Surprising(ly Stinky) Stapeliads

Originally printed in the February edition of the San Diego Cactus and Succulent Society newsletter.

Easy San Diego Growers

The genus Stapelia hails mainly from South Africa, as many of our favorite succulent species do. They’re generally low-growing, spineless, and have simple branches or simply stems that grow in mats or as small shrubs. When it comes to foliage, they’re rarely something to write home about, although there’s a certain alien-world appearance to the unusual stems that’s attractive in a way.

What attracts most growers to Stapelia isn’t the foliage – it’s the incredible blooms that give them their common name: Carrion flowers.

There are dozens of species in the genus, and at least 160 that were once classified in this genus but have since been given genera of their own – Huernia, Caralluma, Hoodia and plants in those genera are still often referred to as Stapeliads, despite no longer being classified in the genus.

Fragrant Flowers

The flowers of nearly all stapeliads and stapeliad-like plants do tend to smell like rotten meat, but depending on where you have them planted, the smell isn’t always overpowering or even particularly noticeable. If you stick your face right up next to them, they’ll definitely knock your socks off, but grown outdoors and in open spaces, the smell is rarely so strong you can’t walk near them. Even growing some in my greenhouse, the solution to the freshly opened bloom smell was to open the greenhouse doors and let it air out.

Stapeliads are pollinated by flies and similar carrion-eating insects, and here in San Diego they’re quite convincing to the common houseflies we have buzzing around. The houseflies often will lay eggs around the fleshy center corona of the bloom, convinced that the flower is actually a source of food for their offspring.

Flowers are short-lived, typically only lasting a day or two after fully opening. Species with larger flowers, such as S. gigantea, will develop buds that look almost like balloons as they gain size. While individual flowers last only a day or two (making it easy to clip off fading flowers and dispose of them), the plant itself will often flower profusely over a longer period of time, weeks or even months.

Growing Your Stapeliads

Some genera/species are trickier than others, but care is roughly the same.

As with most succulents, if you’re growing them in a pot, use well-draining soil. Closer to the coast, where humidity is higher and daytime highs lower, you may want to create a soil mix that’s as much as 50% pumice to 50% succulent soil. If you’re further inland, like me here in Escondido, I find most of them do better with more organic material in their soil. My Stapelia giganteas are in straight succulent soil (I use E.B. Organics, or more recently, I’m giving the Gnosis Nursery “Alchemy Blend” a try), and they’ve needed that much organic matter to have water readily available.

Your stapeliads can tolerate extremely dry conditions, just like most succulents, but for thick fleshy stems and profuse blooms, you’ll want to water yours more often. They also do better when given a dry dormant period that corresponds to the same time of year they’d be dormant in habitat – but unless you’re growing one of the less common species, chances are you can ignore the dormancy period.

This map of South African climates, with the key below describing moisture/seasons, should be a helpful resource to compare where your species of Stapeliad comes from and gain an idea of temperature and rainfall levels.  For most of South Africa, the rainfall season is during the hot summer months, with even the desert regions receiving several inches for a month or two. 

When in doubt – water less often. It’s much easier to rehydrate your plant than it is to try and save it from rot. For most growers, rot is the biggest threat to cultivation, so be cautious!

The biggest indicator that your stapeliads need water is if they’re starting to wrinkle and shrink, or if the arms are drooping like a sad houseplant. I find my Edithcolea to be a bit of a drama queen, drooping and getting a bit floppy if it’s thirsty, and my Hoodia parviflora also drooped precariously when I left it a bit too long between watering.

A little bit of fertilizer helps encourage prolific blooms, just as it does in your stereotypical flower garden. Fertilize when you water during warmer times of year, and I’ve seen the best blooms when I use half strength fertilizer nearly every time I water. I’ve used fish emulsion and a dedicated cactus fertilizer with equal success, but I will say people seem far more offended by the smell of fish emulsion fertilizer than any of my stapeliad blooms.   

Most stapeliads will blush a darker color when given more sunlight than they necessarily need, and some look more attractive with that protective blushing. When kept in brighter sunlight exposures, they tend to need more water for regular blooming, which is something to keep in mind.

If you’re in a part of the county that generally doesn’t get a frost, or if you do, it’s very light – try growing your stapeliads in ground! I have S. grandiflora, S. gigantea, and O. variegata all as in-ground plants and they are thriving in exposures that are often too hot for the pretty soft succulent hybrids that work well in arrangements. They also grow easily in a ground-cover like manner, so they work well around other plants that are more sculptural.

If you need a divider between yourself and a particularly unpleasant neighbor, you can always use them as edging between yourself and said neighbor. Might I also suggest some Voodoo lilies for summer blooms to offset your winter carrion flowers?  

Propagation

I’d be remiss if I didn’t comment on how easy it is to propagate most of these species. They can be grown readily from cuttings for exact clones of the parent plant, or you can pollinate them to produce huge seed pods. The seed pods look almost identical to a Plumeria seed pod (if you’ve seen one of those), but failing that, they’re almost a jumbo-sized green bean that slowly darkens as they ripen.

For easiest growth when propagating from cuttings, take your cuttings in spring, as the weather is just warming up. They can be lain flat on succulent soil and may produce roots that way, as my Orbea variegata do constantly. Some species seem to do better when their cut ends are allowed to callous over, and then placed directly into damp soil or a 50/50 mix of soil and pumice. When waiting for roots, avoid watering much if at all. The rooting medium should be damp, at best, and misted or splashed with water to keep the soil from turning into dust until the cutting has firmly rooted. Just as with rooted plants, when in doubt, skip watering for at least a day or two.

You’ll know your cutting is rooted by gently wiggling it: a rooted cutting will feel like it’s “grabbed on”, while one that hasn’t will feel about the same as it did when you first put it in the soil. If you can’t feel a difference, it’s probably not rooted yet. Just don’t dig it out to stare at it! You’ll break or damage any baby roots that have tried to come out.

The Easier to Cultivate (And Easier to Find) Species

The species I’ll list and highlight here share one thing in common: they’re all easy to grow! Compared to some species which have very specific requirements, these are easy enough to use as landscape plants or stick in a container. 

One of the most striking and well-known species in the genus is Stapelia gigantea, with flowers that can reach over 1 foot in diameter when fully open! These, like many of the Stapelia blooms, can and will grab the attention of even the non-gardeners in your family with their “Demogorgon head” looking blooms. This species is also the worst, in my experience, for attracting flies that lay eggs – if you want to avoid that but still find the flowers fascinating, select a species with smaller blooms. Flowers are fairly consistent, being extremely large, red and yellow banded, always star-shaped and 5 petaled, although flukes can and do occur. Shorter daylight hours in fall and early winter trigger blooming. 

A very similar species but with smaller flowers is Stapelia grandiflora, with blooms that vary in shape, color, and size. Some growers have selectively bred this species for specific bloom colors, and you can find them ranging from a deep, almost black-red color to a striped pale pink-red with yellow bands. Smaller size of blooms means smaller smell and less chance of flies arriving, but these can be large enough to attract them anyway.

Not a “true” stapeliad, but one of the genera that was split out from Stapelia a while back, Edithcolea grandis (aka Persian Carpet Flower) is extremely popular, and for good reason! The flowers are of a decent size, up to 5” across, and striking enough to make most people stop and do a double take. The flowers typically have a yellow base, with red spots/edging and a complex pattern that almost resembles the Persian carpets that give them their name. Compared to the plants in the Stapelia genus, these have a more spiky-looking growth habit, and tend to be more densely packed with their branches and stems.

Formerly known as Stapelia variegata, the Orbea variegata is commonly called the Starfish Plant, or Starfish Flower. These tend to have longer stems compared to the Persian Carpet flower, but blooms are smaller. Flowers are extremely variable, and much like Stapelia grandiflora, these seem popular subjects for selective breeding to favor coloration. A typical flower is a yellow to pale white background with deep red to maroon speckles, with a distinctive raised center circle similar to the next species I’ll list: the Lifesaver Plant.

Many people probably recognize the Lifesaver Plant, or Huernia zebrina. Stems look almost identical to the Orbea variegata, so determining which of the two you have without seeing a flower is almost impossible. Once they do bloom, however, the Lifesaver plant has a glossy ring that’s deep red or pink, with zebra-striped yellow and red petals on the outer edge of the flower.

Less Common but Rewarding Species

The species here are those that are uncommon or downright rare, but rewarding if you find yourself captivated by this group of plants like I am!

Pseudolithos, or dinosaur eggs, are definitely high up there on the “alien looking plants” list. They are extremely challenging to grow for the novice, being highly sensitive to overwatering, and I’ve yet to successfully grow one myself. I’m told they produce truly noxious flowers, guaranteed to keep anyone and everyone you know far, far away from wherever you have them growing. Impressive for a plant whose body rarely gets larger than a few inches across or tall.

The genus Hoodia might sound familiar; some (many?) species are used to make appetite suppressants! They’re also very alien-looking plants that thrive in extreme heat and highly acidic soil. I grow my Hoodia parviflora with a chunk of limestone on the soil, and I’ve heard it recommended to mix a small amount of gypsum into their potting medium to help. Alternatively, using a small amount of vinegar to acidify your water (be sure to test the pH before watering your plants!) can accomplish the same thing. They’re also documented as somewhat short lived; in the wild, plants typically only live about 15 years, although cultivated specimens can live to 20 – 25 years of age.

Hoodia gordonii – Produces huge, pillowy blooms, beginning in late spring and extending through summer. Can reach just over 3 feet tall in ideal conditions. Under ideal conditions, can live up to 25 years in cultivation. One of the easier hoodia to grow. 

Hoodia parviflora – Sometimes called the largest stapeliad, some sources say this can grow to the size of a small tree (up to 6 feet tall)! Less commonly grown as it is more susceptible to rot compared to H. gordonii.

The Caralluma genus also hosts some plants used for appetite suppressants, but their flowers’ smell will do the trick just as neatly. These can vary from very suspiciously stapeliad-like stem appearances that can be a challenge to tell apart from something like a S. gigantea, while others have huge, angled stems that almost resemble a Euphorbia and produce enormous clusters of putrid smelling flowers.

Orbea is the genus of two of the most popular species, but it’s also the genus of some truly hard to find species. Orbea oculata is one that is a challenge to find in the US, but produces clearly distinct and beautiful flowers. Orbea as a genus is nearly as popular for selective breeding and hybridization as Huernia, which also has a large number of species that range in bloom size, color, and pattern.

Thanks to the generosity of the Stapeliad enthusiasts online, the following photos of various Stapeliad species (particularly their blooms) have been shared to display the joy we take in growing these little alien plants.