University of Vermont Extension Department of Plant and Soil ScienceFall ArticleGROWING FERNS SUCCESSFULLY INDOORSBy Dr. Leonard Perry. Extension ProfessorLooking for a houseplant that requires little care, thrives in low-lightconditions, and adds visual interest to a room? The answer is thefern, which has foliage ranging in appearance from delicate to dramatic,depending on plant family.Ferns do best with indirect lighting. A north-facing window isideal although during the winter months, when the sun is low on the horizon,an east window is fine for these plants. Avoid south and west-facingwindows, as the intense sunlight may scald the leaves or fronds of theferns, depending on the intensity of the light. Or they may dry outfaster or scald the leaves if there is low moisture in the soil or air.Most ferns like an average room temperature of 65 to 75 degrees F duringthe day, up to 10 degrees cooler at night. If temperatures exceed75 degrees F, you may need to water more frequently. Below 60 degrees,add water only when the soil is dry to the touch. Some of the moretropical ferns may grow poorly, preferring the higher temperatures.Consistent watering, keeping the soil evenly moist, not wet, is alsokey to the health and well being of the plants. Overwatering causesthe fronds to yellow and wilt and may eventually lead to root rot and fungaldiseases, especially if the pot is allowed to sit in water. Too littlewater also causes wilt. A few varieties, such as Rabbit's Foot Fern,Brake ferns, and Holly Fern are an exception to the consistent wateringrule. For these, you may allow the soil to dry out slightly betweenwaterings.Ferns, many of which are native to the tropics, like high humidity,which is why they do well in bathrooms. But you also can increasehumidity around the ferns by placing the pots on a pebble-lined tray. Add water to the pebbles, making sure the bottoms of the pots do not touchthe water in the tray. The evaporation will add extra humidity aroundthe plants. The best solution is to have a room humidifier adjacentto the plants. This also benefits people indoors in dry homes aswell. Homes often have five to 10 percent relative humidity. Humidifiers might raise that to 30 to 50 percent, which is really minimumfor ferns to do best (although they may tolerate slightly lower humidity),and in native climates often have 70 percent or higher relative humidity.Or double pot your ferns to provide more moisture. Place the maincontainer into a second, larger container that you have lined with moistsphagnum moss. Keep the moss moist or even wet. Use plasticpots, which don't dry out as quickly as clay pots. The latter arenot recommended for many ferns indoors, unless you use the pot in pot methodas described above. A clay pot surrounded by moss then the ceramicor plastic pot on the outside is probably ideal.In addition, misting the foliage, especially in winter, will increasethe humidity. Just be careful not to mist the furniture and outerwalls. Use room temperature water as cold water may spot the leaves.You'll know when the humidity is too low as the tips of the fronds willbrown or die back. Maidenhair, Staghorn, and Boston Fern are especiallysusceptible to lack of adequate humidity.Ferns require only light feedings of fertilizer once a month from Aprilthrough September unless actively growing in winter months. Applyliquid houseplant fertilizer at about one-half the recommended rate. Too much fertilizer will scorch the foliage. Newly potted plantsshould not be fertilized for four to six months, again unless there areindications of active growth.Plant diseases are rare in ferns grown indoors although your plantsmay suffer from infestations of scale insects, mealybugs, and mites. Handpicking or spraying with water are the best options for control aspesticide sprays may injure ferns. If you must use, choose the leasttoxic product for the pest and read the label carefully before applying. Check at least weekly to catch pests early. If ferns are infestedwith scales, the easiest way to control is to cut off affected fronds. If infestation of out of control, you may need to discard the plant beforethe rest of your houseplants are affected.Ferns will require repotting every few years. Repot in the spring,using a purchased soil-less mix that is 50 percent peat moss. Divideovercrowded plants by removing from the pot and cutting carefully betweenrhizomes (fleshy roots). Keep as many leaves as possible per division.It is also possible to propagate new plants by spores. In thesummer plants will produce spores (brown dots) on the undersides of theleaves. When these spores darken, remove the leaf and place in apaper bag. As the leaf dries out, the spores will fall off. Plant in a peat-based seed starting mix. Water well, and place ina plastic bag. Temperatures of 65 to 70 degrees will encourage sprouting.When fronds are one-inch high, remove the plastic bag and transplantin groups in small pots. At two to three inches, transplant to individualpots. This can be tricky as it often takes quite a while for frondsto reach transplant height, and moss and algae or other growth may appearfirst and kill off young plants, so be forewarned if you decide to propagateyour own ferns.The following ferns can be grown as houseplants. Or ask your localgarden center for recommendations.--Birdsnest Fern (Asplenium)--one of the easiest ferns to grow;may reach 18 to 24 inches tall although in humid room like greenhousemight get to be six feet high and across; has broad, light green, leathery,undivided fronds that grow upwards, giving the plant the look of a bird'snest.--Boston Fern (Nephrolepis)--also known as the ladder or swordfern; has long, delicate fronds and light green foliage; grows from 10inches to three feet, depending on cultivar; ideal for hanging baskets;fern may drop leaflets, especially if too dry, making this a "messy" plantto grow; some newer dwarf compact cultivars are an excellent choice fora houseplant. These were especially popular in Victorian times.--Brake Ferns (Pteris)--several varieties are available, includingsome with variegated foliage; may be grown as a table fern or in a hangingbasket; prefers diffused light and nighttime temperatures of 50 to 55 degreesF, 68 to 72 degrees F during the day.--Button Fern (Pellaea)--good plant for small spaces as it onlygrows 12 to 18 inches tall; it is often dark green and has round, slightlyleathery "button-like" leaves attached to slender stems.--Holly Fern (Cyrtomium)--also known as the fishtail fern; hasbright, glossy, leathery leaves; rather un-fernlike in appearance; preferscool to moderate temperatures and indirect sunlight; requires less humiditythan most other ferns; ideal for lower light conditions.--Maidenhair Fern (Adiantum)--fast-growing fern that needs highhumidity and consistent moisture to survive; foliage is lacy with small,fan-shaped leaves; does best in a north window. If it dries out, the foliagemay die as the plant shrivels. However, it doesn't "unwilt"when watered as many houseplants will, but new shoots should appear.--Rabbit's Foot or Ball Fern (Davallia)--excellent fern for hangingbaskets as the furry, creeping rhizomes hang over the edge of the container,resembling a rabbit's foot; needs to be planted with rhizome above soillevel instead of buried; very sensitive to salt and thus needs to be wateredwith soft water.--Staghorn Fern (Platycerium)--leaves are wide, flat, down-covered,and resemble an elk's antlers; slow-growing but can reach three to fourfeet in height; should be grown in sphagnum moss with the shield (the brownpart from which the green "antlers" emerge) wired to a piece of wood orcork bark; fern is really marginal in many interiors as it needs lots ofhumidity; water by taking entire wood slab or cork bark and moss off thewall or wherever it is hanging, then immerse with plant shield into a panor tub of water. A bath tub without soap suds works best. Watershould be lukewarm, not hot. Allow to drain before rehanging.Return toPerry's Perennial Pages, Articles
