July 9, 2019

So you Killed a Cactus? ~ Summer Rayne Oakes


I don’t typically take house calls when it comes to people’s missteps in plant parenthood, but a good friend said his colleague at work was quite distressed about a “situation” with his cactus and wondered if I could find some time to swing by to diagnose it.

The office space wasn’t terribly out of the way, so one afternoon, I decided to pay a visit to check on the status of the cactus. It turns out that the cactus didn’t really belong to the person who was distressed, but actually to his good friend, who—as I found out through a little probing—had moved away. The cactus was the one physical link he had to their friendship.

Seeing that he was now the surrogate caretaker of this cactus, which ultimately held deep personal significance to him, the signs that it was…perhaps…dying, panged him. “My intention,” he shared with me in his soft voice, “was to give it back alive and well.”

Instead, part of the Opuntia was browning and one whole decaying “arm,” or pad, of the cactus had fallen off—or been removed—as if suffering from a form of leprosy.

Succulents, like cacti, are often said to be some of the easiest plants to care for in the home, but that’s not always the case. This can be the case, however, provided that you give them the right conditions and just a little attention. (Note: Ask what the plant wants from you—and not what you want from the plant!)

I couldn’t quite get the full story of the cactus in question, but the one thing I had noticed was that although this one was in a western window, the window was screened from any bright light (something this cactus would need) because it faced another building. Additionally, I probed my pointer finger in the soil, which was covered by decorative stones, and found it to be rather impenetrable and dry—not porous and airy, which is necessary for all plant roots, since roots, like stems and leaves, need oxygen.

I suggested that we take the cactus out of its planter to clear the soil and see if there were any living roots left. A close inspection showed no roots at all, but luckily, cacti are quite resilient, and I suggested that he might want to take a cutting of the pads that were still green and let them suberize, or harden over—(this helps reduce the chances of a cactus rotting)—and repot them up and start the growing process over again, while providing the plant some more optimal conditions, which I’ll touch upon below:


As I’ve already established, having bright light for longer periods of time is critical for growing most desert-dwelling cacti (unobstructed southern or western exposures if you’re in the northern hemisphere is ideal).

This will give the optimum conditions if you want healthy plants, though through observation and experience, I’ve found that some of my cacti—particularly in the summer months—can get stressed with intense light, particularly if you’re not giving them enough water. You’ll want to water your plants in relation to the quality and quantity of light you’re giving them.


A good, general rule of thumb for watering your cacti is water weekly to biweekly during the growing season, and then withhold water November to March in the non-growing season—that is, if you have a winter like I do in New York. However, I always think observing what your plants need is the best method.

Recently, I walked into my dentist’s office, who has a number of beautiful succulents in her south-facing window. One in particular was looking a little desiccated, so I suggested that she water it a little and pull it back from the direct light. It worked wonders!

Water your cactus thoroughly enough for the water to come out of the drainage hole. Don’t pour water too fast into the container because most succulent roots are shallow and can easily be exposed to the sun or broken.

Soil Mix

If you’re considering getting a cactus for the home, then you’ll want to invest in the right kind of mix, which has good drainage and is lightweight.

I get a “Succulent and Cacti Soil” from my local plant shop, which is a soilless mixture of horticultural grade peat humus and sphagnum moss, perlite, earthworm casings, and mycorrhizae. If you get anything heavier, then you’ll likely suffocate or rot the sensitive succulent roots when watering.

One cautionary note is that peat-heavy mixtures tend to dry out quickly—and if they do, they are hard to rewet, which is what I believe happened to the caretaker’s Opuntia. You want to make sure that the soil around the succulent isn’t dry and dusty. Even if you are watering regularly, the soil can be so “repellent” that the roots may never get wet—and ultimately end up desiccating.


Though I’ve grown many cacti successfully in all sorts of planters, I would generally encourage the novice cacti grower to get a terracotta planter pot with a drainage hole and saucer, because if he or she has a tendency to overwater, at least the water will drain through the bottom or be wicked away through the breathable terracotta pot.

However, I have most of my succulents in upcycled or recycled tea containers, which have absolutely no drainage holes. I am careful to observe which plants need water and take care in watering the plant well—but not enough for the soil to stay wet. That typically means watering around two-thirds or three-quarters of the way.


Surprising to some, cacti can go dormant at different times of year.

The important thing to note is that because they’re dormant, they are going to be subject to their environmental surroundings, and if it’s hot and dry, transpiration, or the evaporation of water, will be happening from their swollen stems, and that will need to be replaced through watering.

Though I generally withhold water during the dormant season, I found that it was still wise to water on particularly sunny days in winter.


One of the major benefits of having cacti in the home is that they are relatively pest-free. I have, however, seen mealybugs, which are a common cottony white scale, on some of my cacti, and this will eventually compromise the health of the plant if it’s left unintended.

Generally, you can just wipe them off with your hand (watch any prickles!) or dip a Q-tip with some isopropyl alcohol and dab them off the plant carefully. You can also use a horticultural oil spray, but be certain not to put the plant directly in hot sun afterward, because that can damage the cactus. Follow up periodically to make sure the plant is pest-free.

Hopefully these basic tips will have you feeling confident about bringing and caring for a cactus indoors.

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