Boston ferns (Nephrolepis exaltata) are native to tropical and subtropical regions, thriving in warm, humid environments with dappled sunlight. In their natural habitat, they grow under forest canopies, where temperatures are moderated by shade and moisture. This makes them sensitive to extreme summer heat, especially in dry or exposed outdoor conditions.
While Boston ferns can tolerate warmth, prolonged exposure to temperatures above 90°F (32°C) can stress the plant. Key challenges include:
To help Boston ferns thrive outdoors in summer, follow these guidelines:
Position the fern in a spot with bright, indirect light—such as under a tree, pergola, or north-facing porch. Avoid midday sun exposure. If grown in hanging baskets, ensure they’re sheltered from harsh afternoon rays.
Increase watering frequency to keep the soil consistently moist (but not waterlogged). Water deeply in the early morning or late evening to minimize evaporation. Mulching with organic matter (e.g., peat moss) helps retain soil moisture.
Mist the fronds daily with lukewarm water or place a tray of water and pebbles beneath the pot to boost humidity. Grouping ferns with other plants can also create a microclimate of higher moisture.
Use well-draining, peat-based soil to prevent root rot. Apply a diluted, balanced liquid fertilizer every 4–6 weeks during summer, but avoid over-fertilizing, which can stress the plant in heat.
Heat-stressed ferns are more susceptible to spider mites and mealybugs. Inspect fronds regularly and treat infestations promptly with insecticidal soap or neem oil. Ensure good air circulation to prevent fungal issues.
Watch for:
In arid or extremely hot climates (e.g., USDA zones 10+), consider growing Boston ferns in containers that can be moved to shaded or indoor areas during heatwaves. In milder coastal regions, they may fare better with minimal intervention.
