Background:

Ferns are excellent plants for low light conditions. The foliage can range in appearance from delicate and airy to dense and dramatic. There are ferns with furry rhizomes that reach out of the pot like little feet, appropriately named squirrel foot and rabbit's foot ferns. Staghorn and Bird's Nest ferns also make a strong visual impact on a room. While green may be the only color choice, the texture and variation of leaf shape make ferns an elegant addition to rooms with little light. Ferns can be hardy and low-maintenance indoor plants.

Culture:

Most ferns require similar care--low light, high humidity, and a light feeding of a balanced fertilizer. Variations occur in the amount of water a particular fern requires and the temperatures it can tolerate. A soil-less potting mix containing peat moss is an excellent choice for potting ferns, as they prefer potting soil with good drainage and high organic content.

Indirect light is a necessity. Ferns need a north-facing window. South or west-facing windows are to be avoided, unless they are curtained. The foliage will burn if put into direct sunlight. Ferns will not survive a total lack of light. Like all green plants ferns need sunlight to photosynthesize nutrients.

High humidity is a requirement for all types of ferns, but it is especially important for Maidenhair, Staghorn, and Boston Fern. In order to raise the humidity around the fern, place their pots on a tray containing pebbles and a small amount of water. Never let the bottom of the pot touch the water in the tray. A pot that constantly sits in water will encourage fungus diseases and root rot. Misting on a regular basis will help increase humidity. Ferns that need especially high humidity can be grown in bathrooms and terrariums. Browning or die back on the tips of the fronds is evidence of low humidity. While most ferns enjoy a moist atmosphere some varieties like to dry out slightly between watering. Rabbit's Foot Fern, Brake Ferns and Holly fern should not be watered until the surface of the soil is dry.

Most ferns do well in average room temperature--68 to 72 degrees F during the day and 62 to 65 degrees F at night. Some varieites, such as Brake Ferns and Staghorns, need cooler night temperatures.

Ferns are not heavy feeders. They only need to be fertilized once a month with a liquid fertilizer at one-half strength.

Propagation:

Ferns can be propagated by division. Early spring is the best time to repot or divide a plant. Remove the plant from the pot and carefully cut between the rhizomes. You want to keep as many leaves as possible on each division. Repot in a good sterile potting soil. Do not feed a newly repotted plant for at least 4-6 months.

Ferns may also be propagated by spores. During the warm months of summer, ferns produce dot-like structures called spores on the underside of the leaves. When the spores ripen and turn dark remove the leaf and place in a dark container like a paper bag. Let the plant dry out. Once dry you can shake the leaf and thousands of spores will fall free. Place the spores in pot containing a peat based seed-starting mix. Work carefully as the spores can blow away with the slightest breeze. Water the container from the bottom up. When the soil surface is damp, place the pot in a plastic bag. Place the bag in the sun and keep it warm, at a constant 65 to 70 degrees F. You will first see a layer of green goo on the surface of the pot. This is the primordial soup that will become new ferns. This can take a few days or several months. Next, small fern like structures will appear, when these fronds are about 1 inch tall remove the plastic bag. As the ferns are very closely packed they will have to be transplanted in clumps to small pots. Once they are two to three inches in height they can be transplanted to individual pots. Fertilize lightly at this time.

Problems:

Scales, mealybugs and mites are the most common insect problems. Avoid pesticide use as it may damage the plant. A hard spray with warm water will dislodge most insects. Hand picking can also remove these pests. If infestation is extensive and you must use a pesticide, carefully read the label for warnings about using the product on ferns.

Plant Selection:

When first growing ferns you may want to start with some of less demanding varieties such as Bird's Nest fern (Asplenium nidus), Japanese Holly Fern (Cyrtomium falcatum), Rabbit's Food Fern (Polypodium aureum) or Brake Ferns (Pteris cretica). Boston ferns (Nephrolepis exaltata) are a good choice if you can maintain the high humidity they require. If you want a challenge, try growing, Maidenhair (Adiantum), Staghorn (Platycerium sp.) or one of the potentially huge tree ferns (Dicksonia antartica).

By Cheryl Cadwell, URI Master Gardener