These are a fairly common little cactus that I’ve had for quite a while, and sold quite a few of. A very attractive little cactus that stay a small, manageable size, they do well as little potted plants. As with most Notocactus species, they produce huge, brilliant flowers in springtime, with blooms so big they can make the body of the plant almost impossible to see underneath. They’re readily available at your local Home Depot (in the US, anyway) and grow readily from seed if you’re able to get your hands on some. It’s not often you see the seeds offered for sale, though, mostly because in the US the plants are produced in mass quantities by enormous wholesale nurseries.
Natural Habitat
Found in Uruguay, they’re not particularly threatened or in much danger. Their ease of growth in cultivation makes the threat of poaching almost non-existent. As with all cactus species, however, human encroachment on their habitat or other human activity may have significant impacts on their standing in the wild.
Hardiness
Well-equipped to handle hot summers, especially when given plenty of water, these are also surprisingly tolerant of cold winters. If kept dry, I’ve had both my personal plants and those I’ve had as inventory for sale do just fine with temperatures in the high 20s F at night.
They will, however, be happier if you’re able to keep them warmer at night (about 40F) – but not too much warmer, or they won’t experience the winter dormancy they seem to need for a good bloom season.
They cannot take a hard frost, and need daytime temperatures in the 50s or 60s at least.
April 2021, when I first potted up my normal cactus and put it in the greenhouse.
Potting your Notocactus schlosseri
As a small species, even when mature, you’ll likely find them for sale only in 2″/2.5″ pots. If you happen to see one in a larger 4″ pot, it’s an older/more established plant – and unlikely to get much bigger!
The small adult size makes them excellent candidates for mixed pots, especially when combined with their forgiving nature and how much they appreciate regular watering in summer months. Unlike many of the other cactus species I grow, once it’s about 80 – 85F during the day, they appreciate consistent water as soon as their soil dries.
And when it comes to soil, they aren’t terribly fussy. I find them to have finer roots than some other cactus species, and appreciate a little more compost in their soil than others.
I’ll include some affiliate links below if you need to order your materials online; they help pay for my server costs and I appreciate every click!
My preferred mix for these:
- 50% cactus/succulent soil
- 25% pumice
- 25% orchid bark (smaller chips, if you can get them)
Keep in mind that I grow mine in a toasty hot greenhouse, so I need more moisture in my mix for these than you might. If you’re in a more humid area, or if you’re growing them indoors where it doesn’t get above 78 during the day, increase your pumice/orchid bark ratio (swap the cactus and pumice ratios is my suggestion). The roots can be very prone to rot if they stay moist for too long, and you’ll need to balance that.
My Notocactus schlosseri monstrose when I potted it up in November 2021 – a random discovery in a flat of wholesale plants. When growing enough plants in volume from seed, mosntrose (and variegated) forms pop up. Large scale wholesaler staff rarely have the time or inclination to pull out the “freaks” like these, and so you may discover them yourself in big box stores from time to time!
(If you can beat the employees at the store to them, that is)
Same plant about a year later, November/December 2022
Watering your Notocactus schlosseri
As I’ve alluded to through this post, in summer, these are thirstier plants – with the caveat of being exposed to adequate light, which I’ll address next.
For good blooms, they appreciate a bit of balanced fertilizer at half strength. My all-time favorite is this stuff from Jack’s, just at half strength. I offer it once or twice in spring, when the weather is first warming up, then with every watering for summertime. By September, I’ve usually stopped fertilizing completely.
Again, it’s important to remember my greenhouse conditions as opposed to your house or patio conditions. In summer, I am often watering these every week, as the greenhouse routinely sits at 120F+ every day. They would likely appreciate even more water than that; last year, they looked pretty rough mid-summer. I think this year (2024) I may move them under my benches to help keep them cooler and even more shaded so they need less water.
My inventory plants, kept outdoors in partial shade, also were watered every week but were more plump, showed growth, and generally looked better than my sad little greenhouse specimens. Average summer temperatures from about June to September are with 80F+ every day, and nights rarely below 60F. July and August usually see highs in the 90s or even 100s, and as long as these had some shade and water in the evenings, they were fine.
If you’re growing yours indoors on a windowsill and you’ve got the air conditioning going, or it’s not hotter than 80F where you are, then you won’t need to water your Notocactus schlosseri nearly as often! I’d err on the side of much less, in fact – maybe once a month.
When you water the cactus, it should flow completely through the pot and drain out of the bottom. If it’s indoors, try not to immediately put it back in a saucer to sit in the water and get soggy ‘feet’. Outdoors, it’ll just keep draining as it needs to!
The water draining out and not sitting at the bottom of the pot is critical for flushing out any deposits or minerals from your tap water, and preventing the roots from rotting. The soil should be dry, or nearly dry, within 3 to 5 days at most after you’ve watered the cactus. If it’s still damp a week or more later, it’s not draining well enough (meaning you need more grit or pumice added to your mix) and you should re-pot it.
Normal Notocactus schlosseri blooming in May, 2023
Light for your Notocactus schlosseri
As a smaller species, these are not cacti that need full blazing sunshine all day, every day. In fact, they look their best with some protection.
In my greenhouse, mine are shaded with 40% shade cloth almost year-round, as the greenhouse sits in full sun. I’ve experimented with different placements within the greenhouse that get more morning sunshine (coming in from the east, sideways) or more afternoon sun (coming in from the west, sideways) and found the direct morning sun to maintain the best color and spine development.
For your own plant, I strongly suggest finding something similar. If growing indoors on a windowsill, you will likely need to consider the brightest, most south-facing window you have to get maximum light. While these do well in partial shade outdoors, indoors you will always have part of the sky and light blocked due to the nature of being, well, indoors. In summer, you may want to simply place the cactus outside on a patio that gets morning sun.
You can tell if your Notocactus is receiving enough light if the center remains concave, like someone pushed the center of it down a bit. Depending on the growth and light exposure, it can be quite a deep-looking dent (in the bloom pictured above this section, it almost looks like the cactus could be folded together like an envelope).
I’ve noticed as mine get more water and begin growing for the year, the dent does get less pronounced, but it’s almost always there.
If your cactus is flat on top, with no center dent, it’s not getting enough sunshine and needs more ASAP. I’ve never seen one etoliate to the point of having the central growth bulge up and out, but if that’s happening, the cactus is likely so light-starved it’s close to dying.
Blooms emerge from the center, and bright light is needed to encourage them to open. Mine have still bloomed even with cloudy days, but they produce more flowers more often with adequate light.
The normal Notocactus shlosseri in April 2024. You can see the slight indent at the top and slight spiral of the ribs as it’s grown – that’s from not moving in the greenhouse and the center growth point following the sun over time.
Same plant as above, April 2024, but seen from above.
Above, you can see my older plant that has a decent height to it – and in the center, it’s got the dent. Another cool thing that happens if you’re able to keep the cactus in one spot year after year (as I’m able to with the greenhouse) is that as it grows, that growth point in the very middle of the top of the cactus strives to follow the sun. As a result, it slowly grows in a subtle spiral – not quite a corkscrew like some Cereus species will, but a subtle spiral nonetheless.
Flower buds will develop at the edges of that dent, and when they open they look like a glowing crown. If pollinated successfully, the fruit (which you can see hanging off the sides of my plant) will ripen in about a month or two. You’ll know the seeds are ready to be collected when the fruits seem to almost deflate, and you can gently tug them off with tweezers. Have paper or a little receptacle ready underneath to catch the seeds! They’ll come tumbling out of the base if the fruits are as deflated as mine look in these photos.
Do you have a Notocactus schlosseri at home?
These are so common here in San Diego that I imagine them to be common elsewhere, but that’s not always the case.
Do you have one of these of your own?
Share a photo with me on Instagram, and let me know how you’re growing yours! You can find me @Trexplants.
Happy growing!
At right – Notocactus schlosseri, monstrose April 2024
This plant has never bloomed for me, but with the little heads emerging to one side, I’m hopeful I’ll get some flowers this year.
