Dry Air is Murder on Ferns
by Don Janssen, Extension Educator
A Boston fern that's green and gorgeous when you bring it home won't stay that way long unless you can meet its need for humidity.
Dry air is the biggest obstacle to growing ferns as houseplants. Many ferns will do fine in typical indoor temperatures and bright light, and some will survive even in low-light situations, but they won't compromise on humidity. In dry air, the tips of the fronds will become dry and brown.
Using humidifiers to increase the moisture levels in one room or the whole house benefits not only ferns but also parched nasal passages, glued joints in furniture, and cats and people who walk on wool carpeting, but this tends to be the most expensive alternative to dry air. There's an initial outlay for the equipment, the cost of the energy needed to operate it and, with room units, a certain amount of tending required to keep them functioning.
How successful attempts to humidify the air can be depends to some extent on the number and type of windows in a room or house and the presence of other cold surfaces that can take water out of the air as fast as a humidifier adds it.
A low-cost, low-tech approach is simply to put ferns in an area of the house where humidity levels are naturally higher, such as a bathroom or the kitchen.
Double-potting plants is another way to add moisture to the air around them. To do to this, set the plant pot inside another, larger container and fill the space between them with peat or vermiculite and add water as needed to keep it moist. Setting individual pots or groups of plants on a tray of wet gravel accomplishes the same thing -- creating a moist microclimate around plants.
Misting plants produces only a temporary increase in humidity. Even misting several times a day has little benefit, and keeping the foliage wet this way can even promote disease development.
If you can provide the necessary humidity, a number of ferns will thrive under home conditions. Popular ones for indoor gardening include the Boston, maidenhair, sword, bird's-nest, feather, button and staghorn ferns. The staghorn fern can be grown either in soil in a pot or on osmunda fern roots fastened to a slab of wood hung on the wall; the others prefer a soil containing at least 50 percent organic matter that's kept moist but not soaking wet. They need protection against temperatures below 50 degrees and do best near a sunny window where they can receive direct light in winter and indirect or filtered light in summer.
The brown spots that develop on the undersides of fern fronds are no cause for alarm -- these are sporangia, the structures that produce the spores by which ferns reproduce.
University of Nebraska-Lincoln Extension in Lancaster County is your on-line yard and garden educational resource. The information on this Web site is valid for residents of southeastern Nebraska. It may or may not apply in your area. If you live outside southeastern Nebraska, visit your local Extension office