Have you ever wondered how to water cactus? Most people are at lost on how often you should really water these plants since they are known to survive in the desert. In this post, find out how often you should water cactus both indoors & outdoors as well as the other basics in watering them.
Cactus are one of the most wanted plants especially for beginners in house planting since they are really easy to take care of.
If you’re a busy person, you might want to have this low maintenance plant too because you don’t need to fret about watering it every day.
However, this fact is also the reason why most newbie cactus owners and even some long-time owners have trouble in how often they should really water their plant.
So, how often to water a cactus? In the simplest sense, you only need to water your cactus when its soil is completely dry. As stated above, cactus need to be watered at least once a week. In fact, some varieties can even survive for as long as two years without water. The appearance of your cactus as well as its potting mix dryness are good indication if you want to know when and how often it needs water.
Of course, there are also a few things to consider if you want to know how often to water cactus.
All cactus have different needs but it mostly varies on your cactus’ size as well as the pot size, the climate and temperature in your area, and the current season. Read on to find more about your cactus watering needs.
How Long Can A Cactus Live Without Water?
No matter how hardy these plants are, they can’t live without water forever. Cactus is a living thing and it requires water to live.
It’s just that cactus can survive without it for extended period of time. In fact, some cactus specie can go for two years without water.
Cactus use the water that they store in the stems and roots much more efficiently compared to other plants. Furthermore, it doesn’t give up its water through evaporation as easily as other plants since it has no leaves.
If the cactus is in the ground, you might it would have deep roots to acquire more water supply.
In reality, cactus often have shallow and extensive root systems that stays just beneath ground and can extend a few meters from the cactus ready to collect as much water as possible.
The plant release more roots once the rain comes and will shrivel back up and break on the drier seasons to help save its water supply.
How long a cactus can survive without water can also depend on the specie of cactus, the size, and the location where it is growing.
The mammillaria species as well as other smaller cactus species can live without problems during the whole winter without water, more or less about four months while they are stored near freezing temperatures to a couple of degrees up during sunny days.
The bigger species such as the Barrel cactus or Ferocactus types can last longer without water for extended period of time since they can be very big, therefore they have bigger water storage.
How Often To Water Cactus Indoors?
It is a known fact that cactus are tough plants that can survive in extreme climates. Their stems and roots act as water storage that will help them survive during extended drought.
However, it doesn’t mean that you should let them go for longer just because of this. Yes, they will survive but they won’t grow to their potential and they certainly won’t thrive.
If your cactus is currently going through its growing season, you need to increase the times in which you water them.
A cactus’ growing season is usually on the warmer months or from spring to fall. Let’s say it’s from March to October, you need to water your cactus once a week or once every ten days.
On the other hand, during the colder months or from October to March, your cactus is past its growing season. You only need to water them once to twice a month.
Factors to consider when watering cactus
There are also a few things that you need to consider to know how often you need to water your cactus.You can use these factors as your guide in watering them.
What species of cactus is it?
Yes, all cactus need less watering than normal plants. However, you can divide the cactus into two types where one needs more watering then the other one.
Cactus can be native in arid areas or in the jungle and the watering differs on both.
These are the types that are native in the desert. It means that they thrive in dry and hot areas even without regular water supply. This cactus type doesn’t need too much watering but will still survive.
From March through September or on the growing season of the cactus, your plant is in the process of growing.
Your cactus needs more frequent watering at this time compared to when it’s dormant during winter.
Examples: Golden Barrel Cactus (Echinocactus grusonii), Prickly Pear Cacti (Opuntia species), Column Cactus (Cereus uruguayanus)
Although they are also hardy, jungle cactus doesn’t like it when they are left to dry completely especially on their growing season on spring and summer.
However, this doesn’t mean that you should leave them with constant watering or they’ll rot.
You can just mist them a few times per week. You can resume to water them once a week when they are dormant in the winter.
Examples: Orchid Cactus (Epiphyllum spp.), Easter Cactus (Rhipsalidopsis spp.), Thanksgiving Cacti (Schlumbergera truncate), Christmas Cacti (Schlumbergera x bridgesii)
What season is it?
As discussed above, there are seasons when your plant is growing more actively.
During summer, you need to water your cactus more frequently not only because it’s hot and water evaporates faster during this season, your cactus is also busy growing so be sure to give them more water.
During cooler months or winter, your plants go dormancy so treat them like they’re resting and decrease the frequency of your watering habits by half or more. They don’t need the extra water when they are dormant.
Is it small or large?
It doesn’t necessarily mean that if you have a bigger cactus, you need to water them more often. In fact, bigger cactus means that water evaporates less from the surface.
What bigger cactus needs is more water because of their size but the frequency should be less compared to smaller ones.
What you need to water more frequently are younger and smaller cactus especially when they are growing in pots to promote higher growth rates.
How much light does the plant receive?
If your cactus is in constant direct sunlight, you might need to water them more frequently.
This is because the heat from the sun lets water evaporate faster, the sunlight can also let the soil where your cactus is planted dry more quickly.
If they are indoors, your plants that are near windows facing the south might need some water more.
Cactus that are positioned near the north part of the house where it is comparably cooler doesn’t need much watering.
Are you using proper Container Size or type for a Cactus?
If your cactus is in a bigger pot, it will take a while for the water to completely dry our or evaporate.
Your plants can also take much more time to absorb the water in a bigger pot. A safe bet is to water cactus in bigger pots every four to six weeks.
Smaller cactus in smaller pots need water too but too much, what they need is more frequency since your plant can easily absorb it.
It is a given that water in smaller pots dry more quickly that bigger pots. Most cactus love it when they are in smaller containers. In addition to this, it is easier to keep your cactus from rotting if they are in smaller pots.
It is also important to take note of the pot that you use. There is more moisture build up if you use plastic pots.
This makes the soil take longer time to completely dry. Just like in succulents, it is ideal to have your cactus in terracotta pots.
Since these pots are porous, water can pass through easily and it provides more breathability.
Whatever type of pot you use, you also must make sure that it has a lot of drainage holes. What you need to prevent is rotting, if your pot has no holes then you’ll surely have this problem.
Finally, note that cactus that are planted in pots need more water compared to the ones that are directly planted in the ground.
Are you using Proper Planting Mix For Cacti Plants Indoors?
The potting soil is important too since it will determine how fast or how slow the water can pass through or be absorbed by both the soil itself and your plant.
What you should look for is any medium that drains fast. Most of the time, common cactus mix is enough for your cactus but you can also make your own by combining perlite, coarse sand, and potting soil.
If you have a good draining mix, you can prevent rot since water can be easily drained as long as you don’t drown your cactus. This also means that you have to water them more frequently.
What temperature are your plants kept in?
Just like light, you need to water more if the temperature is high. High temperatures mean that the water evaporates faster than usual.
Most of the time, it is also when your plant grows more proactively, thus needing more water. Make sure to monitor the dryness of the soil constantly during higher temperatures.
On lower temperatures or during winter, your cactus enters dormancy. You can just leave them be and they’ll be fine even if you just water them every four to six weeks.
Furthermore, you should also take not of the air flow around your cactus. More air flow also facilitates faster water evaporation.
If you place them near or on highly ventilated areas, make sure to constantly check on your cactus too because they might need more water.
How humid is the air?
Even if most cactus like arid environment, they can also thrive if you leave them in the perfect humidity level.
When a cactus is placed indoors, you must check for the humidity especially if the type of cactus that you have is native to arid areas.
In general, you can water less if the area where you placed your cactus is more humid. To be sure, always check if the soil is dry even if indoors.
How often should I water my cactus in winter?
As stated before, treat winter as the resting season for your cactus. If your cactus is in dormant period, you need to water them even less than usual.
For instance, a safe estimate is to water them once every four to six weeks or just once a month. If the cactus that you have is native in the jungle, it’s fine if you add a bit of misting here and then every winter.
Basically, your cactus just need enough water to get through winter. If you mostly have cactus that are native in arid areas, take extra care since they don’t adapt well on cold dry winters.
How to Tell When it’s Time to Water Your cactus: Signs Of An Under-Watered Cactus
So, you get the idea not to water your plant too regularly. Then, how would you know when to water your cactus?
As an owner, you should know when your plant is in distress. If your cactus is in dire need of water, you might notice a slight discoloration on the overall appearance of it.
Most of the time it looks brown and dry. It would also shrink, shrivel, and pucker if it’s under-watered.
You don’t need to wait for visible signs of an under-watered cactus before you actually water them. To know the optimal time when to water your cactus, check these steps:
Basically, what you’re looking for is a dry soil before water. Don’t just look at the top or bottom of the soil or potting mix, check for the inside too since it can still be wet.
Can you overwater cactus?
Let’s discuss the other extreme, if you’re still a newbie and you’ve found out that cactus need water too, you may overcompensate and water them more than what’s necessary.
Believe it or not, it is better to under-water your cactus compared to overwatering them.
It’s harder to turn back from overwatering a cactus since most of the time, it will lead to rotting. Remember that they store water on their own so you don’t need to fuss about watering them constantly.
Am I Watering My Cactus Too Much: Signs of Overwatered Cactus
It can be quite tricky to spot an overwatered cactus because if you look outside, your cactus might look really plump and healthy.
In fact, they can even show new growth. You won’t notice that the problem is on the roots. If your cactus is overwatered, the roots will surely rot and it can hard to revive them.
In some instances, overwatered cactus can show brown spots on the outside. They might also look mushy if they have too much water.
On some cactus like saguaro and barrel. You might notice that the seam that connects the ribs on your cactus will start to split open when they are given too much water.
In time, the scab or split will explode especially in the summer. On the other hand, you can also have some freezing problems on your overwatered cactus in the winter.
How to Save an Overwatered Cactus?
If the rotting is not yet deep and hasn’t affected the cactus entirely, there might still be a chance to revive them.
Be sure to remove any rotting parts to make way for regeneration of a whole plant. Furthermore, the rot may spread if you don’t remove them.
Before repotting the cactus, make sure to let it heal and dry in a dry area for a few days.
Should I mist cactus?
It’s okay to mist cactus especially if you have the ones that are native in the jungle. On the other hand, you must not mist your cactus especially the desert cactus.
They are not used to surface moisture unlike the jungle types. They usually get the moisture that they need from their roots.
On the contrary, some plant owners believe that you should not mist cactus since there’s a huge possibility to overwater them.
Furthermore, they also believe it is quite useless to mist cactus since they don’t absorb water from with bodies.
A good practice is to watch for your cactus’ reaction to misting, also check for the type the you have.
It’s a bit tricky since Christmas cactus love a bit of misting daily. Eitherway, they can go with or without it, depending on your choice.
How to water cactus
There are different ways that you can water your cactus. If your plant is placed in a pot.
Some prefer to water their cactus by submerging them completely in water. Most of the time, this method is applicable for cactus that has big and thick roots.
This next method of watering is much more simple. You only need to apply water at the surface of the soil.
The amount of water that you use in this method should depend in the area where your cactus is placed, as well as the heat and sunlight. Let the water drip down the drainage holes.
No matter what method you choose in watering your cactus. Always remember not to overwater them. Also remember that type of cactus that you have to guide you in watering.
What kind of water should I use in watering cactus?
In general, your cactus is not picky when it comes to water. In fact, tap water works just fine but if you happen to collect rain water, it is much more preferable.This is because some tap water has varying quantities of dissolved minerals that can be harmful for your plant.
Other tap water has chemicals such as chlorine and fluoride too. These components can cause some build-up on your plant’s soil and roots that can block the necessary nutrients that your cactus should be getting.
Lindsey Hyland grew up in Arizona where she attended University of Arizona’s Controlled Environment Agriculture. She has supplemented her formal education by working on various organic farms, including spending a semester abroad in India.
Growing and/or raising just about anything gets her excited. She is especially passionate about environmental justice and low-tech, sustainable ways to better run small-scale farms and homesteads. Lindsey started Urban Organic Yield to discuss gardening tips and tactics.
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