How to Grow Copiapoa laui – the Smallest Copiapoa

Above are my two original Copiapoa laui around when I first got them – June of 2021. 

The one at the right was not in great shape when I got it, but I didn’t know much better until I saw others for sale. It was stretched somewhat, and not well rooted. I’d thought they just naturally got a bit beat up, but that was not the case. 

At left is one in good condition at the time I purchased it: nice round heads, compact shape, even some bronzing from sun stress. 

I will note that the plant at right can be what happens when the cactus starts clumping and you divide out some of the pups. When I potted up the larger of my two specimens to grow out, I separated out some pups and several were definitely this level of lanky and funky. It’s not necessarily a detriment, but it is worth being aware that the funky look (and smaller roots) just takes a little longer to get established and nice looking.

And almost exactly a year later, this is the same plant! A testament to how quickly they grow – only took a year to reach this size.

Some elements to note: the green color of the flesh of each head,  the fuzz growing in some centers, and at the edges, some elongated heads. Each head is also plump, and you can see that each little segment with a spine areole is segmented and plump. In 2023, we’d had a long, dreary spring, and a lot of cloud cover. Copiapoa absolutely love that kind of mild weather! Despite growing in the deserts of Chile, it’s a relatively cold desert (relative being the operative word there), with foggy mornings and marine layer fog. The same fog that the guanacos and other desert dwellers use to survive – so too do the Copiapoas. 

So…when we experienced a prolonged spring with fog, clouds, but a few hours of afternoon sun, all of my copiapoas thrived. The Copiapoa laui did amazing, and continued to do so. 

I highlight this to showcase what this species really thrives with so you can adapt your placing and potting accordingly. If you’re in a very humid climate, you likely should decrease your organic matter. If you’re in the desert, maybe a touch more organic matter, or plan for more watering. If you live by the coast? You’re golden. 

Water for your Copiapoa laui

Your little laui need less water than you think, but not a complete drought. 

Sure, sure, water when dry. But a better signal is to pay attention to the cactus itself. Are the heads starting to wrinkle and shrink back? Do they look…deflated? 

Signs the cactus needs water! 

 That comes with caveats, though. In winter, especially if the cactus is indoors with supplemental lighting, or if nighttime lows are below 40F, dry is better. If it’s been more than a month or two since the last time it received water, a splash (literally, splash the plant) is enough.

In winter, the cacti are practically dormant, so the addition of water is purely to keep the roots from getting overly dessicated.

Once nights are above 50F and the days get longer, the Copiapoa laui wake up. I will usually do a ‘light’ watering in March or April, as the nights get warmer. I wait until I know there’s a couple of warmer days on the forecast, and then I’ll water just barely enough for the water to sink into the soil. I try not to add enough water for it to completely drain through, but if it does, that’s the reason I wait for a few warmer days to be forecast.

That first watering is just to give the dormant and very thirsty cactus an initial drink. Too much water can cause them to split and scar, especially early on. Worse, if it suddenly gets cold or cloudy, they can rot right as they’re getting through the hard winter season. 

I’ll do at least one or two more of these ‘light’ waterings before thoroughly saturing the Copiapoa in mid to late spring. The gradual addition of water wakes the cactus up slowly, and lets it plump up enough to handle the stress of increasing hours of daylight and heat. 

Fertilizing Copiapoa laui

I fertilize my Copiapoa laui on the same schedule as my other slow growing, desert species – maybe once a month in spring (March through June, ish), then roughly every time I water for at least half of the summer months. 

As summer goes on and the temperatures climb, ironically, I start to fertilize less. I’ll add fertilizer every other time I water, and then as we start experiencing heat waves, I will cut back further. While cacti love the heat and sunlight, going too hot also induces a level of dormancy. My greenhouse will hit 120F in summer, and as it regularly hits such high temperatures, I dial back the food. Too much fertilizer, especially for Copiapoa, creates unnatural growth or can even result in rot. 

I use a balanced 20:20:20 (or 1:1:1) fertilizer for all of my greenhouse plants, including my Copiapoa. If you’re growing yours indoors, or with grow lights, you’ll likely need to feed less often. You can also use a less organic soil mix (more pumice, less soil) and feed a touch more often if you’re not seeing much in the way of new heads being formed, or clear signs of growth. 

If your cactus is looking stretched or elongated, or not obviously growing, don’t feed it. In less than ideal conditions, especially growing indoors, in northern climates, or particularly humid climates, you should dramatically reduce your fertilization. I’d argue that until you see active new heads being produced that are compact, dense, and round, you shouldn’t fertilize your Copiapoa laui at all. They’re fast growing, but not fast enough that they need food if you don’t see growth happening. 

Light for your Copiapoa laui

While hardy and easy to grow in the right conditions, one you cannot compromise on is the lighting.

These need nearly full sunlight for their best growth. They should get some shade midday or during the hottest part of the day, but it doesn’t need to be much. The cactus will start to blush darker if exposed to too much sunlight gradually, but you can’t move them to direct sun too quickly or they’re scorch (as I’ve experienced).

A sign that light is trending towards too much is when the cacti blush a dark purple/bronze color, like the photo at the beginning of this post. Seeing some blushing develop, especially with decreased water, is a good sign they’ve been well acclimated to brighter light – but they still need to be protected from sudden heat waves or excessive sun! 

When they’re a nice, light green, or even a slightly darker green, suddenly exposing them to full sun will scorch them! Fortunately, if you catch it before the burn gets too bad, the cactus will rebound pretty easily. Mine had some scorch damage, but very quickly started to make a new head and new growth. 

My larger Copiapoa laui also suffered a bit of sun damage, and began making new heads and growth from the burnt areas. 

It’s not the end of the world! Even the very old specimen at the beginning of this post had some heads with damage that began making new little cactus heads. I’m pretty sure a bit of burn and regrowth is a natural state for this cactus, especially in our southern California season changes. For the last couple years, we’ve had a very sudden shift from a long, cloudy, dreary spring to suddenly full sunshine and hot days in the space of a week! 

If you’re using grow lights, you want them bright and intense. You might want to scope out your local facebook groups for someone selling marijuana or indoor grow lights that you can use if you’re on a budget, but that may not be as pretty as you’d prefer. Because these stay small, you may be able to get away with using a dedicated, quality grow light in a desk lamp over your cactus. Keep the cactus on the edge of the light at first to test the intensity, and slowly move it to be centered underneath over the course of a week or so. 

You can also use a light meter to check the intensity! Under a grow light with consistent light, it doesn’t have to be as high for a few hours as they may need on a balcony or under patio cover. As an example, when mine were getting blushing but in shade part of the day, they were receiving a whopping 74,000 foot candles of light in the morning – but only from sun up to about noon at most. By noon, their area was in full shade, dropping to just 300 foot candles for the rest of the day. They were also warm! I kept them in a little plastic grow tent, so they were at least 10 to 20 degrees warmer than outdoors. 

Under a grow light, you don’t need to achieve 74,000 foot candles for good growth. You do, however, need to aim for at least 4,000 foot candles, preferably even more so you can adjust if needed. They also need that light for at least 12 hours a day – and for these, I’d suggest upping that to 14 hours during summer, and dropping to 10 or 12 in winter.