How To Care for & Propagate Rock Purslane Succulents
(a.k.a. Cistanthe grandiflora or Calandrinia spectabilis)
There are lots of succulents out there I could call “super succulents” meaning they’re beautiful, interesting, and easy to grow. Succulents are so popular now, and I think a big chunk of why is that many of them check these boxes making them rewarding for even a novice plant parent or beginning gardener.
Rock purslane, a.k.a. Cistanthe grandiflora (or Calandrinia spectabilis which is the old name before the botany gods reassigned it to Cistanthe) really has become a favorite though with it’s beautiful fuchsia flowers and months long bloom time, cold hardiness, and attractive blue-green succulent foliage.
Rock purslane growing conditions
Rock purslane foliage & growth habit
Propagating Rock Purslane
Succulent propagation soil mixes
Cistanthe grandiflora propagation video
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Rock purslane growing conditions
Flowering
I don’t know of another succulent that blooms as long as this one does. In Northern California, it produces fuchsia pink-purple blooms continuously from about April through much of fall, and in warm, frost-free areas like Southern California, it blooms nearly year-round. It’s 1” to1.5” single rose-like flowers develop from a 12” - 24” repeat-blooming inflorescence - no deadheading required! (Please don’t dead-head - you’ll lose all your flowers).
The flowers are tightly closed in the morning, open during the day, and close again in the late afternoon. They also close up in windy conditions. Rinse and repeat for months.
Rock Purslane at 7:15 AM - the flowers haven’t opened up for the day. (Click to enlarge)
Cistanthe grandiflora at 12:00 PM. Flowers are open unless its a windy day. (Click to enlarge)
Rock Purslane at 7:00 PM - flowers have closed up for the night. (Click to enlarge)
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Rock purslane frost tolerance
On top of the almost non-stop blooms is it’s tolerance to cold. I’ve seen varying temperatures, but it’s hardy down to around 15 Fahrenheit. Here in the Bay Area of Northern California, we definitely get frost on several occasions during winter and I’ve never seen it damaged. It is often listed as hardy to USDA Zone 8 (10-20° F) and reportedly can suffer frost damage at about 18 degrees F.
Rock purslane drought tolerance
Cistanthe grandiflora is a succulent, so no surprise then that it’s drought tolerant. Mine grew like gangbusters in the hottest spot in my garden - next to a south-facing stucco wall with no irrigation (and trust me, I didn’t water it either).
Now that my landscaping was just redone, it does have a couple emitters going to it (I think) which I’m sure it appreciates, but it will survive just fine with minimal to no irrigation once established, blooming all the way. Wikipedia describes the genus Cistanthe as being adapted to climates that almost completely lack rainfall.
Light
Grow your Cistanthe grandiflora (Rock Purslane) in full sun to part shade. I’ve grown mine in full south facing sun and in another spot that gets a some shade. It seems happy in both and I kind of think it prefers a little shade. The foliage can turn reddish with sunburn if it’s blasted with too much sun and heat (picture south facing full sun with concrete).
Rock Purslane is cold hardy to about 15 degrees F and can survive on little to no supplemental water. Plus it blooms for months at a time attracting bumblebees. (I love watching them bumble about bumping into flowers :) Photo | Greenhouse Studio
Rock purslane foliage & growth habit
Cistanthe grandiflora’s leaves are a succulent, blue-greenish color, attractive and tidy when not in bloom but it can develop neck-like stems where old leaves die off. Annies Annuals recommends just cutting them back in winter and adding a little compost if you want them to be fuller next spring. It can fairly quickly spread to a 10’x5’ succulent mat ground cover, doing a good job of suppressing weeds along the way. I get almost no weeds where it’s growing.
My Cistanthe just kept creeping out from the planting bed until it occupied 3’ of concrete in addition to the bed until it was cut down to size during the re-landscaping. I’ve never seen another plant do that, much less a succulent, and yet it’s not aggressive or invasive at all.
Rock Purslane’s succulent blue-green foliage grows in clumps and inflorescences grow from a terminal point. Cistanthe is very drought and heat tolerant and can survive with no supplemental irrigation. It’s also more frost tolerant than many succulents down to about 15 degrees F and can be grown in zones as chilly as USDA Zone 8. Photo | Greenhouse Studio
Propagating Rock Purslane
Love your Cistanthe grandiflora and want to more to plant elsewhere in the garden? It couldn’t be easier to grow from cuttings.
Taking cuttings
Take cuttings early in the day when possible before plants get heat stressed.
Cistanthe grandiflora is so succulent you can just snap off a piece or you can cut it with pruners like usual. Take cuttings with 3 to 4 nodes.
Cut between the nodes (the internode) leaving a stump below the node. This is where the cutting likes to root, so rooting is more difficult if the cut is made too close to the node.
Here’s my Fiddle Leaf Fig demonstrating nodes/internodes. Photo | Greenhouse Studio
After taking the cuttings, dip them in rooting hormone and then allow the cuttings to dry out for a few days to form a callus.
- The callus will protect the plant from most soil-borne diseases and inhibit rotting.
Fill your container with the propagation mix and pre-wet the soil. I pre-wet it because it compacts the mix making the cuttings more stable when I insert them.
“Pre-drill” your cutting holes with a pencil or chopstick. It helps prevent tissue damage and removal of the rooting hormone when you insert the cutting.
Cuttings should be placed deeply enough in the container so they wont’ fall over - about 1 /3 of the way up should do it.
My cuttings are ready to go after applying rooting hormone and sitting for a few days to let the cut ends callus. Callus helps block pathogens from entering and inhibits rotting. Photo | Greenhouse Studio
Succulent propagation soil mixes
Succulent mixes can come in a variety of forms, even propagation media. A common recommendation used by nurseries is to use a mix with a 1:1 ratio of organic to inorganic material. Example: 50% peat or compost with 50% pumice or perlite.
The organic material will provide nutrients and moisture and the inorganic material will provide adequate aeration and drainage which is essential for rooting.
Don’t use animal manure in the mix (included in some heavier landscape topsoil mixes) since the salts in them can be problematic to rooting.
Another good all around propagation media is to use a 50% vermiculite and 50% perlite mix, all inorganic.
The vermiculite functions like an organic material having a high water holding capacity and nutrients of Calcium (Ca), Potassium (K)and Magnesium (Mg).
The perlite provides aeration and drainage.
For my Cistanthe cuttings mix, I took a generic peat type potting mix and amended it with extra perlite to make a roughly 1:1 mix.
I mixed a peat based potting mix with straight perlite to make a 1:1 organic to inorganic propagation media. The organic components provide water holding capacity and nutrients and the inorganic perlite provides drainage. Photo | Greenhouse Studio
Rooting process
Place your cuttings in a bright window if you’re rooting them indoors. Otherwise, keeping them outside under the dappled shade of a tree works well for rooting. Make sure it’s not too shady though which can lead to stretched (etiolated) growth.
Cistanthe grandiflora roots quickly - they will probably form some roots in 2-4 weeks.
You should see some growth at the tip of the cutting once rooting is underway. You can very gently tug on your cuttings to feel if they have formed some roots or not.
You can probably safely transplant your new rooted Cistanthe cuttings into the garden after 1-2 months. Be aware that many other plants would take longer than Rock Purslane to root and be transplant ready.
Check out the video if you want to see the whole propagation process:
My 7 month old Cistanthe grandiflora plant
I wanted to show you what size and maturity you could expect in your cutting after about 6 or so months. Below is a picture of my 7 month old Cistanthe. I cut off a piece on a rainy day in the 8th of December, dipped it in Rootone rooting hormone, and put it directly in the ground.
The reason why was I was having a small planting bed replanted, and I had some succulents I wanted there, but like I said, it was raining and cold, and I just opted for a “throw it at the wall and see what sticks/survival of the fittest” strategy. (I actually do this a lot with plants - I don’t have time for a lot of fuss and coddling with 3 boys, a cat, and a fixer house to also look after!)
So as you can see - it’s now exactly 7 months later to the day actually - July 8, and it’s grown into a full plant measuring 24” across with several flower stalks emerging and one that bloomed for the first time yesterday.
It’s sitting in a spot that gets dappled shade from a low palm tree, and it also gets watered by a less than ideally placed sprinkler head. So it’s not in what you might think would be the ideal spot for a succulent, but as you can see, it’s doing great!
This 7 month old Cistanthe grandiflora (a.k.a. Calandrinia spectabilis) grown from a cutting planted in ground measures 24” across and has several flower stalks emerging (and one that bloomed the day before). Agave americana ‘Mediopicta-Alba’ (left) and Agave Ferox (back).
See Rock Purslane propagation in action on the video!
So I hope I’ve convinced you to give Cistanthe grandiflora a try. I promise it will become a favorite succulent, even if it’s an annual where you live due to cold. (Remember though - they’re rated for growing in USDA Zone 8 - hardy to about 15 degrees F).
As to growing them inside, I found only one reference to it but I don’t see why not if it has a bright window and well draining soil. I’m going to pot up a couple of my cuttings, see what happens over several months, and report back.
If you try Rock Purslane in your garden, a container, or inside, let me know about your experience growing this super succulent in the comments below!
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