The Stenocereus beneckei is one of those cacti that when you see one grown in greenhouse conditions, or sheltered from natural rainfall, it absolutely takes your breath away. The ghostly pale body and stark contrast of the spines draws the eye no matter who you are.
That powdery coating is only there on new growth, easily brushed off with a finger or washed off with water. When grown outdoors with exposure to the environment, the bloom disappears almost entirely, showing a gray-green flesh that is not particularly remarkable. Older spines fade from the vivid red of new growth to a bland gray, which occurs even in greenhouse-grown specimens.
Origin
Stenocereus bueneckei is native to central Mexico, where it grows on the sunniest parts of rocky cliffs. Knowing that they grow on cliffs gives a hint as to a probable reason for them to evolved with the powdery coating on new growth: it protects the growth from the intense sunlight before it has time to harden!
In habitat, they typically grow in a shrubby habit, with many arms and often semi-prostrate.
They are well adapted to their scorching summers, and take advantage of rain and warm weather with rapid growth any opportunity they can. All through warm weather, with the slightest hint of moisture, they’ll grow.
Cold nights and low daytime temperatures will put a pause on new growth, as will dry conditions.
My Stenocereus bueneckei in May 2022, showing the new-growth powdery coating on top, and what’s left of the original coating on the lower body portion.
When I first got my Stenocereus bueneckei in October of 2021 as a cutting from @cactusupdate on Instagram
Same cactus just shy of a year later: end of August, 2022. A LOT of growth for one year!
Cultivation
Growing the Stenocereus bueneckei
Soil
As a rapid growing species, they are pleasantly un-fussy about their exact soil. The most important element, as ever, is that it be fast-draining. I over-potted mine, expecting that it would grow quickly and hoping to avoid re-potting it too quickly.
I used a mix of 50% pumice and 50% cactus soil, in large part because I was over–potting it, and because I wanted it to be able to stay in the pot for an extended period of time. With more inorganic medium in the mix, you get more time before the soil compacts and stops absorbing water, and the porousness of it allows you to water with a carefree frequency.
If you don’t mind repotting and potentially ruining the powder covering of the growth, you can use regular cactus soil and just expect to repot every year or two in spring.
Main considerations are that your soil drains quickly – when you pour water in the top, it should come out of the bottom relatively quickly. It should also dry quickly, a sign that there’s airflow in the soil. If you water on Sunday, ideally, the soil should be dry or nearly so by Wednesday.
My cactus in June 2022. As we began getting hot weather, the Stenocereus grew faster. Interestingly, unlike some other columnar cacti I’ve grown, the base also plumped with time.
Water
In summer, with plentiful sunlight and warmth, you almost can’t overwater your Stenocereus bueneckei. I realized with mine that they readily enjoy as much water as you’ll give them, so long as the soil is dry before you water again.
For me, in the greenhouse, this could be every few days. During heat waves, I would aim to water 2x a week – less than last year, when all my plants were acclimating, but certainly more than usual.
In cooler weather, keep dry. Mine gets reduced water through fall, and this year, I stopped fertlizing in early November when our nights started regularly hitting 50F. With the greenhouse helping, daytime highs are still regularly hitting over 90 if it’s sunny out, so I’m still providing regular water about once a week, moving to every other week or less as we enter the time of year with the shortest nights.
Fertilizer
During the growing season, these do appreciate a dilute balanced fertilizer on a regular basis. I noticed the most significant growth when I adopted a regular fertlization routine in summer. I use an inexpensive generic blue-colored powder in a 20:20:20 ratio, diluted to half strength, once a week all summer.
I do not fertilize aside from the hottest and longest days of the year. If you water too much and feed too freely during shorter days, the cactus can actually stretch and look lanky from inadequate light.
My Stenocereus bueneckei,
November 2022.
Lighting
These cacti absolutely thrive in the brightest exposure you can give them. The brighter their exposure, the more powerdy white coating you’ll see, and the more rapid their growth.
If you can, keep them in a single, stationary spot in your greenhouse or sheltered area. Ideally, they’ll be in nearly full sun, but avoid rotating their pot. They’ll grow in a very slow spiral, their apical growth points facing the sun and how it moves in the sky. That slow spiral only happens if you always keep the pot facing the same direction, though, over a long period of time, which is harder than you’d think.
Full sun, full stop. They love sun, they love heat. The more you can give, the better. In more northern latitudes, supplemental lighting may be needed in winter – or ensure they go dormant with cold weather & dry soil!
Up close and personal with the powdery coating of the Stenocereus bueneckei. This stays on the flesh as long as nothing disrupts it. Some of the pattern seen here can be attributed to mist from using the hose to water nearby, spraying pesticide, or even just humidity in the greenhouse leading to a slight condensation layer on the plants.
Worth the effort
I absolutely love this cactus. If my greenhouse were on fire, this is one of the plants I’d run in to save. Over time, it should grow branches, and develop into the columnar shrub that they are known to be.
Pests
I keep mine protected from pests with a twice-yearly (winter and summer) systemic pesticide I spray on the top dressing and lower 1/3rd (which is already ‘ruined’ for the coating due to collateral damage from my hose), and then on alternate timing (spring and fall) with beneficial insects. Lacewing larvae and predatory mites are my preferred methods of natural pest prevention. When I refresh my systemic and border pesticide during temperature extremes, I also replace a no-pest strip I hang in the middle of the greenhouse.
My area has a severe problem with ants, which means they are prone to carrying in aphids and mealybugs anywhere they can get in. While beneficial bugs help in mild weather, in summer especially, the heat seems to kill just about everything still inside during the day – except pests, of course. In winter, it’s too cold for most beneficial bugs to stick around at night.
Healthy plants also resist pests much better than those stressed by inadequate water, light, or poor soil.
Get One if You Can!
Because they are so coveted once someone sees them, they are hard to get and often pricey when you do. I find them worth the price tag – my year-old cutting is just now reaching an impressive look, and it’s hard to say when or if it’ll branch out.
In the realm of propagation, they’re slower. They take more work to establish the cutting, and it’s the rare person willing to chop and prop their prized Stenocereus.
These are also a night-blooming species, although mine has yet to do so. They are supposed to be easy to grow from seed, but I’m not sure if they need to be unrelated plants that bloom or if you can prop a single plant and fertilize from those flowers.
If you know the answer, find me on Instagram and share! @TrexPlants – and follow me to see more updates on this ghostly beauty.
