, we also explain all the important care measures that ensure a healthy plant in spring.

Which citrus plants are hardy?

Almost all citrus plants like lemon (

Citrus x lemon), Orange (Citrus sinensis) and tangerine (Citrus reticulata) can only survive temperatures down to approx. - 5 ° C.

However, this is how hardy are some hard-boiled citrus plants:

• The three-leaved orange (Poncirus trifoliata) can withstand up to - 25 ° C
• The Ichang Lemon (Citrus ichangensis) is frost tolerant up to - 15 ° C
• The kumquat (Citrus japonica) can handle temperatures as low as - 12 ° C

These and other representatives of the partially hardy citrus plants are often crossed with less tolerant species in order to obtain frost-tolerant varieties. When buying a citrus plant, you should therefore seek competent advice on how hard it is to frost. If you are not sure which cross is in your citrus tree, you should play it safe and overwinter in a frost-free location.

Important: The winter hardiness of citrus plants also depends on how they are cared for. If fertilization is carried out too late, too heavily or with the wrong nutrient, winter hardiness can suffer. Overwatering and cutting the citrus plants too late also makes them susceptible to frost. Older plants are generally harder to frost than young ones. In addition, due to regional and local temperature differences, citrus trees can safely grow in one home garden overwinter, in a less sheltered garden nearby but freeze over because of wind and humidity to add. It is therefore important to always play it safe when wintering the Mediterranean plants.

If your citrus plant is an orange or lemon tree, we also recommend our special articles on the subject Hibernate orange tree and Hibernate lemon tree.

Hibernate citrus plants

Citrus plants overwinter optimally in cool temperatures in a bright place. Even those who do not have such a space to overwinter their citrus tree can bring their plant through the cold season in a healthy way. The most important rule of thumb when choosing a location is: the cooler the place, the darker it can be and the lighter the place, the warmer it can be.

The following also applies to all citrus plants: as long as temperatures allow, they should remain outdoors. There they get as much light as possible and pests cannot spread as quickly. A sheltered place on a sunny house wall is generally ideal for citrus fruits and especially for the transitional period. The wall warms up during the day and releases the stored heat again at night - these are the conditions that Mediterranean plants love.

Citrus plants usually tolerate light and short-term frosts down to -5 ° C and can even prevent pest infestation during hibernation. So it is important to keep an eye on the weather. The citrus plants should move to their winter quarters at the latest when temperatures continue to drop or periods of permafrost announce themselves. Depending on the region, this is the case between the end of September and the end of November. It should be noted here that the temperatures locally, i.e. in your own garden or on the balcony, often differ greatly from the forecast. It is therefore better to rely on your own experience and the thermometer instead of the weather report.

Important: Citrus plants are sensitive to changes in location. Repeated repositioning or turning means great stress for the plant and should be avoided, otherwise leaves can fall.

Tip: The greatest enemy of the Mediterranean citrus plants is an autumn that is too wet, because a damp root ball reduces the frost resistance. It is therefore important to choose a permeable substrate that does not wet - conventional peat substrates are unsuitable here. Ours is better suited Plantura organic potting soilwhich is particularly permeable due to its expanded clay content and can thus promote the winter hardiness of citrus plants. In the bucket, the organic soil can also be mixed with more expanded clay or other coarser stone material so that it remains structurally stable and well permeable for a long time.

Hibernate citrus plants outside

Wintering outdoors can only be considered for citrus species with a particularly pronounced frost tolerance.

Greenhouses, sheds or garages with a source of daylight are suitable for wintering outside the house. An orangery - there are also mobile versions - offers citrus fruits an ideal wintering place. However, this purchase is associated with corresponding costs. In order to rule out temperatures that are too cold, a frost monitor or the use of frost protection candles is also worth considering. Jute or raffia mats are suitable for additional protection of the root ball. You can use a roasting thermometer to check the temperature in the tub. If the ground in the wintering location is particularly cold, you can warm the feet of the citrus plant with an insulating styrofoam sheet or an electric blanket. Check out our special article for more tips on how to Protect plants from frost.

Tip: Some service providers also offer winter storage under optimal conditions in orangeries - collection, plant protection on site and transport back to you are often included in the service.

Important: Protect citrus plants from frost
When it gets really icy outside, the temperatures can fall below freezing point, depending on the insulation, even in winter quarters. Use an electric frost monitor that heats when the temperature falls below a critical level to prevent damage to the plants. An alternative are frost protection candles, which can raise the temperature in the winter quarters by a maximum of 2 - 3 ° C when there is strong frost. With this method, however, it is important to keep a close eye on the weather report.

Wintering indoors

At the coolest possible temperatures between 1 ° C and 12 ° C in a bright place, the citrus trees can optimally overwinter. The metabolism is shut down into a cold-related sleep mode. Such cool conditions can be provided by unheated rooms, garages with daylight and winter gardens. Staircases can also be suitable, provided the plant is not exposed to any draft there.

If such a place is not available for wintering, a warmer, very light interior can also be chosen. Here the citrus tree does not go into a resting phase, but continues to grow slowly. If the plant is overwintered at room temperature, there is not enough light in houses to enable a sufficient amount of photosynthesis. Thanks to double glass and solar control glazing, the plant often receives too little usable light, even in relatively bright rooms. During a warm winter, the entire crown should be illuminated by one or more plant lamps with around 100 watts. Metal halide lamps or fluorescent tubes are suitable because they emit photosynthetically usable wavelengths.

Tip: When do citrus plants shed leaves?

• With frequent changes of location and turning of the plant.
• If the wintering location is warm but too dark: There is not enough light to generate energy in photosynthesis. Due to the warm and often dry air, however, the plant has to do a lot of energy-intensive cellular respiration. As a result of this undersupply, the citrus tree then sheds leaves in order to save energy.
• If the wintering location is cold but very bright: The brightness allows the plant to carry out a lot of photosynthesis. The cold, however, makes processes for the absorption and transport of water and nutrients in the plant very slow. As a result of this undersupply, the leaves are shed in order to slow down the photosynthesis rate.

Proper care in winter quarters

The overwintering phase is just as dangerous for citrus plants as general anesthesia is for us humans - you should therefore keep a close eye on the trees.

Check for pests

During hibernation, many pests find optimal conditions to spread and also to attack neighboring plants. To avoid damage, it is important to check for typical pests before and during winter storage. Tips to combat Scale insects, Spider mites and Mealybugs can be found in our special articles.

Fertilize properly

If the winter is cool, the last application of fertilizer of the year is recommended in October. Citrus plants should not be fertilized between November and March in order not to disturb the resting phase. In light and warm winter with lighting, it makes sense to fertilize once a month, otherwise a nutrient deficiency is inevitable. It is best to use a primarily organic liquid fertilizer with trace elements, such as ours Plantura organic citrus & mediteranean fertilizer. This is tailored precisely to the needs of citrus plants and contains all the important nutrients.

Water in the winter quarters

The plant should be watered as required, i.e. when the substrate is dry, with room-warm water that is as low in lime as possible. Plants that have been overwintered during the warm winter use and of course need water much more often. Spraying the leaves with boiled water every two to three days can counteract excessive leaf shedding. Regular ventilation, but without strong drafts, is also important.

Winterize citrus plants

When wintering, the following applies: As soon as the temperatures allow it, a citrus plant wants to be outdoors again. It could be that far from April, but the weather report should be carefully observed until the ice saints in mid-May and winter protection material should be kept ready. With the start of the new growth period in March or April, fertilizers should be regularly applied again in order to optimally supply the plant and stimulate the formation of new shoots. A primarily organic liquid fertilizer with a nutrient ratio specially tailored to citrus plants is ideal for this. Our Plantura organic citrus & mediteranean fertilizer For example, your citrus plant is optimally supplied with nutrients and, with additional iron, it prevents chlorosis - the yellowing of leaves. The organic fertilizer is safe for pets and garden animals and is simply administered via the irrigation water.

After hibernation is the best time to repot citrus plants. What To Look For When You Get One Repot the lemon tree, read in our special article.