Cacti love heat and low humidity, but many people growing them experience cold winters and high humidity in winter. In those conditions, your cactus or cactuses will need a dormancy period in winter. In this post, you will find a full guide to cactus dormancy and tips for cactus winter care – light exposure, watering and more.
When is cactus dormancy period?
Cacti in their natural habitats (mostly North & South America) get hot temperatures in summer, where they also don’t see much rainfall. So, they stop growing in summer (dormancy) and continue their growth in mid-fall, with the start of rainy seasons.
Because most cactus owners keep their cactuses indoors, they experience warm-hot summers, but cold winters. In this case, you need to initiate dormancy in your cactus in winter (mid October-end February).
If you keep your cactus indoors, it’s important to allow them to go dormant in winter. Dormancy allows cactuses to ‘rest’, form their buds for flowering and prepare for growth in summer.
Do all cacti need a dormancy period?
No, not all cacti need a dormancy period. Desert cacti will benefit from a dormancy period at home. Tropical cacti, such as Rhipsalis or Schlumbergera genus of cacti or Epiphyllum cacti, do not need a dormancy period.
For tropical cacti, please make sure temperatures are a bit higher during the dormant period. Ideal temperatures for tropical cacti during winter is around 54-59 F (12-15 C).
Tropical cacti also love higher humidity and experience it in their natural habitat. So, during dormancy you can mist the plants from the top.
Cactus dormancy instructions
Step 1: Reducing watering frequency
The first step to starting your cactus dormancy period is reducing how often your water your cacti. This is very important, as lowering watering will help protect your cacti’s roots from drying and dying.
It will also help prevent rot, as water evaporation will be low in cooler temperatures (next step). Make sure to reduce it gradually. If you were watering your cacti once in 2 weeks in summer, reduce to once in 3 weeks in early fall and then only once in 4-6 weeks in winter.
Never stop watering dormant cacti altogether – this will lead to root loss and stunt their growth. Light watering in winter will help to keep your cactus alive. You can test the moisture in the soil by using a soil meter like this.
Read about watering cacti in this post.
Step 2: Move your cactus to a cool and dry area
The second step to wintering your cactuses (letting them become dormant), is moving them to a cool spot. Towards the mid of October, when temperatures start getting lower and lower, you need to think about moving your cactus to a cooler spot.
Cactus dormancy temperatures should be around 47-54 Fahrenheit (8-12 Celsius). If you have kept your cactus indoors through the year and have heating, you need to move it to a balcony/garage or even outdoors. You must not keep your cactus in a warm/hot room in winter.
Not moving your cacti to a cool spot in winter will stop them going dormant. It will continue growing (but growth will be uneven and minimal).
What is more, it will be evaporating water due to higher temperatures, and drying as a result (as you will water it less). What is more, the area should be dry. You will then notice thin and elongated growth on your cactus.
Keeping your cactus in lower temperatures will decrease water evaporation and general metabolic processes in your cactus. Growing through the winter will disturb flower bud formation, cause nutrient depletion and drying of the cactus.
Step 3: Keep your cactus in cool conditions for winter
Once you have moved your cactus to a cool area, keep it there until the end of February. Your cactus will be in resting mode, and its growth will stop. Keep them in a spot where they can get as much winter sun as possible.
Once temperatures start going up again, you will need to slowly introduce your cacti to sunny conditions. But this must be done gradually.
Because your cacti won’t experience bright sunny conditions throughout the winter, sudden sun is likely to burn them. Cacti adapt to low light conditions, so gradual re-introduction is important. What is more, do not fertilize your cactus in winter.
You won’t be really able to tell if your cactus is dormant. However, no growth = dormancy.
Step 4: Slowly introduce to sunny conditions
After winter dormancy period, around March, you must gradually introduce your cacti to sun to prevent burns. To do this, place them on a windowsill or other permanent/usual location.
Then, use a white gauze or a thin cloth to shade your cacti from full sun. Over the course of few weeks to a month, as weather gets warmer and amount of sunlight increases, you can expose your cacti to more and more sun.
If you don’t shield your cactus from direct sunlight after not getting much sunlight in winter, it will burn the plant. It will affect epidermal tissues of a cactus, leading to disruption in crucial metabolic processes, and even death. Make sure to provide decent ventilation as well, as cacti hate stagnant air.
Please limit sun exposure and watering for a week if you have just re-potted your cactuses into new containers. What is more, don’t increase watering too suddenly – gradually increase it as temperatures rise too. Gradual changes in the environment is what will guarantee a successful dormancy for your cacti.
You can read more about cactus light requirements and re-introducing to light after winter here.
Important tips for dormant cacti
#1: Water temperature
Don’t water any cacti, especially dormant cacti, with cold water. Cold water is very bad for the roots, and cacti won’t absorb cold water. That can easily lead to rot in cold weather. Ideal water temperature – 86-104 degrees F (30-40 degrees C).
Always check the soil before watering – insert a wooden stick to check. For tropical cacti, you can also mist them, to mimic natural higher humidity.
#2: Watering frequency
Water dormant cacti around once a month or 5-6 weeks. Dormant cacti also need some water, otherwise they will dry and lose roots. Check the soil before watering.
If you repot your cacti when dormant before growing season starts, shield from bright light and don’t water for at least a week after. The best time to repot it would be by the end of dormancy period, so it can start new growth.
You can read more about repotting cacti in this post.