The Secret to Growing Big Ferns
- Water your fern plant regularly as soon as the surface of its soil starts to dry out, aiming to thoroughly soak the soil. Never allow it to dry out completely as this will damage the foliage and stunt growth. Water more often if it develops yellow leaf tips. Use rainwater or low-mineral bottled water for irrigation and avoid salty or hard water. Mist your plant every day with bottled water that is low in minerals. Keep your fern on a dish of wet gravel to maintain humidity levels.
- Fertilize your fern plant with liquid houseplant fertilizer diluted by 50 percent. Apply it once a month during the warmer months of the year or while it is producing new growth and every other month during the winter. Fertilize your fern more often if its leaves turn pale or yellowish. Flush out the soil with abundant room temperature water every month to prevent root burn by excess fertilizer salts.
- Place your fern close to a west or east facing window that receives bright but indirect sunshine. Rotate the plant every week to ensure even growth. Move your fern outdoors to a shaded location during the warmer months of the year. Most fern species grow well at between 70 and 80 degrees Fahrenheit and are damaged by frost. Cold window glass can damage fern leaves during the winter. Keep them out of cold drafts and away from heaters.
- Repot your fern as soon as its roots start to grow through the hole in the base of its container. This allows the plant to continue to grow unrestricted. Use a potting compost based on peat and mix in 25 percent sharp sand to aid drainage.
- Australian tree ferns (Sphaeropteris cooperi) can grow up to 30 feet tall with a spread of 15 feet. They are suitable for tropical gardens and patios. The U.S. native Boston fern (Nephrolepis exaltata) thrives as a houseplant and produces fronds up to 4 feet long. Grow it as a potted plant or in a hanging basket.