The shift from summer to winter drastically alters the indoor environment, creating stressors like central heating, cold drafts, and drier air that challenge the survival of common houseplants. Most indoor greenery, often originating from tropical climates, struggles to adapt to these rapid environmental changes. Successfully keeping plants warm and healthy through the colder months involves adjusting placement, ambient conditions, and care routines. This guide provides practical steps to mitigate winter stress and ensure your indoor garden thrives until spring.
Managing Indoor Climate and Location
Maintaining a consistent temperature is paramount for tropical houseplants, which prefer a daytime range of 65°F to 75°F. Nighttime temperatures should drop by about 5°F to 10°F, allowing plants to metabolize sugars efficiently and conserve energy. Sudden temperature fluctuations, especially dips below 50°F, cause stress and lead to leaf damage or dropped foliage.
Drafts are a major source of cold stress, often coming from poorly sealed windows, exterior doors, and air vents. Readers should physically check for air movement near their plants, as a draft unnoticeable to a person can severely harm a plant’s tissues. Plants must be moved away from direct contact with cold glass, even if double-paned, because the glass acts as a heat sink, creating a localized cold zone overnight.
Relocation involves placing sensitive plants a few inches away from cold windows and exterior walls, which lose heat quickly. For plants that must remain near a window for light, an insulating barrier, such as a thick curtain or a piece of foam, placed between the plant and the glass after sunset can stabilize the temperature. Keep plants away from heat sources like radiators or hot air vents, as the intense, dry heat can cause leaves to scorch rapidly.
Maintaining Adequate Humidity Levels
Central heating significantly lowers indoor relative humidity, often dropping it below 20%, which is below the 40% to 60% range favored by most tropical plants. This dry air accelerates evapotranspiration, causing plant tissues to lose moisture quickly, often manifesting as brown, crispy leaf tips or edges. Addressing this atmospheric dryness is necessary for winter plant care.
The most reliable method for increasing localized moisture is using an electric humidifier. A humidifier provides consistent moisture, which is more effective than intermittent misting. Placing the humidifier near the plants creates a stable, humid microclimate that counteracts the drying effects of forced air.
A simple, non-electric solution is using a pebble tray. Place the plant pot on a shallow tray filled with water and small stones, ensuring the pot does not sit directly in the water. As the water evaporates, it raises the humidity immediately surrounding the foliage. Grouping plants together also helps, as their natural transpiration collectively increases the ambient moisture levels.
Adapting Winter Watering and Feeding Schedules
Reduced daylight in winter signals a period of slowed growth, or quiescence, for most houseplants, requiring a change in care routine. Lower light levels decrease photosynthesis, slowing metabolic processes and reducing the plant’s water needs. Overwatering is the most common cause of houseplant failure, as persistently wet soil in cooler temperatures starves the roots of oxygen and promotes root rot.
Watering frequency is determined by the plant’s current needs, not a fixed calendar schedule. The top one or two inches of soil should dry out completely before water is applied. Use room-temperature water rather than cold tap water, which can shock the plant’s root system. Thoroughly soaking the soil until water drains from the bottom ensures all roots receive moisture, but the excess water must be removed from the saucer.
Fertilization should be suspended entirely during late fall and winter for most houseplants not actively producing new growth. Since the plant is not growing, it cannot efficiently utilize nutrients, leading to a buildup of excess salts in the soil. This accumulation can chemically burn the roots, inhibiting healthy growth. Feeding should only resume when active new leaves or shoots indicate the plant has begun its spring growth cycle.