Meyer lemon trees, a hybrid between a lemon and a mandarin orange, are popular for container gardening due to their sweet fruit and compact size. While they flourish outdoors during warm months, these subtropical evergreens lack the cold tolerance to survive freezing temperatures. Bringing the plant indoors for winter is necessary in most climates to protect the tree from stress and permanent damage. A successful transition requires attention to specific temperature cues and thorough preparation.
Identifying the Critical Temperature Thresholds
Moving a Meyer lemon tree indoors is based on monitoring nighttime temperatures, since the potted root system is vulnerable to cold. The first signal, the caution zone, is when nighttime temperatures consistently drop below 50°F (10°C). Although the tree can tolerate this range, prolonged exposure slows its metabolic processes, signaling cold stress and often causing leaf drop.
The tree must be moved inside well before the danger zone is reached, which occurs when temperatures approach 32°F (0°C). Meyer lemon trees are damaged or killed when temperatures drop below 30°F. To prevent irreparable damage, the safest course of action is to complete the move when nighttime lows are forecast to drop below 40°F (4.4°C).
A gradual transition period mitigates the shock of moving from bright outdoor sun to the dimmer indoor environment. About two weeks before the final move, place the tree in a sheltered, partially shaded outdoor location, such as a covered porch. This helps the leaves acclimate to reduced light intensity, lessening the risk of significant leaf loss indoors.
Essential Pre-Move Preparation
Before bringing the tree inside, a detailed inspection and treatment for common garden pests is essential. Citrus trees are highly susceptible to pests like spider mites, scale insects, and mealybugs, which rapidly multiply in warm, dry indoor air. Check every part of the plant, including the top and underside of all leaves, along the stems, and in branch crevices.
A strong blast of water from a hose is an effective initial treatment, physically dislodging adult pests and washing away egg masses. After the water treatment, apply a horticultural oil, such as neem oil, or an insecticidal soap solution to the entire plant, ensuring thorough coverage. Apply these non-toxic treatments a few days before the final move to maximize their effect.
The soil surface and the exterior of the pot must also be addressed to prevent introducing unwanted organisms. Gently scrape away the top inch of soil and replace it with fresh potting mix to eliminate potential fungus gnat larvae or insect eggs. Additionally, wipe down the outside of the container with a mild soap solution to remove debris and hitchhiking insects.
This period is also a practical time for light pruning to manage the tree’s size and shape for its indoor location. Remove dead, damaged, or crossing branches to improve air circulation and reduce the plant’s footprint. Finally, slightly reduce watering in the days leading up to the move; allowing the soil to dry minimizes the potted tree’s weight and discourages fungus gnats indoors.
Optimizing the Indoor Environment (Winter Care)
Once inside, the Meyer lemon tree requires specific conditions to sustain health until spring. Light is the most limiting factor for indoor citrus, as the tree needs high intensity light for growth and fruit production. The ideal indoor placement is directly in front of an unobstructed south-facing window, offering maximum duration and intensity of natural sunlight.
Since winter daylight hours are shorter and indoor light is less powerful than sunlight, supplemental lighting is often necessary. Position a dedicated grow light close to the foliage and keep it on for 10 to 12 hours daily to compensate for reduced natural light. This helps prevent the leaf drop that commonly occurs when citrus transitions indoors.
The ideal ambient temperature range for an overwintering Meyer lemon is between 55°F and 65°F (13°C to 18°C). Place the tree in a cooler room, away from heat vents or drafts, which cause rapid fluctuations in temperature and humidity. Indoor heating systems drastically reduce humidity, a major stressor for subtropical plants.
To counteract dry air, increase local humidity by placing the potted tree on a tray filled with pebbles and water, ensuring the pot is not sitting directly in the water. Alternatively, a small room humidifier placed nearby can maintain humidity. During winter, the tree’s water and nutrient needs decrease substantially. Reduce watering frequency, allowing the top inch of soil to dry completely before rewatering. Stop fertilization entirely unless the tree is actively flowering or holding fruit under supplemental grow lights, requiring minimal feeding once a month.