Ferns do best with indirect lighting. A north-facing window is
ideal 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-facing
windows, as the intense sunlight may scald the leaves or fronds of the
ferns, depending on the intensity of the light. Or they may dry out
faster 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 during
the day, up to 10 degrees cooler at night. If temperatures exceed
75 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 more
tropical ferns may grow poorly, preferring the higher temperatures.
Consistent watering, keeping the soil evenly moist, not wet, is also
key to the health and well being of the plants. Over watering causes
the fronds to yellow and wilt and may eventually lead to root rot and fungal
diseases, especially if the pot is allowed to sit in water. Too little
water also causes wilt. A few varieties, such as Rabbit's Foot Fern,
Brake ferns, and Holly Fern are an exception to the consistent watering
rule. For these, you may allow the soil to dry out slightly between
watering's.
Ferns, many of which are native to the tropics, like high humidity,
which is why they do well in bathrooms. But you also can increase
humidity 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 touch
the water in the tray. The evaporation will add extra humidity around
the plants. The best solution is to have a room humidifier adjacent
to the plants. This also benefits people indoors in dry homes as
well. Homes often have five to 10 percent relative humidity.
Humidifiers might raise that to 30 to 50 percent, which is really minimum
for 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 main
container into a second, larger container that you have lined with moist
sphagnum moss. Keep the moss moist or even wet. Use plastic
pots, which don't dry out as quickly as clay pots. The latter are
not recommended for many ferns indoors, unless you use the pot in pot method
as described above. A clay pot surrounded by moss then the ceramic
or plastic pot on the outside is probably ideal.
In addition, misting the foliage, especially in winter, will increase
the humidity. Just be careful not to mist the furniture and outer
walls. 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 will
brown or die back. Maidenhair, Stag horn, and Boston Fern are especially
susceptible to lack of adequate humidity.
Ferns require only light feedings of fertilizer once a month from April
through September unless actively growing in winter months. Apply
liquid houseplant fertilizer at about one-half the recommended rate.
Too much fertilizer will scorch the foliage. Newly potted plants
should not be fertilized for four to six months, again unless there are
indications of active growth.
Plant diseases are rare in ferns grown indoors although your plants
may suffer from infestations of scale insects, mealybugs, and mites.
Handpicking or spraying with water are the best options for control as
pesticide sprays may injure ferns. If you must use, choose the least
toxic product for the pest and read the label carefully before applying.
Check at least weekly to catch pests early. If ferns are infested
with 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 before
the rest of your houseplants are affected.
Ferns will require re potting every few years. Re pot in the spring,
using a purchased soil-less mix that is 50 percent peat moss. Divide
overcrowded plants by removing from the pot and cutting carefully between
rhizomes (fleshy roots). Keep as many leaves as possible per division.
It is also possible to propagate new plants by spores. In the
summer plants will produce spores (brown dots) on the undersides of the
leaves. When these spores darken, remove the leaf and place in a
paper bag. As the leaf dries out, the spores will fall off.
Plant in a peat-based seed starting mix. Water well, and place in
a plastic bag. Temperatures of 65 to 70 degrees will encourage sprouting.
When fronds are one-inch high, remove the plastic bag and transplant
in groups in small pots. At two to three inches, transplant to individual
pots. This can be tricky as it often takes quite a while for fronds
to reach transplant height, and moss and algae or other growth may appear
first and kill off young plants, so be forewarned if you decide to propagate
your own ferns.
The following ferns can be grown as houseplants. Or ask your local
garden center for recommendations.
--Birds nest Fern (Asplenium)--one of the easiest ferns to grow;
may reach 18 to 24 inches tall although in humid room like greenhouse
might 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's
nest. At Botanica Gardens we have so many new varieties to choose from as well.
--Boston Fern (Nephrolepis)--also known as the ladder or sword
fern; has long, delicate fronds and light green foliage; grows from 10
inches to three feet, depending on cultivars; ideal for hanging baskets;
fern may drop leaflets, especially if too dry, making this a "messy" plant
to grow; some newer dwarf compact cultivars are an excellent choice for
a houseplant. These were especially popular in Victorian times.
--Brake Ferns (Pteris)--several varieties are available, including
some with variegated foliage; may be grown as a table fern or in a hanging
basket; prefers diffused light and nighttime temperatures of 50 to 55 degrees
F, 68 to 72 degrees F during the day.
--Button Fern (Pellaea)--good plant for small spaces as it only
grows 12 to 18 inches tall; it is often dark green and has round, slightly
leathery "button-like" leaves attached to slender stems.
--Holly Fern (Cyrtomium)--also known as the fishtail fern; has
bright, glossy, leathery leaves; rather unfernlike in appearance; prefers
cool to moderate temperatures and indirect sunlight; requires less humidity
than most other ferns; ideal for lower light conditions.
--Maidenhair Fern (Adiantum)--fast-growing fern that needs high
humidity and consistent moisture to survive; foliage is lacy with small,
fan-shaped leaves; does best in a north window. If it dries out, the foliage
may 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 hanging
baskets as the furry, creeping rhizomes hang over the edge of the container,
resembling a rabbit's foot; needs to be planted with rhizome above soil
level instead of buried; very sensitive to salt and thus needs to be watered
with soft water.
--Staghorn Fern (Platycerium)--leaves are wide, flat, down-covered,
and resemble an elk's antlers; slow-growing but can reach three to four
feet in height; should be grown in sphagnum moss with the shield (the brown
part from which the green "antlers" emerge) wired to a piece of wood or
cork bark; fern is really marginal in many interiors as it needs lots of
humidity; water by taking entire wood slab or cork bark and moss off the
wall or wherever it is hanging, then immerse with plant shield into a pan
or tub of water. A bath tub without soap suds works best. Water
should be lukewarm, not hot. Allow to drain before rehanging.