The swordferns (genus Nephrolepis) have erect fronds and are valuable for house use. The househollyfern, birdsnestferns, and spiderferns are also attractive and useful for indoor growth. Potted ferns may be summered out-of-doors in shady places protected from hard winds or rains. They may be divided and repotted at the end of their dormant seasons.
Extremely valuable and long-lasting as house plants. Like the landscape gardener selecting trees, however, the indoor planter must bear in mind the size to which palms eventually will grow. The Weddell Stevensonpalm, with slender leaves of green with silvery undersides, is an attractive feather palm for window display but cannot endure excessive dry air or direct sunlight or irregularities of watering. The pygmy Roebelen phoenix, of the palm genus whence comes the commercial date palm, is another graceful plant for the average-sized house. In using palms, be alert against scale insects.
English ivy is fine for potting and useful in chilly rooms, where it develops attractive winter colours of the leaves. The common form of English ivy is a good house plant, and some of the smaller leaved varieties are even better! The three similar plants of the Spiderwort family known as Wanderingjew are grown easily but require plenty of water. They are used principally for hanging baskets and outdoors as ground or bench cover. Probably the most useful of the asparagus group for home culture is asparagus springeri, which bears flat, spruce like needles. It requires heavy nourishment, moisture, and good light. Philodendron is another satisfactory house vine, as are the so-called ivyarum vines, which flourish in moderately lighted rooms with high temperatures. Venezuela treebine, colloquially called evergreengrape (Cissus rhornbifolia) may be used in a manner similar to the English ivies but in somewhat hotter rooms. All of these vines generally need uniform moisture, reasonable humidity, rich porous soil, and moderate summer sunlight.
Plants such as cacti, called succulent because they have thick, somewhat succulent or juicy leaves or stems, serving as a water storage system over dry or freezing periods in nature. Contrary to the belief of many that cacti are the vegetation of the starving, arid desert, many forms are grown because they are beautiful plants or producers of beautiful flowers. The needs of the cactus are as diverse as its forms are numerous, and for houseplants the sorts should be selected which can stand the limited, uneven light of the average window. The genus Opuntia, of which the prickly-pear is the most familiar representative, may very well be ignored for house culture. For considerable shade, such as in the apartment with northern windows only, species of Schlumbergera (also called Zygocactus) and of Epiphyllum offer worthy choices.
The general soil requirements for cactus are moderate richness and humus, excellent drainage, and some lime. The Agave genus, of which the century-plant (Agave americana) is a member, is an extensive plant clan, but most of its members are too large for the average home. Among the most useful of the smaller sorts are Agave victoriae-reginae, about 18 inches high, semi-spherical in form, with stiff, dark leaves marked with white and silver, and Agave parviflora, with narrow leaves, similarly marked, forming a rosette about 8 inches in diameter. The succulent genus Crassula offers several good-looking varieties for sunny windows. Some of the euphorbias are succulent and one of the best of these for indoor growth is Euphorbia lactea, which grows tall and erect with a three-sided, scalloped trunk and symmetrical branches, giving it something of the appearance of a signal tower with the arms pointing upward.
The South African succulent genus, known as Haworthia, has so many attractive and odd-looking forms that plants are frequently collected as a hobby. One group has almost translucent leaves and another has thick, dotted leaves. Like the haworthias, the apicras are selected for their attractive leaves and unusual growth habits. The gasterias, with their excellent foliage and green-tipped pinkish orange flowers, are also highly desirable plants for pot Culture. They need moderately rich soil, fine drainage, and little water during the winter but an increased supply during periods of flowering and new leaf formation.
The aloes, of which only the smaller forms are useful as house plants, need moderate temperatures, sunlight, free circulation of air, good drainage, and soil that is not too rich. In handling some succulents do not confuse them with extreme xerophytes, which are drought-defying desert plants. Many succulents demand timely and sufficient food and water, although they will stand to be neglected for a few days, depending on the species.