Wisconsin Horticulture
If you’re like me and enjoy the challenge of growing houseplants and getting them to thrive, then Ourhouseplants can help. This website shares my knowledge and years of growing plants and provides (hopefully) helpful advice on properly caring for your indoor plant friends.
Haworthia (Zebra Cactus / Pearl and Star Window Plant)
Haworthias are dainty succulent houseplants and are frequently compared and confused with Aloes, and Gasteria plants, this is hardly surprising since they’re all members of the Asphodeloideae family. However, unlike Aloes, Haworthias are almost always small and very (very) slow growing plants.
They don’t need much fuss or care and can even go many weeks without water if required. They also tend to look brilliant in unusual containers or interesting soil mixes.
Whilst Haworthias are normally small plants, they can still make a huge impact
These perks mean they can make fantastic easy care gifts and presents for all types of people, suiting either a home or an office environment. They’ll get by with not a great deal of fuss or attention provided they’re placed in a room with average warmth, away from direct sunlight and given the occasional drink.
As well as being very easy going houseplants to have around, when it comes to picking out a Haworthia there’s a vast number of different varieties to choose from. Some of the more commonly found ones are described below.
When it comes to picking out a Haworthia there’s a vast number of different varieties to choose from.
H. limifolia has ridged and normally more triangular chunky firm shaped leaves. They have prominent solid ridges that line the outside of the leaves (last picture in the gallery and the first plant in the photo below).
Perhaps the most popular varieties are H. attenuata and H. fasciata, both are commonly known as the Zebra Cactus. The white wart-like tubercles cover the back of the leaves often in a stripy arrangement which resembles a Zebra stripe pattern (the first photo in the article above and the middle plant in the photo below).
A lot to take in? – There are a huge number of varieties out there to buy. If you’re not sure what you want (or already own), check out our photo gallery. You can also share a photo of your plant in the comments below.
H. margaritifera or the Pearl Plant has slightly wider leaves and the “warts” are more dotted and spaced out producing a “pearl” type of effect.
H. tessellata or Star Window Plant is the other Haworthia you’re likely to come across, instead of white warts, the ones on this plant are semi-transparent “windows” (see third gallery picture to the right and third plant in the photo below).
Three different types of Haworthia Plants – H. limifolia, H. attenuata and H. tessellata
All healthy plants will eventually produce flowers, usually a few weeks after the “longest day” of the year, i.e. in Summer. However the flowers aren’t very exciting, but because Haworthia is a very slow growing and compact plant, not much happens visually during the year, therefore the flowering period can be a welcomed treat to show that your plant is actually “alive” and doing well.
That’s the introduction covered so scroll down for the full care instructions for your Haworthia plant.
If you’re like me and enjoy the challenge of growing houseplants and getting them to thrive, then Ourhouseplants can help. This website shares my knowledge and years of growing plants and provides (hopefully) helpful advice on properly caring for your indoor plant friends.
Haworthia Photos
Haworthia Step by Step Care Guide
Light
Haworthias are reasonably adaptable plants that that will take various light conditions, but neither direct sunlight nor deep shade. Direct sunlight will make the leaves of all Haworthia’s go an ugly red, purple or brown colour. Move to a shady spot and if the damage isn’t too bad these colourings will fade over time.
Light
neither direct sunlight or deep shade
Deep shade tends to weaken the plant over a prolonged period. You might notice it becoming an excessive light green, losing the markings or that the plant stops being compact and instead becomes lanky. If you notice this happening more light is needed.
Watering
A surviving plant will get by with watering just once a month, however to get the plant thriving it will need to be done at least once a fortnight, possibly once a week in very warm temperatures.
Either way, water well and then only water again when the soil has largely dried out. These plants are very tolerant of underwatering but will succumb quickly to rotting if overwatered.
Make sure you try your best to keep water out of the crown or rosette of the plant, in cool temperatures doing this will again encourage rotting.
Their thick leaves mean they can store water and will cope if you forget to water them for a while
Humidity
As is common with many other succulent plants humidity is not important. However, they do like good ventilation so avoid very tight “airless” corners of your home.
Feeding
Feed your Haworthia very occasionally and when you do, ensure it’s only a weak solution. Feeding two or three times a year is probably plenty. Plants that are producing massive numbers of offset around its base might benefit from a little more feed, but still, go easy as they’re not big feeders.
Temperature
Average indoor warmth between Spring and Autumn / Fall. The natural cooler temperatures found in an unheated or guest room during Winter are perfect because this plant likes to rest at that time of year. However, it doesn’t like being too cold and absolutely no lower than 4°C (40°F).
Repotting
It’s rare for any Haworthia to outgrow its pot quickly, therefor repotting is only usually required infrequently and normally only when offsets have filled the pot. Sometimes the clump works itself free, becomes unstable and starts falling out of the container so you’ll have to repot to get it stable again.
You only need to think about repotting when the plant has started to fill the pot with offsets, as shown here
If you do find yourself needing to repot your plant, use a similar soil composition to what was being used previously. Normally this will be standard houseplant or cactus compost with grit or perlite added to aid in drainage.
If you divide the plant and remove a number of the offsets to reduce the overall size of the clump you can probably just reuse the existing pot / container. If not, just choose a pot slightly bigger than the last.
Propagation
When you repot your Haworthia you can separate the offsets from the parent. Use a sharp knife and cut as close to the parent plant as possible, ensure the offset has some roots. Sometimes a knife isn’t even needed as the offset will be loose like a wobbly tooth and just come away naturally with a small tug. Just don’t be too aggressive!
No roots or you were too aggressive? – I’ve accidentally knocked out larger plants from a cluster before, with the roots still left behind with the rest of the cluster. Whoops! If this happens to you, don’t sweat it. As long as the base is intact, you can simply pot it up in a container of moist compost and it will grow new ones in a matter of weeks.
Wait a day for the offset to dry slightly this reduces the chances of the raw “wound” from rotting when added to compost. Then pot up in a small container using a standard potting or cactus compost mix. Water and keep warm.
In my experience, I’ve had much better success by doing this at the end of Spring or during Summer when it’s both warmer and lighter.
Speed of Growth
Expect slow growth. Although some of the fleshy more leafy varieties such as H. margaritifera or the Pearl Plant grow quite a bit faster.
Flowers
Yes, this is a flowering houseplant. The flowers will normally appear in Summer months on the end of a long stem (inflorescence) if they’ve been treated well during the year. If you want to see what they look like, be sure to check out our readers’ photos in the comments section further below.
Height / Spread
Haworthia is a small plant by design and anything from 4 cm (2 in) to 20 cm (8 in) in height is usual. The flower stem though can be quite substantial in length.
This is a pretty narrow and slender plant, but it spreads and multiplies easily through offsets so individually they aren’t very wide, but if left alone they will form a clump within a few years. The photo below shows what, at first glance, looks like just one plant, but if you look at the base you can see it’s actually two individual plants.
Over time this Zebra Cactus has divided and there are now two plants growing side by side
Are Haworthias Poisonous?
As well as all the other positive traits about the Haworthia, another bonus is that it’s not poisonous to people, cats or dogs.
Anything else?
These plants are compact but when treated correctly they do produce offsets quite easily.
This means the plant will spread and grow into a clump, so one solo plant at the start will quickly become many which in turn will eventually fill a pot to add some impressive visual appeal. You can let the clump continue to grow and spread within the existing container, or separate them for even more plants.
How to Care for a Haworthia Recap
- Moderate Light Levels Avoid direct sunlight and very shady areas.
- Moderate Watering Once a week or so in Summer and once every two weeks in Winter.
- Temperature Normal indoor room temperatures. 10°C (50°F) to 29°C (85°F)
- Feeding Try to fertilise once every three months when it’s growing.
- Doesn’t like to be overwatered
- Won’t tolerate cold temperatures
- Keep out of direct sunlight
Haworthia Problems
Leaves going red
This also happens with the Christmas Cactus, and it occurs when the plant is being exposed to direct sunlight i.e. it’s getting too much light. Find it a new home which is slightly darker, or provide shading. In a few weeks, the red should start to fade and look normal again.
Black spots / Areas
Usually caused by overwatering, or when water is allowed to pool in the crown or between the leaf voids. The plant is basically rotting. Increase the intervals between watering, and ensure it’s not sitting in water for prolonged periods.
This has likely been caused by a damaging combination of overwatering and exposure to cold temperatures.
Cold temperatures or overwatering can easily cause this to happen
Remember that Haworthias are warmth loving houseplants with only moderate watering requirements. It could be easier to think of them as Desert Cacti when it comes to their needs in these areas. Just without the intense sunlight otherwise you’re causing a different problem!
You will have to use your own judgment here. Wrinkling leaves on a Haworthia are normally caused by either no water for a prolonged period or too frequent watering. If you look back on how the plant has been watered over the last few months you should be able to judge which is the cause and adjust.
If you’ve got a brand new plant and it’s already come like that, you could take the plant out of its pot and examine the soil and feel the moisture level.
Brown dead Haworthia leaf tips
This is one of our most popular questions. I would point out that in most instances some degree of leaf browning is normal. Your plant might have accidentally had its tips knocked at some point, or it’s placed in an area with very dry air, such as near a heat source like a radiator.
You could try moving your Haworthia to a new home to prevent further browning, especially if it’s quite disfiguring. But in all likelihood, the damage in most cases is confined to the very tips of the leaves and it could just be a case of not needing to do anything other than snipping the brown ends off.
Our Story with the Haworthia
By themselves, these are fairly standard plants. Undemanding and easy yes, but the pay off is that they don’t grow very fast and at times can have an almost artificial and alien look about them. I do understand why they’re not for everyone, but they do have some seriously passionate fans and get a lot of love (check out the comments below).
Initially, they caught my eye simply because shops were selling them in funny shaped containers. Or planting them up in quirky and unusual soil compositions (for example the ones below are growing in sand and small white stones).
Much like the current Air Plant trend, I felt it was all very unnatural. Basically all that was missing was a sticker summarising everything the sellers had put together by simply saying “I’m cute. Buy me“.
In the right pots, these plants will truly shine and add style to your home
Eventually, I caved to the “cuteness” and brought a few that were on sale (see above). They grew on me slowly. I’m struggling to explain why, as all the negative points about them are still present. I think in many ways the uniqueness of these houseplants is that they add a subtle but bold architectural statement to your home that gradually draws your attention without being over the top about it. They wait to be noticed rather than scream for attention. I like that.
Then they go quiet and almost vanish from your sight for weeks, they don’t demand anything and just blend into practically any growing location. Catching your eye once in a while and it’s like discovering them all over again.
I honestly can’t remember a time when I didn’t have a Haworthia or two growing in my home
Since I brought my first ones I honestly can’t remember a time when I didn’t have a Haworthia or two growing in my home. They grow steadily and the offsets come lose quite easily so it’s very easy to propagate new plants (I’ve easily given away more of these plants than Spider Plants).
They’ve been a solid staple in my indoor plant collection and for good reason. Haworthias are plants I’d seriously recommend that beginners try and experienced houseplant owners need to own.
Haworthias – Super Succulents for Small Spaces
Haworthias are small and deservedly popular succulents from southern Africa. They are generally of easy culture, of small and convenient size, more tolerant of modest lighting than many succulent plants, and come in many beautiful variations on a common theme. Though the small whitish flowers are less than spectacular, they are rewarding and very willing to come forth under diverse conditions. The real glory is in the succulent leaves, which, depending on species, can be variously colored in greens, reds, or browns (to near black). Some have leaves that are thin and bristly, others thick and fat. Some are plain, others are marked with lines, bumps, stripes, or dots. All these factors point to why Haworthias are very popular houseplants capable of being grown successfully indoors in all areas of the world, and outdoors where frosts are infrequent and of short duration. Many Haworthias readily offset and therefore are easily passed along to friends or handed down from generation to generation.
What’s in a name – Haworthia
Many genera and species of plants are named after people; succulent plants are no exception. The genus name Haworthia commemorates Adrian Hardy Haworth, an accomplished British botanist and entomologist, who was born in 1768 and died in the London cholera epidemic of 1833. As an entomologist, Haworth is best known for his work on Lepidoptera (butterflies and moths). As a botanist, he is best known for his studies of succulent plants of diverse families (including New World cacti in his later years) and bulbs. Haworth named many new plant genera and species, though some of his names have been lost over the years due to taxonomic refinement. Two of his genera that remain and are well known and beloved groups to cactophiles include Mammillaria and Epiphyllum. Haworth has had several plants named after him. In 1809, the new genus Haworthia was created by the Frenchman Henri Duval in honor of Haworth. Prior to the creation of the new genus, these plants had been considered part of the genus Aloe.
The first written references to Haworthias go 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 and they have probably been in cultivation there for nearly 400 years. They are readily available from home stores, garden centers, even the floral section of grocery stores; rare and unusual oddities are available from succulent plant nurseries. In Japan, where horticultural uniqueness commands high prices, Haworthias with special markings, forms, or colors can sell for hundreds of dollars; more common but equally appealing forms usually cost just a few dollars. Because they stay small, a nice representative assortment can fit comfortably onto a windowsill. They are easily grown as houseplants in Wisconsin and, during the frost-free period, can add to the décor of the patio table or the garden bench. 
Haworthias are native primarily to the country of South Africa, with a few species spilling over the borders of neighboring countries. They are closely related to aloes and are in the aloe family, Aloaceae. At one time, up to not too long ago, aloes, Haworthias, and their relatives were considered part of a very large lily family (Liliaceae) which has rightly been broken up into more meaningful units. However, older reference books will show Haworthias to be in the lily family. Two other related smaller genera are Gasteria, with red to orange flowers and about 15 species, and Astroloba, with about 10 species that have an elongated, columnar form. 
Besides their ease of cultivation, two other factors have made them a favorite group of both succulent growers and those just generally interested in gardening and houseplants. The first of these factors is their great diversity in form, shape and color. While almost all are of a general rosette pattern (the fan-shaped H. truncata – photo at right – being the exception), there is endless variation in the details. Although there are disputes amongst the experts as to what defines a species in Haworthia, it is generally recognized that there are at least about 60 named species and about 150 named varieties. Additionally, there are differences in nature from one population to another and even two plants growing side-by-side in the same population can have quite different coloration or markings. Nurserymen have selected particularly attractive forms. Also, some enthusiasts are developing interesting and unusual hybrids.
The other factor that results in their popularity is their small size. Individual single plants are usually in the range of 1-3” in diameter and clusters of several dozen stems can fit nicely in a 4-5” pot. This allows for a diverse collection in a small space, such as on a windowsill or under a set of fluorescent lights.
Growing Haworthias 
Haworthias are easy to grow as long as you keep in mind that they are succulents and require the appropriate light, temperature, soil, and watering. Although it is possible to kill a Haworthia, they are generally forgiving of the occasional lapses of ideal care.
Light. The stereotypical image of cacti and other succulent plants is as desert inhabitants, living fully exposed in the hot, bright sun. Whereas large plants can survive such harsh conditions, many smaller succulents actually are found in the shade of rocks or shrubs. Although some Haworthia species can be found in full, bright sun, many live in more protected spots and therefore are adapted to thrive in partial shade (though few look their best without at least some direct sun or bright light). This makes Haworthias well adapted to lower light conditions found in homes. 
They probably do best in an east or west facing window where they get a few hours of direct light daily, and bright indirect light through the remainder of the daylight hours. A south facing window would also be acceptable but may be too bright for some species unless the sun is lightly filtered through sheer curtains. Haworthias do very well in sunrooms and greenhouses, though again many of them prefer to be located where they don’t get persistent direct sunlight, especially during the warmer part of the year. Haworthias grow very well under artificial lights, though they prefer more light intensity than provided by the standard fluorescent “grow lights.” A mixture of warm white and cool white bulbs gives both good light intensity and color balance.
The darker and more intense coloration and the very compact growth which many growers find most attractive are developed from brighter light conditions. In insufficient light, leaves will elongate and plants will lose the richness of their colors (see photo, right).
Haworthias make good accent plants on porch, patio, or deck and can be grown outdoors during frost-free periods. Be careful when you move plants outdoors. If they have spent the winter without much direct sunlight, don’t immediately put them into full sun outdoors or they may sunburn. Gradually move them into more direct light over a period of a few weeks.
Temperature. Some Haworthias can survive a few degrees of light frost for a short period, but it is best not to take chances. They do best in the temperature range of 75-90°F. But they can tolerate temperatures into the low 40ºFs, especially if they do not have continuously wet soil and they will survive high temperatures into the low 100ºFs, especially if they are somewhat shaded and have good air movement. 
Soil. Like most all succulent plants, Haworthias do not like their roots to remain wet for prolonged periods, so their soil mix should be well drained. A good commercial potting soil should be mixed with equal amounts of drainage material. Several options exist, including perlite (available in garden stores), aquarium gravel, poultry grit (available at feed stores and agricultural supply stores), or horticultural pumice (available at garden centers or through mail-order succulent nurseries). Do not use sand as it is too fine and clogs the pores in the soil. If using a peat-based potting soil, remember that peat decomposes in a few years, resulting in an unhealthy soil. As some Haworthias are slow-growing and can stay in the same pot for years, there may be a tendency to forget to repot into fresh soil, a practice which should be done every 2-3 years.
Watering. If the soil mix is well drained, Haworthias can be watered weekly in the summer months; less frequently in the winter. The soil should dry between waterings. Prolonged wet soil, especially when it is cool, there is low light intensity, and/or the plants are not actively growing can lead to root rot, a common problem with Haworthias. Symptoms of a weak or rotted root system include stoppage of growth, reduction in plant or leaf size, or leaf shriveling. Often though, root rot does not necessarily mean the plant will be lost. If the plant looks unhealthy, unpot it and inspect the roots. Remove any weak or decayed roots, even back to the stem of the plant. Allow the plant to lie out unpotted for a week, then repot into fresh soil and begin watering carefully until it is apparent that the roots have reestablished and the plant has regained its health. 
Remember that a healthy root system is the best method for removing excess soil moisture (through the transpiration process). Therefore, when repotting a plant, try to use a pot about the same volume as the root system. If the roots are diminished, or a larger pot is desired, just remember to water sparingly until the plants are reestablished.
It is difficult to generalize about the growing season of Haworthias. In nature, some come from winter rainfall areas and are winter growers, whereas others are from summer rainfall areas and are summer growers. For many species, the growing season is from late winter through spring (as the day length increases). 
Containers. Haworthias can be grown in virtually any type of container, including plastic pots, ceramic, or terra cotta. Terra cotta pots breath and release soil moisture faster than ceramic or plastic. Shallow pots are generally better than deep pots but some species have heavy, thick roots that ask for a deeper pot. Be sure that your containers have drain holes and, if you use saucers, be sure that you empty any standing water promptly. Also remember to use a pot that properly matches the size of the root system. Many Haworthias freely offset and eventually form clusters much larger than the individual plant. It is better to repot periodically as needed to provide additional space for the expanding plant rather than put a small plant in a large pot expecting the plant to eventually fill the container.
Because they stay small and have interesting forms, Haworthias are frequently used in succulent dish gardens.
Propagation. Vegetative propagation, especially by taking cuttings, is the quickest and most common method of propagating Haworthias. The majority of species cluster from the base; the new young plants are often referred to as offsets or “pups”. In many cases, as soon as the new young plants are formed by the parent plant, they develop roots. In some species, as soon as the new plant becomes well established, the original contact with the parent plant is broken; when the clump is unpotted, the individual plants fall away from each other. In other species, the attachment to the parent plant may remain; this can easily be broken or cut to separate the plants. If you create a subsoil wound during the separation process the plants should be allowed to air-heal for a few days before repotting to avoid the possibility of pathogenic organisms moving from the soil into the fresh wound.
Another method of vegetative propagation is used for those plants that never or only rarely offset. In such cases, individual mature leaves are carefully cut from the stem, along with a slight bit of attached stem tissue. Once the wound has dried, the leaf can be put into a well-drained soil medium and, in many cases, one or more new plants will slowly form from the severed leaf. This practice is not commonly employed by the average hobbyist but experienced nurserymen use it to propagate rare or slow growing plants. 
Haworthias can also be readily grown from seed, though seed is not commonly available except through specialist dealers in succulent plant seed. Seed should be sown in a well-drained soil mix and the soil kept moist until germination, usually within 1-2 weeks. The soil should not be allowed to dry significantly while the young seedlings are getting established.
Pests and diseases. Haworthias are generally free of most pests. The one exception is mealybugs, which can be a common problem but easily resolved by physical removal or with standard houseplant insecticides. The most significant disease problems are root rots caused by poor soil or too much moisture. Occasionally such root rots can move into the plant stem resulting in the death of the plant.
Sources
Because Haworthias are popular with the general public and are easy to grow, they can often be found in stores that sell an assortment of succulent plants, including the large chain home and hardware stores. Most better garden centers will have a selection of succulents including a couple types of Haworthias. However, to assemble a truly representative collection, or to acquire some of the rarer or more interesting forms, consider shopping at some of the specialty cactus and succulent nurseries. 
– Dan Mahr, University of Wisconsin – Madison
Thanks to Wolfgang Werk for the loan of plants for photographic purposes.
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