With its delicate, silvery green leaves and compact growth habit, silver lace fern (Pteris ensiformis "Evergemiensis") is an attractive ornamental perennial that can brighten up an indoor window ledge or an outdoor border in the tropics. Also known as sword brake fern, silver lace fern is fairly easy to maintain and care for once you provide the plant with the proper cultural conditions.
Choose a location for the silver lace fern with partial sunlight or partial shade, such as a north-facing windowsill. Avoid direct, blazing sunlight, which will quickly dry out the fern. Ideal indoor temperatures should be between 50 to 55 degrees Fahrenheit during the night and 68 to 72 degrees Fahrenheit during the day. Outdoors, silver lace fern is only hardy in U.S. Department of Agriculture plant hardiness zones 10A to 11. When grown outdoors either inside containers or planted in the ground, select a location with dappled sun to partial shade. Bring outdoor containers inside to a protected location in the event of a sudden frost or freeze.
Plant the fern in a porous, well-draining potting soil, such as a peat moss-based house plant soil. For ferns in containers, choose a pot with a hole in the bottom for drainage. From April to September, fertilize monthly with a balanced, liquid houseplant fertilizer, mixing seven drops of fertilizer per quart of water. Clemson Cooperative Extension recommends not fertilizing newly purchased ferns or transplanted ferns for the first six months. Excessive fertilization can lead to brown, wilted fronds. Do not fertilize from October to March. Grow outdoor ferns in loamy soils that are moist but drain well and range from neutral to acidic.
Water the silver lace fern whenever the soil surface starts to feel dry. Water deeply, until water drips through the bottom of the container, and empty the excess from the tray after a couple of minutes. Although the soil should never become bone dry, consistently wet or water logged soil may lead to root rot and other diseases. Opt for lukewarm or room-temperature water, as cold water can injure the tropical plant's roots. Keep the soil for outdoor ferns moist but not sopping wet.
Check the silver lace fern's fronds occasionally for dust, which can contain mites and insects and make it difficult for the plant to absorb sunlight. If fronds are dusty spray the fern with lukewarm water or carefully dip it upside down in a sink or tub. If you find insects on the plant, pick them off by hand or spray them off with lukewarm water. Possible insects may include mealy bugs, spider mites, which appear as tiny, reddish dots and scale insects. If possible, increase humidity with a room humidifier and keep the plant properly watered.