Most ferns are woodland or wetland plants that thrive in shady, moist places. When they're invited indoors, allowances must be made for their exotic needs. Central heating and air conditioning removes the humidity that ferns need in their native settings. Compensate for these disparities by assessing your fern’s needs and designing its home so that it can adapt gradually--and successfully--to indoor life indoors.
Plant or re-pot your fern in a well-drained container. Drill extra holes in a clay pot or use a moss basket to allow air to circulate freely through the roots. Fill the container with a soilless potting mixture for ferns, or make your own using equal parts of well-rotted compost, humus and peat moss; the result is as close as you’ll get to a forest floor. Staghorn ferns are the exception; they are grown in sphagnum moss on a piece of tree or cork.
Put the fern in a place where the temperature is right. Brake ferns need nighttime temperatures of 50 to 55 degrees F and daytime temperatures of 68 to 70 degrees F. Some tropicals, however, may want warmer temperatures. Consider that the temperature near a window may be too warm during summer for daytime and too cold during winter for nighttime temperatures. Set a thermometer next to the fern to check its environment before placing it permanently.
Establish and maintain a humidity regimen. Water and mist with tepid water; your soil is very porous and ferns don’t like wet feet, so resolve to water when soil begins to dry. Put the fern on a tray filled with 2 inches of pebbles and 1 1/2 inches of water to provide better humidity levels. Set sphagnum baskets and staghorn plaques in a soap-free basin of tepid water to re-hydrate both container and soil.
Feed ferns half-strength houseplant fertilizer monthly from spring to early fall. Their primary need is nitrogen to grow. They should not need fertilizer from October to March, unless they are actively growing.
Groom ferns regularly. Remove fading foliage and check for honeydew (a sign of fern scales), mealybugs or other pests. Check tops and bottoms of leaflets, and if you find pests, isolate the plant and apply an insecticide that is marked as safe or designed for ferns.
Things You Will Need
- Container with good drainage
- Potting soil
- Sharp sand, peat moss, humus or manure
- Fish emulsion or houseplant fertilizer
- 2-inch trays or saucers and pea gravel
- Start your fern with the right potting mix. Staghorns like some oak leaves and peat worked into their sphagnum moss; button ferns require extra lime and holly ferns like a shot of manure in their soil, as do most Boston fern varieties.
- Fish emulsion is a good choice for fertilizer for ferns. Make sure that you choose a brand that is "deodorized," or marked for indoor use, or you may have to drag the cat out of the fern basket.
- Ferns are accustomed to humidity near 70 percent; about the level in a bathroom with the steam shower going. A room humidifier can only achieve half of that. Maidenhair, Staghorn and Boston Fern require daily or more frequent misting to meet their moisture requirements.
- Never set ferns in direct sunlight. Put them close to--not in--north windows, behind sheer curtains near others and let them spend their outdoor summers in deep shade.
- Take care when misting ferns. Avoid using softened water; the salts will settle on leaf surfaces. Avoid wetting fine-leaved ferns like foxtail, maidenhair, lady and curly ferns.
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