Despite being an incredibly common species in cultivation, especially here in the US, I can’t find much online about where they grow in habitat. They’re a Mexican species, with Llifle describing them as coming from a more southern part of the country rather than the deserts bordering the US.
The area they’re from, according to Llifle, is Michoacán – a temperate region with summer rains and a dry winter, but annual precipitation that’s similar to slightly higher than what we receive here in San Diego. Average temperatures trend a little lower than the rest of Mexico, averaging only in the high 70s to maybe low 80s. Weather stations in the area do show record highs in the 90s, though, so overall: very moderate weather that can occasionally get a heat wave, like just about any temperate northern climate.
No wonder these are such popular cacti sold in nurseries – they thrive in the same conditions we do!
August, 2021
Appearance
Before we dive into cultivation guidance, there’s a fun element to point out about their growth that can sometimes trip up growers who haven’t seen these as older plants before.
Mammillaria matudae doesn’t stay squat and short and cute. It is a columnar cactus, meaning it develops into tall columns, rather than staying squat. It also tends to offset at the base, producing new arms that sprawl rather than grow upright. Mine has yet to produce new arms, but this year it’s officially given up on pointing up instead of sideways, so they must be coming soon.
I mention this to say: if your ‘thumb’ cactus is getting some length to it and starting to lean, that’s normal! They’re supposed to look like that.
Same cactus, April of 2024! Now in a 6″ pot.
Pots and Soil for your Mammillaria matudae
A nice thing about these cacti is that they have a relatively small root ball, so they don’t need an overly large pot. I grew mine in a 4″pot for 3 years before repotting it this spring.
When you get them as smaller starts, they can benefit from being repotted every year so they’re growing in fresh soil, but I’ll admit I didn’t do that at all. This Mammillaria along with a couple others I simply repotted from the nursery and left in those pots for several years.
I tout a well-draining soil mix most of the time, but these are extremely forgiving. If possible, look for a mix that has pumice in it already, but your standard “cactus potting soil” should work fine with little to no doctoring.
Choose a pot that’s at most 2″ larger than the one you purchased it in. Pots tend to come in pretty standard sizes, so if you find the cactus in a small 2.5″ pot, upgrade to a 4″, etc, etc. If potting into a decorative pot, you’ll likely need to measure it or at least eyeball it to make sure it’s not oversized. The photo of my little Mammillaria matudae at the start of this post shows why you should also measure based on root ball size, not plant size – the cactus in that pot had a 2.5″ root ball, and when moved up to the 4″ round pot, there was at most about an inch of space between the root ball and the sides of the pot. That’s ideal! You can go a little larger if you’d like, but they don’t necessarily need it, and having a very oversized pot can cause complications:
- Rot in pockets of the soil that take longer to dry
- Pockets of soil that dry faster, or don’t absorb water at all, leading to uneven root development
- Cactus focuses on expanding roots rather than growing above ground, making it take longer to gain in size – or “eating” too much with lots of rich soil, causing stretching when the body does grow
May 2021
Top Dressing
In many of my photos, you might notice a layer of pumice on top of the soil. I like it as a top dressing for cacti that I’m actively trying to grow to increased size: it ‘breathes’ well (air exchange for the roots), but also helps the top layer of soil from evaporating faster than the rest does.
You can also use:
- Lava rock pebbles (similar to pumice, more fun colors)
- Akadama (a type of Japanese clay)
- Coarse grit in your preferred color
Try to avoid using black colored top dressing, especially if the cactus is outside, as the black stones often get quite hot very quickly and can burn your cactus.
I also recommend avoiding unsifted decomposed granite – the fines will turn into a caked layer on top of the soil, making it hard to water. You should steer clear of sand for the same reason: it’ll cake up or simply wash through entirely.
Aquarium gravel works fine, but it’s just not my favorite. Whatever you use, just make sure the water is able to freely flow through it and doesn’t puddle on top, or just wash the top dressing right into the soil.
November 2022
Watering your Mammillaria matudae
I can’t emphasize enough how forgiving these are compared to other cactus species. Outdoors in summer months, it’s nearly impossible to mess up watering them as long as you’re not doing it daily, or less than once a month.
If the soil is dry, the weather is over 75F, and it’s sunny out, you can probably water it. Water it in the morning, afternoon, evening, whenever you like. It won’t care. Try not to douse it midday, just to avoid cooking it, but that’s about it.
Indoors, you have to be a little more circumspect. Without outdoor swings to high temperatures or nighttime drops, the growth won’t be as robust or pronounced. If you’ve got it in a south-facing window and the area its in gets noticeably warm, that’s different than if you’re having to use a grow light to supplement around cloudy weather or a window that’s not as bright!
Basically: these cacti should be watered when they’re growing, which is when it’s hot and bright out. In winter, they can go weeks or even months without any water at all.
In my greenhouse, I stop watering just about all of my cacti sometime in November. They’ll get a splash of water once or twice when we get a week or two of sunshine, but they stay pretty dry. If nights are below 40F, the cacti are pretty much dormant, and too much water will cause them to rot.
So indoors, where the weather isn’t as hot or as cold, your approach will need to be more moderate.
Potted up, September 2023
Fertilizer for Mammillaria matudae
If you’re repotting your cactus every year, you don’t need to offer fertilizer on top of that. The fresh cactus soil will feed it for you!
If it’s in the same pot for more than a year, though, some fertilizer in summer months will be appreciated. As with all of my cacti now, I just use a balanced fertilizer at half strength. I feed my cacti pretty consistently in late spring and through to about mid-summer, and then taper off as the weather gets really hot.
Using fertilizer, or repotting your cactus, is the best way to ensure it blooms for you during the growing season! The little crown of flowers will show up in spring, and you’ll see more appearing almost all summer. The more consistently fed the cactus is, the more likely you are to see continuous blooming.
Light and Sunshine
For the best growth, these need extremely bright light – preferably full sun, but light shade works if you’re in a very hot climate (Arizona, I’m looking at you). Mine is in my greenhouse, with 40% shade cloth.
Due to how quickly they grow, these cacti will demonstrate their growing conditions like tree rings. If you look closely at mine at the right, you’ll rings of darker spines and paler spines.
I think the darker vs lighter spines on mine are from one of two things:
Where the flowers come out ends up darker, though I’m not sure why.
OR
The sun hits the greenhouse differently in winter vs. summer, and the late winter/spring exposure is more direct sun than summer months (which is why I put up shade cloth on the wall in winter!).
April, 2024 – after watering
Mine is also grown in a touch too much shade; it’s not etiolating but it should have denser and longer spines, especially near the apical growth point.
Now that it’s reached a size where even with water, it simply lays flat, I may move it to an outdoor placement year round. However, since we’re in the middle of San Diego summer, this isn’t an ideal time to move a sheltered plant outdoors. The heat and sunshine will very quickly scorch it if I’m not careful. A more ideal time is in late winter, after the last chance of frost has passed. The days are shorter, and temperatures mild, so the cactus has time to slowly adjust to the increased amount of sunshine and heat that summer will bring.
Now, considering any cacti grown indoors, you’ll likely need supplemental lighting. Without adequate light, this species will simply grow more slowly, or not at all. Rotating the plant in a window will only work for so long, as they do eventually lean over and start to splay out flat.
Ideally, this is a cactus that should be grown outdoors, in nearly full sun, and only brought under shelter in winter to protect it from snow or a hard frost. Under a patio cover or on a table in the shade is not the same as full sun!
Above is my Mammillaria matudae as of this month, July 2024! Plopped over, still getting longer, but no sign of pups at the base yet.
The body of the cactus is now heavy enough that it tips over the pot, so I’ve had it laying over the extra space on one of my Copiapoa grow-out pots.
And that’s it!
This is a fun, goofy species of cactus to grow that is more rewarding the larger and older it gets (in my opinion, anyway).
The cute little crown of flowers appears most prominently in spring, but can be encouraged to keep appearing in round after round through the summer months. If you spot one at the store – give it a shot!
