How often should I water cacti & succulents?
The single most asked question I receive from followers of East Coast Camanchaca relates to the frequency with which one should water cacti and succulents. It is probably the most daunting of all challenges faced by beginner growers, and for good reason! Watering mistakes can be the most volatile in cacti culture since one single wrongly timed watering could rot your priceless plants.
When I started collecting cacti and succulents, I too was very preoccupied with trying to learn when and how to water my cacti and succulents to keep them healthy and away from root rot. I quickly realized that most of my cactus casualties were being caused by potting soils heavy in peat moss. This ingredient is used across most (if not all nurseries) due to its moisture retention properties and cheap cost, and if you manage to figure out the precise watering schedule for each one of your plants, peat moss probably works great. The issue with cacti is, they go dormant when they experience extended periods of drought and for this reason, we can never allow the roots to stay wet for extended periods of time.
Once I figured out the issue, I set out to ask as many annoying questions as I possibly could to as many seemingly knowledgeable growers as I could. I read about geology and the mineral makeup of the habitats of the plants that I loved and even made the trip to see some of them in the field. I touched the soil, examined the conditions in which they seem to prefer to live and seem to thrive. And from all this, one thing was very clear: even in habitat, it is those plants that are able to drain the fastest after a rain event that thrive and live the longest. All the plants I found with the nicer forms and largest bodies were found on hillsides with the most light exposure (filtered) throughout the day, and lived in extremely gritty soils. All of these similarities, bring us to our next point, not a single piece of advice in cacti culture can be spread across all species and across all environments.
With around 10,000 succulent species of which about 2,000 are cacti, found worldwide except for Antarctica, you can imagine these plants have evolved to survive and thrive in ALL sorts of environments and weather conditions. It is for this simple reason that it would be impossible to cover the needs of them all in a single piece of text. Imagine coming up with a diet plan which worked for the entire human population? Coming up with a cultivation method that worked for all succulent species would be even more difficult as human beings are but 1 species, compared to 10,000 succulent species.
With that in mind, I will do my best to cover the basics which are at least common in many of the most popular cacti and succulent genera. We will cover 3 main pillars of succulent culture: soil, light exposure, water.
Soil
Each and every grower will develop his or her own potting mix over time, as they learn about the cues their plants exhibit when they need more (or less) water. Since each of our cultivation environments is unique to our location, and our own watering habits, our soil recipes also tend to be unique and all seem to work just fine because plants have a threshold in which they can adapt even to less favorable conditions, as long as they are able to survive those conditions. East Coast Camanchaca soil mixes were made to take the guesswork out of this process, and to give beginner collectors a head-start figuring out their unique soil recipe, by adding organic content to the mix (only if needed) and observing their results. No matter what soil you use, start off with low organic content (around 10%) and use very gritty constituents, to make sure your plants are able to drain fast and roots are able to dry quickly and aerate (breathe).
Light Exposure
Just like with soil, plants can adapt to different light conditions to survive even when these are not the most favorable. Cacti and succulents do well with 8-10 hours of sunlight per day, but that extra 2 hours really makes all the difference. It’s also important to mention that even though some plants like “direct sun” that means they can adapt to it over time as mature plants, so for most plants in cultivation you will want to filter the sunlight about 20-30%. I myself use mosquito net to filter out some sunlight. If you start seeing plants “stretch” and grow thin, this is a sign of inadequate light and said plants should slowly be acclimated to increased exposure.
Water
Finally, we arrive at water, purposely leaving it for last as any advice on watering must first take into account that the 2 pillars above are taken care of. In order to thrive a cactus or succulent must first be potted in the correct soil and second receive the appropriate amount of light exposure (preferably 10 hours). If the first 2 pillars are ignored, even if watered correctly a succulent can succumb to rot since it is not able to absorb and metabolize all of the moisture around its roots in time to dry out before the next watering. If the light and soil are correct, you may water your cacti and succulents roughly once each 14 days (this varies depending on species and age of plant, older plants need less frequency) only when temperatures are higher than 70 Fahrenheit, and you have checked the weather forecast to make sure there are sunny, warm days ahead. I like to start watering very lightly after winter dormancy, and increase the amount of water only after the first couple of watering events of the year, as roots need a little time to get started at first. I never water a freshly potted plant (wait 1-2 weeks), and extremely sensitive plants like Lophophora should not be watered during the first month or two after being potted (the larger the plant the longer you should wait).
Check out the video below on the technique I use to water my plants to avoid any moisture landing on the crowns. I do so because I live in a high humidity environment but also because being submerged fully wets the soil and activates the roots. Some growers will leave their plants submerged a full 12-24 hours for the first watering of the year (after winter), but please do so at your own risk as this must be done with the right soil and weather in order to work. As with all plant cultivation advise, always test one plant first in order to detect any issues before moving on to other plants.