While there’s other species that will blush or turn purpley to maroon shades, these three are the species that will turn the most brilliant purple and tend to be readily available.
Purple Opuntia Species
Before we dive into care, let’s talk about the three species that will be the most purple AND the easiest to grow and acquire.
How am I defining a “Purple Opuntia”?
Like the plant pictured at right: new paddles that emerge in full sun should be a pretty bright, very obvious purple color.
In full sun and under some water stress, the mature paddles should also turn purple.
It’s also definitely an Opuntia: it has paddles, glochids, and long, extremely stabby spines. Compared to other cactus species, the long spines from these seem to have barbs at the tip, and get really wedged into your skin or clothing if they latch on.
Opuntia santa-rita AKA the Santa Rita Prickly Pear
This is probably the most common species that gets people excited about “purple prickly pear”, and would be the species I’d expect someone to be looking for if they use that common name.
Found natively in the US in Arizona, New Mexico, and Texas, they grow to the size of a moderate shrub, and old specimens can form a short trunk. Extremely large or old plants may reach up to 6′ tall, but more often it’s far less.
Notably, they have large, flattened paddles with reddish glochids and long, orange to black spines that emerge.
The most obvious distinguishing feature if you’re uncertain of species is that the Santa Rita produces brilliant yellow flowers. The center is yellow, the stamens are yellow, the whole flower is yellow with tissue-papery petals. Very pretty and extremely striking against the purple body of the plant.
Opuntia basilaris hybrid – “Baby Rita”
This is a hybrid from Waterwise Botanicals, a San Diego nursery less than an hour north of me!
Not a true species, but easy to identify: it’ll be the same deep purple as the Opuntia santa-rita, but the paddles are thick, squat, and significantly smaller. The parent plant of this cross is called a “beavertail opuntia” because the paddles supposedly resemble a beavertail, but these are too thick and pudgy to be confused for such a thing!
I find this hybrid to grow faster and clump more quickly than either of its parents, and it puts on QUITE a show when it blooms.
Where the Opuntia santa-rita will produce brilliant yellow flowers from April to June, the Opuntia “Baby Rita” produces brilliant pink flowers!
Opuntia macrocentra
This is also very commonly referred to as the “Purple Prickly Pear”, which is just plain confusing given that the Santa Rita is also often called a purple prickly pear.
I won’t say one or the other is the “correct” common name, but I will point out this is precisely why Latin names exist.
Opuntia macrocentra is much less common than the Santa Rita, and they can be nearly impossible to tell apart if the Santa Rita is kept in a particularly bright exposure or stressed state. The macrocentra is often noted as having distinct black spines, which are extra striking against the purple and blue base, but if you look up photos of Santa Ritas in habitat, they can also have spines dark enough to be confusing.
Having grown all three, in my experience, this is the slowest growing of the species. It will still reach 6 feet or so in height (if planted in-ground), but takes quite a while to get there. It’s also more cold-hardy than its cousins.
When in doubt if you have a macrocentra or a santa-rita, the flowers will be your dead giveaway: Opuntia macrocentra has yellow flowers but with a brilliant red center that’s impossible to miss.
Just to be extra clear and obvious, let’s look at them all side by side (assuming you’re on a computer, not your phone). At worst, on a small screen, these will all show in one column.
While macrocentra has those huge, incredible spines, in a more shaded exposure they won’t grow as prominently, while santa-rita will absolutely start making ginormous spines in brighter light. The best and most concrete confirmation of species will be flowers.
Even with small images or at a distance, the flower colors should be distinct enough to tell the difference!
Opuntia santa-rita
Opuntia “Baby Rita”
Opuntia macrocentra
How to Grow a Purple Prickly Pear
All three types have nearly the same care requirements, so that part is easy at least!
It’s worth noting that all three are either species with ranges that include a portion of the American Southwest, or is a hybrid of American Southwest species. They are all pretty cold-hardy for cacti, and forgiving of much of our weather. At worst, they’ll need to be potted and come indoors in winter for the areas that get a hard freeze and weeks of below-freezing weather.
Soil for your Purple Prickly Pear
Opuntia are some of the most resilient cacti on the planet, and will probably survive no matter what you pot them in. I’ve left some cuttings sitting on a brick wall for months at a time, and they still made new pads and even bloomed!
That said, if you want yours to thrive and not merely carry on despite the suffering, you’ll need a nice soil mix that drains well and doesn’t turn into a dried soil-cake.
Compared to other cacti, these are much more forgiving of simply using straight cactus and succulent soil – but I do still like to mix in 25 – 50% pumice if I’m keeping them potted. In pots, the pumice adds extra drainage that encourages healthy root growth and prevents the soil from the two extremes: getting so dry it turns into a brick, or being so wet it turns into a swamp at the bottom.
If you’re planting your Opuntia in the ground, you’ll want to look for a spot that’s very well draining or simply bakes and dries out within a day or two.
My Opuntia that are in-ground are all in dense, sandy, clay-ish soil that’s extremely hard to saturate, dries fast, and I have to dig a large area around any plant I add to the ground to ensure there’s adequate drainage as it gets established. My soil is garbage, but it’s hot garbage, and they love it.
I will point out that I do dig a very large hole for any plant going into the ground: usually half again as deep as the pot the cactus came out of, and twice as wide as the cactus’ original pot. I’ll pour in the excess soil from the pot, and usually I break up the root ball over the hole as well. If it’s particularly packed soil, I might even add some mulch in the hole and then around the cactus to help with moisture retention, decomposition, and overall soil health.
The big thing is that there’s room for drainage, room for the roots to expand into, and I plan for how crummy my dirt is.
If you have particularly rich soil that works well for growing vegetables and a leafy garden (you lucky SOB), that’s probably going to be too rich for an Opuntia. Consider a raised planter where you plant it in 50/50 pumice and soil, or 50% soil, 25% pumice, 25% mulch or orchid bark (if you can get that in bulk in your area). Remember that these are cacti evolved to thrive in harsh, dry, rocky soils, and if it’s too wet for too long, they’ll simply rot.
Or, if they don’t rot, they’ll be too happy and you won’t get that purple color they’re so well known for.
Watering your Opuntia
These need far less water than you think, but as the years go on with your plant in the same pot, the need goes up much faster than you expect.
What do I mean by that?
The Opuntia macrocentra at right did great with the same watering schedule as the rest of my greenhouse for about 3 years – but this year, 2024, it is big time on the struggle bus. The central stems are getting bark, the new pads aren’t as strongly spined, and any new pads that come in are very thin and the overall look of the plant is decidedly “crispy”.
It’s been 4 years since I potted it up, and it’s very obvious that the plant needs a soil refresh.
If I don’t intend to repot it, I need to water it more often (and fertilize) to get it to produce the type of beautiful, showy growth seen in the photo at right.
Opuntia macrocentra in July 2021
So for potted plants – the longer your cactus has been in the same pot, the more water it will need in hot summer months. Saturate the soil, and use a chopstick or just stick from outside to poke the dirt and check that it’s genuinely getting saturated all the way through. For mine in this pot, the first couple years it was easy to saturate fully and see water draining out the bottom.
In the last two years, though, the soil has noticeably pulled back from the edges and has sunken in, both signs of “soil compaction” and that the soil has lost volume. This is also an indication of poorer soil quality, and to get blooms or new pad growth, fertilizer is a must.
The photo above is my macrocentra as of June of 2024, showing new paddle growth (and the low quantity of large spines that results from being under 40% shade cloth!).
I have this in the “watering” section, rather than the sun or soil section, because in order to get new growth and maintain this cactus in old soil I’ve had to baby it considerably.
SO:
Freshly potted? Are you using pure cactus soil with no amendments? Water it less than you think: once a week at most in peak summer months, more like once a month if you’re in a particularly humid climate or the cactus is indoors.
Has it been in the same pot for years? When you water it and then use a stick to poke an inch or two down, is the soil down there dry, or does it immediately sponge up the water? If dry, water it more often – that’s when every week will probably be appreciated. If it’s still turning into equally moist soil after 3 or 4 years, tell me what potting soil you’re using, because that’s miraculous.
With amended soil that has more pumice or bark to encourage drainage, you can lean into more frequent watering in summer months. Unless you’re living in the high deserts of Arizona, Nevada, or New Mexico, that means once a week at most. If you get regular summer thunderstorms, you may be able to skip watering your opuntia entirely if you keep it outdoors.
Those who can plant them in-ground can play this much more by ear. The only time to really make sure you’re watering consistently is in spring, when the new paddles are produced. This keeps the new growth consistent and attractive, and minimizes the sort of scarring and reticulated pattern that pops up when they get less water than they need as they plump up new paddles.
In winter, keep your potted Opuntia pretty dry, but the moment the risk of frost has past – start watering again.
Opuntia macrocentra, April 2021, chickens for scale
Note the new paddles coming in!
Fertilizing your Opuntia
Right around when you should start watering your Opuntia in late winter is when they also benefit from the first hit of fertilizer.
You see, Opuntia only produce new paddles and flowers one time a year: in spring. For where they grow in the American Southwest, our most intense rainy season is usually late winter through spring, so they bank on that to produce their new growth each year. They still store up energy and are actively growing the rest of the year, but if you want blooms – feed them right before they start making new growth!
A basic balanced fertilizer at half strength is all you need. My beloved blue powder fertilizer works wonders and is extremely easy to use, so I highly recommend it.
Stop feeding them around the time the newest paddles have fully grown in and hardened off. If you fertilize a couple times more beyond that, they won’t mind, but they don’t really need it.
One of my long-suffering Opuntia santa-rita planted by the edge of our driveway, getting roasted by the sun and baking hot – and loving it.
Light for your Opuntia
These bad boys need full sun, full stop. If you want a purple cactus, it needs insanely bright light. They can grow fine with shade (see my Opuntia macrocentra pictured earlier), but for the best spine development, flower growth, and overall appearance, they should be in full sun.
This means outside, fully exposed, from nearly sunup to nearly sundown. A south-facing patio *might* be close enough, but I can’t emphasize enough how much these thrive in the sort of sun exposure that strips paint off cars.
Can you grow these indoors?
Sure, maybe. If you have a south-facing window, giant windows, and the room they’re in also gets hot enough to make your air conditioning cry.
If you want them to be purple like their namesake, you’ll need to plan on a way to move them out into full sun. They also need to be hot! You can grow them indoors, and I’ve had friends do so, but they go from thriving to dying slowly. You won’t see new pads develop, and if they are actively growing, the pads will turn greener and greener as time goes on.
For best spines, best color, best growth – toss these bad boys outside as soon as the risk of a hard frost has past. Ensure they’re dry (if nights are below 40F), but they should be outdoors in the harshest of exposures as much as possible if you want them to look their best.
Propagating your Opuntia
These are so easy to propagate, it’s no wonder that’s the primary way they’re grown. Opuntia hybridize enthusiastically with any relatives in the area, so growing them from seed can be a bit of a crapshoot.
Fortunately, you can guarantee extact species and clones by just growing them from paddles.
The best time of year to propagate your Opuntia is late spring to mid summer, when days are hot and nights are rarely below 60F. The warmer the weather and the longer the daylight hours, the more readily these will root from a cutting.
Cut paddles or branches where they have a “seam” – if you’re using thick leather gloves, you should be able to wiggle off a paddle or branch without even having to cut the cactus. Aim for established paddles, as in, they’re not newly grown this year.
A big branch of Opuntia “Baby Rita” from a friend
I prefer to root mine in pure pumice, but you could plop the paddles directly into soil if you want to. I like pure pumice as it is dry enough to keep the paddle from rotting, but will take water and hold onto it just enough to keep the paddle from completely dessicating.
I’ll set mine up in pure pumice in a half-filled pot, and then leave them be in the greenhouse for a few weeks. Most of the water they get is splash or overflow from me watering the cacti on the benches (I keep the pots under the benches on the ground), but at least once I’ll water them directly to ensure they don’t dry out. Keep in mind that my greenhouse is usually 100F+ each day, so it’s hot. If you’re not experiencing such high temperatures, a little splash of water every couple of weeks is probably plenty.
After a few weeks, I’ll use tweezers or tongs to gently wiggle the paddle. A great sign is when it feels like there’s resistance – that’s a sign there’s roots growing, and to keep doing what I’m doing. I’ll usually give them another week or two at that point to ensure the baby roots are really establishing.
From there, I’ll either add a layer of cactus soil on top of my pumice, then add another layer of pumice (the soil will wash down into the initial pumice layer and ‘feed’ the growing young cactus), or just pull out the whole baby rooted plant and repot it with a full cactus soil mix.
You don’t need to add rooting hormone, and you don’t need to baby the cutting. Time of year is crucial, as is temperature and light. It needs to be hot, it needs to be long daylight hours, and they need to be bright. If it’s not spring or summer when you’re trying to root the paddle, it may take months before it produces roots – and surprise surprise, I’ll bet you it’s summer when they finally pop out.
Above is a big batch of propagated cacti I just set up last week – this is also the time of year to propagate your Myrtillocactus, if you’re so inclined.
I have my first spring props from my Opuntia macrocentra rooted and ready to go (June 2024), and if I still have any available they’ll be listed for sale in the Shop section of my website. This year I have also propagated my Miqueliopuntia miquelii as well as multiple paddles of my Santa Rita and Baby Rita. As plants become rooted and clearly established, I’ll list them in the shop section.
Thank you, as ever, for reading my post – and I hope you found this helpful! If you have questions that this post didn’t answer, don’t hesitate to email me at [email protected]. I’m always happy to help.
