Haworthia (2021)

By Bob Williams (May 2021)

I am continuing our Plant of the Month series on plants that take up little space and are somewhat easy to grow, readily available and somewhat inexpensive. In researching plants that meet these criteria, the genus Haworthia falls into this category. Several members of the club have been growing these plants for an extended period of time and can provide good advice on how to grow them.

Haworthia is a genus within the family Asphodelaceae, subfamily Asphodeloideae. The genus is named after the entomologist, botanist and carcinologist Adrian Hardy Haworth (1767-1833). What is a carcinologist, you may ask? That is a person who studies crustaceans. Haworth never traveled outside England, yet published seven botanical books, an entomology book and 25 entomology papers. He also helped found the Entomological Society of London.

Prior to 2012, there were 276 accepted species of Haworthia in addition to a large number of hybrids. In 2012, the botanical community started to reclassify the plants in this genus. Many species of Haworthia have been moved to Haworthiopsis and Tulista. As of February 2018, there were only about 60 species classified as Haworthia.

Most Haworthia species are endemic to South Africa, with the greatest number found in southwestern Cape. Some species do, however, extend into neighboring territories of Swaziland, southern Namibia and southern Mozambique. These are areas that are hot and dry, with distinct rainy seasons.

In habitat, haworthias tend to grow under bushes or rock overhangs in poor sands and rocky areas. They generally resemble miniature aloes, except in their flowers, which are distinctive in appearance. The small, low-growing plants form rosettes of leaves from 1 to 12 inches in diameter, depending on the species. These rosettes are usually stemless, but in some species, stems reach up to 20 inches in length. The flower cluster comes from the center of the plant and may grow to 16 inches in height.

Haworthias can grow solitarily or form clumps. Many species have firm, tough, fleshy leaves, usually dark green in color, whereas others are softer and contain leaf windows with translucent panels through which sunlight can reach internal photosynthetic tissues. Their flowers are small and generally white with green or brown striations. Leaves can show wide variations within the same species as to patterns, warts or bands. When the plants are stressed, they can change color to reds and purples. Identifying a species by leaf characteristics may not be reliable.

These plants are not considered difficult houseplants to grow. As with all succulents, the most dangerous situation is too much water. Haworthias should never be allowed to sit in water under any circumstances.

Haworthia species like bright light, but not direct sunlight. They grow in conditions similar to those of other succulents. They do best in a room with a window facing east or west to provide bright light for a few hours a day. White or yellow leaves usually signify too much sun. If a plant isn’t getting enough light, its green color will fade. If you move your indoor plants outdoors for the warmer months, ease a haworthia into more and more direct light per day or it may sunburn. Bright, indirect light is the best.

It should not be surprising that these plants require a fast-draining soil mix. Water evenly and generously in the summer, letting the soil media dry out between watering. In the winter, reduce watering to every month or six weeks. Never allow water to collect in the rosettes.

Haworthias like higher temperatures in the summer, but coolness in the winter. During the winter, they need to be in an area that does not get below 45 degrees F. These plants are slow-growing, so repotting is not an annual occurrence. They can remain in the same pot for many years. Most of these plants send out offsets forming small clusters, similar to those of aloes and gasterias. The main way to determine if it is time to repot is when the cluster fills up the pot in which it is growing.

When repotting, you can take some of the offsets and plant them. These offsets will have roots, so try to take as many roots as possible when planting. I like to dust offsets with some rooting hormone, but that’s just me. Wait a few days before watering the new plants.

I have three Haworthia plants in my collection that I will describe. The first one is H. fasciata, more commonly called the zebra plant because of the leaf coloration. This is a very common plant that can be found almost everywhere. Places that sell succulent container gardens frequently include this inexpensive plant. In the photo, my plant still shows signs of sunburn from previous years. As the plant grows and sends out offsets, the older leaves tend to die off. Over time, these sunburned leaves go away. This plant has been in this pot for five or six years.

I also have a hybrid named Three-Cornered Hat. This plant was purchased in 2013 and has been in the same pot since then. I may need to repot it and refresh the soil mix. The close-up of the flower shows its green striations. The plant will send up the flower stalk with multiple flower buds. The lower buds flower first and it will flower up the stalk over several weeks. After the flowering is complete, the stalk will dry and can be cut.

The last plant is H. longiana, also pictured. This is one of the more interesting species within the genus, at least in my opinion. In habitat, this plant is found in the Eastern Cape region of South Africa. It grows in valley bottoms and on lower stony slopes of hills hidden among sparse shrubs and
grasses, but often in full sun. The plants are frequently grazed by herbivorous animals.

H. longiana is a tall, stemless grasslike plant that looks like a miniature agave. It can assume huge proportions by haworthia standards – up to 12 inches tall – but the length and slimness of leaves are variable from plant to plant depending on clone and origin. Some forms can be unbelievably slow-growing, producing no more than one or two leaves a year, and can remain in a 4-inch pot for decades.

As you can see from the picture, the tips can show some dying. This plant is slightly more prone to rot, so slightly less watering is recommended. Otherwise, follow the growing instructions described above.

As I have said, haworthias are readily available. Stores like Lowes and Home Depot usually carry a variety of these plants, but don’t buy the blue or red ones, only the natural ones! Any nursery that sells succulents will also have haworthias for sale. Another resource for plants is the annual Huntington Botanical Garden ISI Plant Introduction sale. Every year, the Huntington sells cacti and succulents that have been propagated by its staff. The prices are reasonable.

If you want to expand your collection and are looking for hardy plants that don’t need repotting every year, consider haworthias.

Sources:

Huntington Botanical Gardens – International Succulent Introductions –
http://media.huntington.org/ISI/catalogintro.html#c atindex
The Spruce – How to Grow Haworthia Indoors –
https://www.thespruce.com/grow-haworthia-succulents-1902980#:~:text=Haworthia%20Plant%20Profile%
20%20%20Botanical%20Name%20,%20Part%20su n%20%206%20more%20rows%20
Wikipedia –
https://en.wikipedia.org/wiki/Haworthia,
https://en.wikisource.org/wiki/Haworth,_Adrian_Hardy_(DNB00)
Llifle Encyclopedia of Succulents –
http://www.llifle.com/Encyclopedia/SUCCULENTS/Family/Aloaceae/21351/Haworthia_longiana
The Plant List – http://www.theplantlist.org/tpl1.1/search?q=haworthia
The Haworthia Society – https://www.haworthia.org