How To Overwinter Boston Ferns So They're As Good As New In Spring

If you thought you knew everything about Boston ferns before planting, think again. Sometimes also called sword ferns, these plants boast lush, feathery fronds, but keeping them healthy through winter can be challenging due to their sensitivity to cold weather. These tropical plants thrive in warm, humid conditions, making climate control a key factor for survival. If the temperature dips below 50 degrees Fahrenheit, Boston ferns can start to experience stress. Prolonged exposure to cold can cause yellowing leaves, stunted growth, and in some extreme cases, even the death of the plant. As the temperature continues to drop, it is very possible that your fern could completely wither. The biggest issue gardeners face is that Boston ferns, originally native to tropical and subtropical regions, require consistent warmth and humidity. This poses a problem for those of us who live in colder climates.

In terms of hardiness, Boston ferns (Nephrolepsis exaltata) thrive in USDA zones 8B to 11, where temperatures rarely drop below freezing. So, in warm, frost-free states such as Florida, Texas, Louisiana, and parts of California, you can usually leave these plants outdoors year-round without worrying about the weather. However, for those living in chillier areas like the Midwest or Northeast, the winter months pose a real threat to them. Short of keeping your Boston fern in a regulated, temperature-controlled environment, you'll need to overwinter them carefully to ensure they come back strong in the spring.

Boston ferns are no shrinking violets and flourish if exposed to a humid environment and not placed in direct sunlight. Without sufficient moisture, their fronds can dry out, and low light can also affect the color of their leaves. If you can't replicate their preferred tropical environment, your best option is to let the fern go dormant for the winter. Sword ferns are one of the popular plants that need to be overwintered before temperatures start dropping by placing it in a cool, sheltered space (like your shed or garage) until warmer weather returns.

Before moving your fern, start by pruning back overgrown or damaged leaves to help it conserve energy and prevent excess moisture loss during its dormant period. Once pruned, water it once a month, giving it enough moisture to keep the soil from drying out completely. Do not overwater it at this stage, as sword ferns are prone to root rot in cooler conditions. Also, avoid fertilizing the soil during this time as it won't need extra nutrients.

Once the weather warms, you can gradually water it more frequently, adding a diluted fertilizer to promote new growth if needed. Slowly reintroduce the fern back to your garden by placing it outside during the day and bringing it in at night until it has fully adapted to the warmer temperatures. If you're unsure if it's doing well, look out for new leaves indicating that it has fully acclimated to the new season.

Boston ferns aren't the only plants that benefit from overwintering. Many tropical and subtropical plants, such as hibiscus, mandevilla, and geraniums, require protection from cold weather if you want them to survive winter. These plants follow a similar overwintering process — pruning, reduced watering, and keeping them in a frost-free environment until spring. It's crucial to regularly monitor overwintering plants for signs of mold or pests, as these issues can develop in a dormant environment.

To help your sword fern thrive, consider placing a humidifier nearby if you're growing it indoors. You could even create a trendy humidity tray for your prized plants by setting the bloom on a shallow dish filled with water and pebbles. This helps maintain the moisture levels the fern needs to stay healthy. Additionally, during the warmer months, ensure your fern is in a shaded outdoor area, as direct sunlight can scorch the fronds. Boston ferns love consistent watering, sufficient humidity, and gradual transitions between indoor and outdoor environments. Taking these steps will ensure that they remain healthy during the warmer months.