Epiphyllum and lithops are two types of unusual indoor house plants, and also largely misunderstood. Both are succulents, and as such have light and watering requirements that differ from many other types of house plants. Epiphyllums, for instance, need less sunlight than one might expect; lithops, on the other hand, loves strong sunlight but has distinct watering needs.
Technically a type of cactus, epiphyllum is an indoor house plant popular for its unusual evergreen leaves and rare but strikingly beautiful flowers. Known commonly as the "orchid cactus," epiphyllum plants bloom during late summer or early fall under the proper conditions, unfurling large, fragrant blooms up to 8 inches across---but only at night. Epiphyllums are epiphytic, meaning they use aerial roots to absorb moisture from the air and climb a supporting structure. After flowering, plants produce edible fruits.
Care and Culture
Epiphyllums are propagated primarily by cuttings, as the flowering cycle is naturally very rare and can be difficult to induce under indoor growing conditions. Cuttings should be allowed to dry out for about a week, after which its base should be dipped in rooting hormone and the cutting planted in a moist potting mix. Established plants grow best in a warm environment under filtered light and may burn when exposed to strong midday sun. Root-bound plants are more likely to bloom than those with minimal roots; these plants should be exposed to cool temperatures for several weeks in the winter, around 40 degrees F. Sustained exposure to temperatures below freezing can kill the plant or force it into dormancy.
A native of South Africa, plants of the Lithops genus are also commonly called stone plants or living stones for their strong resemblance to smooth, stubby pebbles. In nature, plants are remarkable for their tendency to adopt the surrounding color scheme, thought to be a defense against herbivores. During the mid-year rainy season, each plant bears a single fragrant flower which strongly resembles the bloom of a daisy.
Care and Culture
Lithops species can withstand a fair amount of heat and drought and can be grown outdoors during the summer months in the Northern Hemisphere. As a container plant, the growing medium should be allowed to completely dry out between waterings, as over-watering virtually guarantees root rot and plant death. Abstain from watering at all during the plant's natural dormant period, from fall until spring, during which time lithops usually produce a new pair of leaves and drop the old set. Plenty of bright light during the spring months increases the likelihood that plants will produce a flower in early fall.
Virtually no pests or diseases trouble either epiphyllum or lithops species, making them some of the most insect- and disease-free houseplants available. The primary causes of death or unsightly damage are due to improper light or watering, particularly with lithops, which can die very rapidly if watered at all during its dormant period. Epiphyllums will develop yellow or brown speckling on the leaves if exposed to direct midday sunlight during the summer months; moving plants to a location where they are protected from bright light is the main remedy.