This cute little cactus is one of the first Gymnocalycium species I ever took home – excluding the ubiquitous Moon Cactus, of course. It was my first foray into less common cactus species, and I was enamored with the deep red-pink color of the body.
Little did I know, at the time, that the color was the cactus equivalent of screaming stressfully about existence but hey, live and learn.
I still have that first cactus, and while it’s significantly less pink, I’m still very much enamored with the species.
At left is the little specimen I first purchased back in 2018! Originally a greenish hue with dark purple shading under the tubercules, it quickly became entirely purple in its placement in the hot sun on our retaining wall.
Even stressed and slightly puckered from lack of water, it bloomed all through spring and summer, which is a consistent trait in all of this species that I grow.
At the time I had purchased this plant, it was labeled simply “Gymnocalycium rotundum”, which I now know is not even the correct variety of the species.
These are noted as Gymnocalycium anisitsii in Graham Charles’ book, “Gymnocalycium in Habitat and in Culture”, and are also noted to be such on Llifle. I have seen them listed for sale primarily as Gymnocalycium damsii, at least locally, and I doubt your local club or show will ding you for using that species name rather than anisitsii.
Distribution and History
The type subspecies is limited in distribution to the valley of the River Paraguay, with recent reports (at least, as of 2003) noting that the habitat extends into Brazil on the north side of the River Apa. The most northern limit is at Porto Murtinho, but at that point the distinction between Gymnocalycium anisitsii, the type locality, and its subspecies damsii is unclear.
The ‘true’ anisitsii seem to have white flowers with very pale pink as compared to the distinctly pink and fuschia colored blooms of most plants seen in cultivation, which is indicative of the difference in subspecies.
Gymnocalycium anisitsii ssp damsii was first described back in 1898, originally classified as an Echinocactus!
The book I’m referencing for much of this history and distribution (“Gymnocalycium in Habitat and Culture”) notes that it is particularly challenging to decide how to treat the subspecies Gymnocalycium anisitsii ssp damsii – the species itself being incredibly variable, and those who have visited the region and photographed/collected type plants have not necessarily done a great job of documenting the plants.
I am no taxonomist, and include these details as context for those who find plants that are similar…but not quite…and they’re questioning if their labels are accurate.
That said, the species Gymnocalycium anisitsii is variable, ranges along rivers, and is found in Bolivia, Brazil, and Paraguay. Flowers can be white to deep pink, and selective breeding have assuredly created plants with more intense flowers than those found in habitat. In habitat, they are often found under low bushes, protected from extreme sun and happily pupping profusely. They can form large groups or colonies, and vary immensely from population to population.
Gymnocalycium anisitii ssp. damsii is actually quite easy to grow, like much of the Gymnocalycium genus.
It is very demonstrative of its stress levels, as I have learned first hand, turning a darker and darker shade of purple the more stressed it gets. The trick is to balance the beautiful stress color with a healthy, happily growing plant. As pretty as my neon-pink cactus was, once I learned more about cactus cultivation in general and gave it better growing conditions, it’s never been that shade again.
Even when stressed and on the verge of dying, these cacti will bloom, so don’t take the sight of flowers as a sign that your care is on par. Look to the cactus body itself for your signals!
Soil and Pot Size
As with all cacti, care for Gymnocalycium anisitsii ssp. damsii begins with what you pot it in.
I have grown several with great success in simple 5″ plastic pots, which works well for single, smaller cacti. They will create surprisingly large root systems, given the space, but should not be too dramatically over-potted (such as potting into an 8″ azalea pot, or a large dish pot, for example).
My own cacti exhibited the most stress when under-potted, and seem to appreciate at least 5″ of pot space with suitably gritty soil.
When it comes to mixing the soil, my favorite blend of at least 50% pumice and 50% cactus soil works beautifully. Again referencing my sad, stressed cactus, its soil rapidly became compacted and held little moisture in its terra cotta pot. Ironically, not mixing more pumice into the soil made it compact faster, so within a year, the soil was rarely saturated after watering, even if I’d doused the plant enough that it should seem well watered.
I’ve repotted my oldest cactus of this species about every 2 years, and have seen it respond well as a result. My newer specimens are due! Plan to repot your own Gymnocalycium anisitsii about every 2 years as well, although stretching it a bit longer can be acceptable if they are in a porous mix and are fertilized.
I particularly enjoy seeing these cacti change with the seasons. Well-grown G. anisitsii ssp. damsii seem to green up and darken with the seasons for me.
With the shorter days and increased cloud cover of winter, they tend to green up, especially if it’s a mild and warm winter and I have to water them (seen at left). In summer, with long days, high temperatures, and lots of sun, they darken to a deep maroon, almost purple shade. With less water during these periods of stress, the color deepens and they start to prune and wrinkle.
If kept dry in winter, they can tolerate surprisingly low temperatures – mine routinely shrug off nighttime lows in the 30s and high 20s.
Watering your Gymnocalycium anisitsii
While extremely forgiving in cultivation, there are some considerations to keep in mind when it comes to watering your cactus.
When coming out of winter dormancy, water sparingly to prevent unsightly splits and cracks. This doesn’t mean spritzing with a water bottle – I mean use a glass of water, or your watering can, and splash the plant at first. You don’t want the water to run out of the bottom of the pot, but you do want the soil to get enough water for the roots to drink some up. Using a spray bottle to mist the soil doesn’t offer enough water to be impactful.
As with all of my greenhouse-grown cacti, I use a balanced 1:1:1 fertilizer at half strength to fertilize these. In summer, I strive to fertilize every time I water, as I lean to a higher inorganic mix of soil. When you have less organic material in your potting mix, you need to offer nutrients to the plants another way – and a dilute, balanced fertilizer does the trick.
In spring, I fertilize every 2 or 3 waterings, as I’m taking my time waking my plants up. This year (2023) has been extremely cloudy and rainy, so while my greenhouse plants are sheltered from the rain, they’re not getting the sunshine and warmth I’ve seen in previous years. As a result, my plants in the greenhouse aren’t getting fertilizer – there’s no need if they’re not getting the heat and sunlight that they’d need to process the extra nutrients.
As I noted early on, exposing these to full sun can result in some really gorgeous stress coloration…but your cactus won’t grow. In fact, you may stress it so severely that the lack of growth results in rot or dessication to the point of no return.
Instead, aim for morning and/or evening full sun exposure, and shade the cactus during the hottest and brightest part of the day. Mine look their best, with darkly contrasted tubercules, consistent growth, and blooms, when I keep them in the greenhouse at full sun but with a 40% shade cloth protecting them.
You don’t need to math out a shade cloth to grow these yourself, though. Just keep them somewhere that is shaded at noon, and you should be just fine.
Grow Your Own!
These are delightful, easy to grow cacti that are extremely forgiving of nearly all beginner mistakes. I have grown several from seed, propagated pups, and have enjoyed the mature plants in my collection for years.
Their profilic blooms, ease of cultivation, and very attractive stem growth makes them solid keepers for my cactus bench. Keep an eye on my shop for seeds and seedlings from my plants to be available!