Cacti get thirsty sometimes. I know this might challenge the idea that most people have: a cactus lives in the desert, then they probably don’t need too much water. The truth is that if you buy or plant a cactus and you want it to thrive, regular watering is key.
Then, how often do you water a cactus?
A cactus shouldn’t be watered on schedule. Instead, follow these steps:
- Poke a finger into the top inches of the soil or the drainage holes of the pot.
- Check if the soil feels dry or if it’s still moist.
- If the soil is completely dry, then water your cactus.
- If the soil is moist, don’t water your cactus.
But how do other factors like the pot size or the weather and seasons affect your cactus’s water requirements? Moreover, how can you avoid overwatering by choosing the right pot and soil mix? These are some of the most important questions that will be answered in this guide.
Determining when to Water your Cactus
Cactus shouldn’t follow a watering schedule (once per week or once per day), instead, you should implement a holistic approach, which is a cactus monitoring schedule.
It consists of checking the soil dryness every other day. Which can simply be considered as the most important task you should develop as a cactus caretaker. Watch the soil carefully and every now and then touch it. This will tell you how healthy the root system and stem of your cactus are in terms of water reserves and if the tank needs to be filled up.
The soil it is still moist – no need to water yet 🙂
If you don’t feel comfortable grabbing a handful of soil or poking your finger into one of the drainage holes of the pot, you can alternatively:
- Get a stick (the length may vary depending on your cactus pot size) and push it into the soil.
- Allow it to sit a couple of minutes before removing it.
- Then, if the stick looks and feels wet, you should wait more days before watering your cactus.
- You can also look for small granular pieces of soil on the stick that give it a black-ish look. This is also an indicator that it still has decent water reserves.
This approach helps you ensure that your cactus only gets water when it needs it. On the other hand, if you lock yourself into a X times per week approach, you could be putting your plant in the risk of root rotting, which can be fatal. In the end, as a rule of thumb, your cactus is better off being a bit dry, rather than overwatered.
Now, there are other factors that have a direct effect on how often you should water your cactus.
Basically everything we’ve found online while researching, all the advice and tips, can be condensed into taking care of the basic elements a cactus might need. These are:
- Light and heat
- The pot or container
- Location: indoors versus outdoors
Light and Heat
Most cacti will do just fine under bright light. Some other species might thrive under direct and intense sunlight. That being said, if your cactus has more exposure to light, then this will make it experience more heat, as more radiation will be produced. This has a direct effect on soil moisture, which will tend to get dry faster.
In general, the more light exposure (especially if it’s direct sunlight), the more often you will need to water or irrigate your cactus.
Light and heat might also be influenced by the seasons, as these have a direct effect on the water evaporation in every plant. During spring and summer, the warm temperatures will translate into higher evaporation and more often watering needs. In contrast, during fall and winter, when the temperatures drop, your cactus and its systems will lose less water due to the environment, meaning that watering should be less frequent.
Also, keep an eye for humidity since the more humid the air is, the less water your cactus needs.
Most experts agree that the most important characteristic when choosing or preparing the soil mix is that it should drain very well. The main reason for this is that good drainage helps to minimize root rotting (more on how to avoid it below), which could put the life of your cactus in danger. A good rule of thumb is to check how porous and light-weight the soil is, since this will give you an indication of how fast it can dry.
The main point here is that the less granular the soil mix is, the less frequent the watering will be.
The Cactus and Succulent Society of San Jose (CSSSJ) recommends adding grit and horticultural-grade sand to the compost element of the soil from your cactus. Keep this in mind when purchasing, planting or repotting your cactus.
The Cactus Pot
Your cactus container has also a direct influence on how often you will need to water your plant. There are three aspects that you will need to consider regarding pots and water:
- The pot size: how much volume of water is needed.
- Drainage properties: how fast can the pot drain the water excess.
- Material: what is it made of.
In the first place, we have the size. Generally speaking, the bigger the pot is, then the more capacity and volume it will have to hold soil, this means that you will need more water to get all the soil to moisten at an appropriate degree.
Here it’s important to mention that you should choose a proper pot size according to the dimensions of your cactus. We suggest avoiding large pots for small cacti, as you could potentially expose it to unnecessary waterlogging.
This takes us to the second point related to pots, which is drainage. It’s very important that the pot has plenty of drainage holes to allow the excess of water to come out. Also, this ensures a proper flushing system to dispose of the waste elements that come out from your cactus. Again, proper drainage will make your plant healthier by preventing root rotting.
Drainage capacity is also tied to the material that forms the pot. For instance, plastic pots tend to retain the water more than terracotta pots, whose porous constitution allows the water to pass by and evaporate, reducing any excess of moisture in the soil and rooting system.
Location: Indoors vs Outdoors
One of the most fascinating features from cacti is that they can thrive in both outdoors or indoors environments. However, depending on where your cactus is located, the watering needs might change slightly.
In outdoor environments like gardens or backyards, there will be more air flowing around. This will carry the moisture from the cactus soil, which can eventually reflect in an increase of the watering frequency that is needed to keep your cactus in good shape.
On the other hand, if your cactus lives in your office or living room, airflow tends to be less, which can make your cactus more humid and therefore decrease its watering needs.
Besides the elements described above, it’s also important to check if your cactus species has specific considerations when it comes to watering. Not all species behave equally. However, this species-specific research is a very important task that you should dig deep into, in order to avoid unexpected consequences.
Here is a link to the cacti database from Home Stratosphere where you can search for hundreds of cacti and learn more about their key specific information.
How to water a Cactus
Now it’s time for the actual water pouring. You might be wondering what’s next after you’ve checked all the vital signs described above and now you know that your cactus needs water.
So the key question here is how much water does your cactus need or how can you hydrate it in the correct way. So let’s get to it.
You should avoid overhead watering your cactus at all costs. This is because some regions of your cactus won’t get the necessary nutrients to function. Instead, water your plant deeply until water runs out of the pot or until the soil gets saturated.
Then you should allow some seconds to pass. This allows the water to properly go through all the soil layers. When water starts coming out of the drainage hole(s), this means that the soil has been soaked properly.
What to do if I overwatered my cactus
Don’t panic. You can rescue an overwatered cactus simply by increasing its drainage. But before you do, please make sure to confirm that your cactus is, in fact, overwatered. The most common symptoms are:
- There are signs of waterlogging or small pools of water in the topsoil layer.
- A weird smell comes out of the drainage holes.
- Your cactus looks turgid or plump.
If one of the symptoms is positive for your cactus, here are some suggested steps to solve the issue:
- Get a clay pot about the same size of cactus, fill it with dry soil mix.
- Repot the cactus carefully, make sure you use newspaper paper and gloves so you don’t pinch your fingers. Here is a good video that I found on how to perform a cactus repotting:
- Allow between 3 to 5 days for your cactus to settle, before you consider watering it again.
If the roots are very damaged from overwatering, you can go for rerooting. This is, however, a more advanced process that requires cutting all the rotted parts from your cactus with a sharp knife.
Once you do that, you should place your cactus to dry for several days until you notice that a scab starts forming on the sections where you did the cuttings. After that, you can proceed to repot the cactus and then don’t water it for the first week. You should monitor its growth and behavior before watering it again.
How long can a cactus go without water?
Short answer: it depends on the species. Several publications have reported that some species that live in the desert can survive for up to two years without water. However, for indoor cacti, it’s a different story. Some anecdotal evidence from users report periods of up to 4 months without it needing water during the winter season
What do I do if I forget to monitor my cactus?
You can set up a daily alarm to perform this task. As with any habit, this takes time to get accustomed. So in order to achieve it, we recommend the habit stacking method suggested by James Clear in his book, Atomic Habits.
This consists of stacking a habit with another recurrent task that you already perform in your day to day life, for instance, you can check your cactus before going to sleep or after having breakfast.
We hope you find this guide useful to learn everything related to how and when to water your cactus and keep it thriving. Let us know your feedback and if you have any extra tips on this topic.