Do Indoor Cacti Go Dormant in Winter? The Surprising Truth!
When winter temperatures drop to single digits or go into the negative, you may start to wonder, will your indoor desert cacti become dormant? I was curious about them when I was a beginner too. Cacti are sensitive to more factors than just the heat, so you may be shocked to hear the answer!
Indoor cacti can become dormant in the winter due to 1) decreased sunlight and 2) reduced nutrients. Dormancy happens when cacti stop showing signs of growth and start to shrivel. Keep the cacti in a dry and cool place and avoid watering them during this stage.
Cacti are known to be one of the easiest plants to care for due to their high tolerance for neglect. It can be challenging trying to understand how they become dormant and how this process works. But after this article, you’ll have an easier time understanding it and learning how to care for your dormant cacti!
Can Indoor Cacti Become Dormant?
Most cacti are light-sensitive and will initiate dormancy if their day length fluctuates or decreases, even when grown indoors. Otherwise, if the cactus receives regular sunlight, it will not enter dormancy and will continue growing.
It might be easy to believe that indoor cacti are unaffected and will not go dormant. After all, they’re protected from all the outside elements and are safe inside the warmth of our homes.
Despite this, indoor cacti can still enter dormancy. Surprisingly, the temperature is not the main trigger—it’s the amount of light it receives.
Your favorite windowsill cacti may be warm. But its biological clock will quickly register the shortened day lengths of winter and enter dormancy.
Some cacti owners even notice their plants initiating dormancy as soon as they receive 30 minutes less of their usual amount of light!
That being said, it’s also possible for some cacti to not enter dormancy at all. If your cactus has stable temperatures and consistent lighting all year round, it will continue growing regardless of the season.
How to Identify Dormancy in Indoor Cacti (Signs to Check!)
The most common signs indoor cacti have entered dormancy is when they show no signs of growth or activity despite being given water and care. Some cacti, like pterocacti, can even look dead and require further inspection.
Identifying when your cactus is dormant is oftentimes easier said than done. However, there are some general signs that cacti often exhibit in dormancy to help clue you in.
When winter comes and there are no visible signs of growth such as spines or flowers, it may have entered dormancy.
Cacti that are purchased online are known to become dormant. After being subjected to sudden darkness for days or weeks during delivery, the cacti may briefly enter dormancy to help them stay alive while being shipped.
The same can be said if the plant is not showing signs of hydration even after being watered. They may even start to shrink and become more shriveled as time passes.
Remember, since each species is different, their responses to different environments and lighting will vary.
For instance, many Pterocacti specimens are known to let their above-soil growth die during dormancy, and can seem like they’ve died unexpectedly. As long as their roots are alive and fleshy, they will develop cacti stems again once the dormancy period is over.
To stay safe, I highly suggest confirming what cactus you have to see if it displays unique signs of dormancy.
The 2 Major Reasons Why Indoor Cacti Go Dormant in Winter
The two main reasons why indoor cacti become dormant are 1) decreased sunlight and 2) nutrients.
What might seem confusing and even pointless for us is actually quite strategic for cacti. Despite what you may think, there is some method to this madness.
These are the key reasons why your indoor cacti become dormant despite the weather being warm. What’s more, dormancy can be helpful for them!
1. Decreased Sunlight
Indoor cacti can enter dormancy in the winter when the sunlight is scarce and is not enough for them to photosynthesize with.
As hardy as desert cacti are, they do not thrive in irregular and insufficient sunlight. If they’re kept by a windowsill, they’ll likely receive less and less light throughout the winter.
See this for yourself in: Can Cacti Live Without Light? An Experiment with Photos
However, by halting much of their growing systems, they’re able to enter a state of suspension until their preferred amount of sunlight returns and soil temperature rises again.
Summer dormancy can also occur and help cacti endure the unrelenting sun for days on end. In my opinion, this is much more challenging to identify and control compared to winter dormancy.
Regardless, this is an important defense mechanism that allows them to survive unforgiving events that many other plants would perish in.
2. Reduced Nutrients
Indoor cacti that receive fewer nutrients in the winter will delay their development to enter dormancy. This allows them to rest and preserve their energy and nutrients for the next growing season.
As always, different cacti specimens will have different behaviors. But generally, when desert cacti start to receive less moisture and nutrients in the winter, they will save what little energy they have left.
Rather than use their limited resources to continue developing in unfavorable settings, your cacti will save it and wait for a better opportunity.
This is also beneficial if the plants have been vigorously growing all year round, which will be discussed further later on.
This is why dormancy periods in the winter are also sometimes called winter rest. By becoming dormant, the cactus will save its nutrients for the next growing season and come out even stronger than before!
How to Trigger Dormancy for Indoor Cacti (Care for Them Properly)
Dormancy in indoor cacti can be triggered when they are given less light and water. Keep them dry and cool with limited sunlight to ensure the cacti stay dormant. Near the end of its dormancy, gradually increase the sunlight and water it receives.
Whether you plan to follow the natural cycles of your cacti or help them survive icy seasons, it’s possible to trigger them into dormancy.
To help your cacti enter dormancy for the winter, you can start by giving them less water in the middle of autumn. Once the sunlight naturally decreases in the winter, the cactus will become dormant.
Watering can be tricky, as it depends on your climate and cacti. Most cacti need very little water during this period and are best kept dry.
Keep the cacti in a dry, cool, and dark place, like a basement or a garage, while they are dormant. Regardless of what type of cactus you have or what season it is, air circulation is key in preventing excess moisture from lingering and causing rot or fungal growth.
When the environment becomes more favorable for growth, simply increase the light and water your cacti receive to gradually wake them up.
Discover how to Water Succulents and Cacti The Right Way! [How Often, How Much]
Do Indoor Cacti Need to Be Dormant?
Indoor cacti grow best when they are allowed to enter dormancy every year. This temporary state of rest can prevent etiolation, promote bloom, and is useful in keeping the cacti healthy in the long run.
While it is possible to prevent indoor cacti from going dormant by supplementing them with artificial lighting and regular watering, it may not always be ideal.
If they’re encouraged to grow with reduced or fluctuating light, they’ll likely become etiolated and disfigured. You may argue this can be prevented with an appropriate grow light.
However, by making the cactus grow constantly, they can grow weaker and weaker as time passes. Some specimens require dormancy every year.
Once given proper rest, your cacti will become more resilient to any challenges it experiences. Blooming is also more likely to occur after dormancy, which is a lovely benefit.
It may be tempting to skip dormancy altogether but remember, dormancy is a natural part of the growing process. Even plants need to rest from time to time, so let your cacti go dormant for the winter to help them gather their strength for the new season!
What is the difference between stunted growth and dormancy in cacti?
Dormancy is a behavioral response triggered by changes in lighting, while stunted growth is often a result of pests, disease, or deficiencies. The latter is an unnatural occurrence that can worsen and become fatal for cacti, unlike dormancy periods that are natural and only temporary.
How do you know if a cactus is dormant or dead?
A dormant cactus will eventually return to its normal growth once the lighting and environmental conditions become more favorable. If the roots die and the cactus stem rots and decomposes despite being given proper time and care, the cactus may be dead.
Summary of Do Indoor Cacti Go Dormant
Although indoor cacti may be kept in a warm environment, it is still possible for them to enter dormancy. When the plants receive less light and nutrients in the winter, the cacti will recognize that this is an unsuitable season to grow in and will become dormant.
Each cacti species will behave differently, however, they will generally display signs of slowed or halted growth and become wrinkly and shriveled when they are dormant. Dormancy can manually be triggered by purposefully reducing the amount of light and water the cacti receive.
To ensure cacti stay dormant in the winter, keep them in a dark and well-ventilated area throughout the winter and avoid watering. Typically, it is best to allow indoor cacti to go through dormancy as this allows them to preserve themselves and use their energy for a better growing season.
- “Cacti: Biology and Uses” by Park S. Nobel in University of California
- “A Cactus Odyssey: Journeys In The Wilds Of Bolivia, Peru, And Argentina” by James D. Mauseth, Roberto Kiesling, and Carlos Ostolaza in University of Texas