Haworthia is an extremely popular plant among succulent lovers! It’s prized for its highly variable appearance and its compact nature. Commonly known as zebra cactus (although it’s a succulent, not a cactus), Haworthia is a genus (fig. 1) of plants that is shrouded in mystery. The first species’ classifications of Haworthia were completed by 18th century English botanists Haworth (named after him) and Baker.
Botanists and hobbyists alike have had (and currently do have) trouble classifying species of Haworthia. This is mainly due to the lack of sufficient information and the extreme variability of the plants (Bokelman 2016). Originally, Haworthia was considered part of a very large lily family (Liliaceae), grouped with its close relatives, Aloe and Gasteria. In current updates, the lily family is broken up into smaller, more specific families, so as of now, Haworthia is listed under Asphodelaceae (Mahr 2005).
As for the exact number of species of Haworthia, it’s still really up in the air. Some botanists and researchers claim that there are 70 species, while others say there are over 300. One of the main explanations for this discrepancy is hobbyists falsely identifying the many cultivars they breed as separate species. This misinformation has been carried along from grower to grower, until the nomenclature is completely out of whack. A quote from long-time Haworthia researcher, Bruce Bayer, really sums it up – “never has so much been written, about which so many know so little. Inadequate descriptions and erroneous naming seem to be the lot of succulent plant groups where the degree of amateur interest has greatly exceeded that of the botanist” (Bayer 1974). To this day, researchers struggle to identify Haworthias down to their species’ name.
Stay tuned for a future blog post explaining taxonomy and why it’s so important!
Taking a look at the history and native habitats of a plant can give you great clues for how it should be cared for in cultivation. Haworthia is native to southern Africa, and typically grows in the shade of rocks and shrubs. In nature, find them growing on mountains with steep inclines and rocky, loose, undeveloped soil (fig. 2). The first written references to Haworthias trace back as far as the early 1600s when European colonists were discovering the botanical riches of southern Africa. Early explorers took Haworthias back to Europe where they have probably been in cultivation for nearly 400 years. Popularity with collectors took off prior to World War II (Bayer 1999).
What does Haworthia look like?
A main reason that Haworthia has gained immense popularity among plant collectors is due to the fascination of its “shape, arrangement, compact neatness and marking of the leaves” (Bayer 1973). They tend to be small (3-5 inches on average with the largest ones nearing 20 inches), low-growing plants. They have fleshy, green leaves that store water (a main trait of succulents). The leaves are often covered with white spots or stripes and grow in a “continuous spiral about the stem” (Bayer 1973). Leaves may have pointed, blunt, or rounded tips. “Some may be firm and tough, while others are softer, leathery, and resemble translucent “windows” on their upper surface” (fig. 3). These “windows” reduce surface area and transpiration of the plant, but they make up for it through surface translucency which helps sunlight reach the deeper buried chlorophyll-bearing tissue for photosynthesis (Bayer 1974).
Flowers of Haworthia are what botanists would call “insignificant.” This is because the flowers are small and few between. Although, Haworthia is grown for its foliage, it definitely is very exciting when your plants flower. The flowers are generally “irregular two-tipped, small, white, tubular, and attached to a long flower spike which can be simple or branched” (fig. 4) (Vosa 2004).
Taking Care of Your Haworthia
In nature, Haworthia tends to grow in the shade of rocks or shrubs, so they have evolved to need partial shade. They like bright but not direct light, so they perform best in east or west-facing windows. If you notice the leaves on your Haworthia beginning to turn white or yellow, this could be a sign that it is receiving too much light. On the other hand, if your plant is not receiving enough sunlight, the green-ness of the leaves will begin to fade. If your plant is looking rough and you think it might want more water, try actually giving it more shade (Bayer 1974).
Overwatering is probably the number one cause of death of Haworthia. They are extremely sensitive to “wet feet.” The microclimates that Haworthia has adapted to are extremely various, so some species need vastly different care. For example, there are species from the southwestern Cape adapted to winter rain, while species from different areas are extremely averse to winter wetness. Of course, any Haworthia you bring home will act differently based on the conditions you provide (ie: house temperature, light exposure, potting medium, etc.). In general though, for the species that you will find in your average plant shop in the U.S., you should water only once soil has completely dried. If you are unsure if you should water, wait a week. It’s a lot easier to bring a plant back from underwatering than overwatering.
Plants are susceptible to death when exposed to temperatures 40(F) and under. If you bring your plants outside (which you definitely can), bring them in when temperatures reach 50(F) to be on the safe side. I have lost a Haworthia to cold before, and it’s a very sad loss.
Many Haworthias grow on mountain-sides in their natural state, often exposing them to harsh winds. As they evolved, they adapted to the wind and now thrive in windy locations. You can simulate wind by keeping a fan running on low near your Haworthias. This will provide the adequate ventilation they need, which will actually help prevent pests and keep them healthy (Bokelman 2016).
Haworthias grow well in virtually any porous, well-draining soil. A succulent/cacti bagged soil mix will work great. If you amend your own soil, make sure to add lots of perlite or pumice for proper drainage. A standard soil mix of 1:1:1 of sand, loam, and compost will work as well (Bayer 1974).
Most Haworthias produce thick, dense, and short roots, so they should be planted in wide, shallow containers. This makes sense if you think about how they grow in their natural habitat, oftentimes among rocks and shrubs with limited soil around them.
The growing season of Haworthia really varies from species to species and can change with the current habitat they’re growing in. Some are winter growers, while others put out most of their growth in summer and are dormant in winter. As a good rule of thumb, use a cactus/succulent fertilizer to fertilize Haworthia once in spring and then again once in fall. They are not big feeders at all, which is a result of the lack of nutrients in the soils they grow in naturally on harsh mountain sides (Bokelman 2016).
Haworthias tend to be pest-free, “with the exception of mealybugs and scale.” Mealy bugs look like tiny, fluffy cotton balls. You can “remove them with a q-tip dipped in rubbing alcohol”. Scale is a tan or brown insect covered with a waxy coating that looks like a raised bump; eliminate the same as recommended for mealybugs or apply a systemic insecticide (Bokelman 2016).
The most common way to propagate Haworthia is by separating and replanting the pups (new offshoot plants) that form from the mother plant. They can also be propagated by leaf cuttings, division, and seed, but these are less common for the household hobbyist and oftentimes do not survive. You can propagate them at any time of the year.
Thank you for reading! I am very excited to start this new series of “Succulent Showcase” to share scientific information about the succulents we love. Please follow us on Instagram or Facebook to know as soon as we post new articles!
Katie Plummer , Jack Frost Director of Marketing and Communications