Can I Leave My Lemon Tree Outside In Winter?

By Paul Smart •  Updated: 06/13/21 •  8 min read

Can I Leave My Lemon Tree Outside In Winter? If you have bought a lemon tree for home and placed it in a pot in Spring or Summer you may be wondering if it is ok to leave the lemon tree outside as winter approaches.

Whether you can leave your Lemon trees outside is dependant upon the climate in your region, however, as a general rule if the temperature remains above the freezing point at all times in your location the tree can be left outside. However, at temperatures below 40°F (4°C), the tree can benefit from having protection applied as blossoms and young fruit are destroyed at 29°F (-2°C).

At these temperatures you will not get any fruit from the trees the following spring, but the tree will survive. At 24°F (-4°C) any mature fruit on the tree will die and the tree will lose its leaves. At this point you are really pushing your luck in terms of the trees’ survival.

Generally, this means that lemon trees should only be planted outside in zones 9 to 11 in most cases. If you are in a location where the minimum temperatures are making you a little nervous you can also apply some protection which could be an old blanket or sheet or alternative you can purchase a frost blanket. To learn more about the expected output of lemon trees click here.

The advantage of a frost blanket is that it allows light through to the plant. This enables the frost blanket to be left on for successive days. To see the latest price on Amazon click here.

When Should A Lemon Trees Be Brought Inside?

Lemon trees are happiest when the temperature is between 50°F and 80°F (10°C to 27°C) so to avoid stressing the tree it is best to bring the trees inside when the temperature starts to regularly fall below the 50°F (10°C).

When moving the trees it is important to ensure that they get adequate sunlight as they need to continue, photosynthesize. As such it is important to ensure that they are placed in a bright location and that does not fall below the freezing point.

Ideally, the temperature should remain above 40°F (4°C) or higher. This can sometimes be problematic if the tree is transferred to a greenhouse or conservatory where it can get too cold. In these situations, it will necessary to heat the area.

Due to the moist conditions, it is better to use a purpose-built greenhouse heater rather than a domestic heater largely because greenhouse heaters are made of rust-resistant components which are suited for humid environments. The unit we recommend for this purpose is the Bio Green PAL 2.0/USDT Palma Greenhouse Heater which includes the heater and a thermostat for accurate control of temperature and minimize cost.

How To Look After A Lemon Tree Indoors

For many people that grow lemon trees indoors for part of the year there are a few important tricks that you need to employ to ensure that the tree does not suffer too much during this period. This is a problem because a decline in the health of the tree over the winter period will reduce the capacity of the tree to produce fruit in the growing season when it can be outside.

There are a few little tricks that can really help the tree do better.

Increase The Humidity.

In Interior spaces, particularly in winter, where heater is running constantly, the humidity level in a room can fall dramatically. It is common to see 10 percent humidity in these environments compared to closer to 50% or higher in many outdoor locations.

This reduction in humidity results in the tree losing moisture more rapidly to its surroundings which can stress the tree. To reduce this effect you can place trays of water around the room that will slowly evaporate to increase the humidity. These trays will need to be refilled periodically.

Increase Air Movement

The second trick to improve the health of your lemon trees indoors is to increase the air movement the will improve the trees’ access to nutrients in the air. The best way to do is using a fan heater which will both increase air movement, heat and also can be used to improve humidity.

When positioning the fan heater in a space it should not be pointed directly at the tree as it will dry it out rapidly, instead, it should be positioned in such a way to ensure that the gently moves around the room without blasting a particular plant.

To increase the humidity the trays of the water should be positioned so that the airflow pass over them to increase the evaporation rate. The position of the trays can be used to control rate of evaporation and also therefore the humidity.

Plenty of Water

The next tip, which is kind of obvious, is to make sure that the soil of the lemon tree is always moist but not sodden. Lemon trees are susceptible to root rot if they remain waterlogged. This means water regularly but allowing the surface to dry out slightly between watering which usually means that the soil around the rootball will remain moist.

If the leaves on the Lemon tree begin to curl that is a sure sign that the tree is too dry. The curling of the leaves is an attempt by the plant to reduce moisture loss which indicates that the plant is becoming stressed. The other option to improve moisture retention is to add hydrogels (sometimes referred to water crystals) to the pot.

Water crystals have been shown to retain moisture for longer reducing the chance of the soil drying out. To read an article on the extent of the improvement in moisture retention click here.

Replace Soil Nutrients

For a tree in a pot to remain healthy in the long term whether it is being stored inside or outside the tree needs to be continually provided with nutrients otherwise the soil will become tired. The symptoms that you are likely to see from a Lemon tree are the appearance of yellow spots on the leaves or the general yellowing of the leaves. Yellowing is usually an indication that the rate of chlorophyll production has fallen in most cases due to a lack of nutrients.

To ensure that the tree has adequate nutrients it is advisable to use a slow-release fertilizer that if specifically formulated for citrus trees. Each application should supply the tree with 3 months of nutrients at least. It is advisable to apply the fertilizer in the fall and the spring. There are many different fertilizers on the market that are suitable, to see the one that I use click the link here.

Adequate Sunlight

The other important ingredient is adequate sunlight. This can be a problem in those dreary winter days because the light levels are generally low. However, there a couple of things that you can do to improve the situation.

The first is to ensure that any windows that the light comes through are as clean as possible and free of debris.

The second thing that can be done is to maximize the number of reflective surfaces where the tree is being stored. Reflective sources allow an opportunity for the light to be held in the space longer. If the plants are being stored in a greenhouse you can use reflective bubble wrap on the northern side of the greenhouse (assuming you are in the northern hemisphere).

The reflective insulating material will help hold the heat and increase the level of light in the greenhouse. This material is cheap and readily available on Amazon, click here to see the latest price.

If the light is still an issue the other alternative is to use an artificial light source. However, it is important to note that you need to mimic normal daylight hours which means having the light on for 12 hours a day. To avoid the need to be constantly turning it on and off it is best to purchase a light that is designed specifically for plants and has a timer.

The one we recommend is that GHodec Sunlight light because it also 2 globes and 5 different light intensity settings allowing greater control over the degree of light exposure, to see the latest price on Amazon click here.

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Paul Smart