Cacti make excellent indoor plants and are easy to maintain. There are several cactus varieties, and they come in various shapes and sizes. However, like other indoor plants, the cactus will only thrive indoors if the conditions are ideal. So, how do you care for a cactus indoors?
To care for a cactus indoors, follow these tips:
- Choose a cactus variety that thrives indoors.
- Choose a suitable pot.
- Use the correct soil.
- Provide enough light for your cactus.
- Create the optimal temperature and humidity levels.
- Use fertilizer during the growing season.
- Keep pets away from indoor cacti.
- Avoid common errors when caring for a cactus indoors.
- Encourage your cactus to grow faster.
In this article, I’ll discuss how to care for cacti in detail, the ideal conditions, and the challenges you may face. Let’s dive right in!
1. Choose a Cactus Variety That Thrives Indoors
If you’re looking for a beautiful and unique indoor plant, look no further than a cactus, which adds character and beauty to your home. The best way to encourage a cactus to thrive is by recreating its natural environment as much as possible and selecting the right cactus to grow indoors.
A cactus that can survive with partial light is the best variety to grow indoors.
Here are some cactus species that thrive indoors:
| Indoor Cactus Species | Sunlight | Watering | Appearance |
| Bunny ear cactus | Partial | Every 3-4 weeks |
|
| Chin cactus (Gymnocalycium) | Partial | Once a week |
|
| Saguaro cactus (Carnegiea gigantea) | Full | Once a month |
|
| Old lady cactus (Mammillaria hahnina) | Full | Once every 1-2 weeks |
|
| Star cactus/Sea Urchin/Sand Dollar (Astrophytum asteria) | Partial | Once a month |
|
| Easter cactus | Partial | Once a week |
|
| Christmas cactus | Partial | Once a week |
|
| Moon cactus | Partial | Once a week |
|
| Thanksgiving cactus (Crab cactus) | Partial | Once a week |
|
Cacti grow slowly, and you don’t need to worry about them suddenly becoming too large for the pot or their place indoors. Even those that grow big at maturity, like the Saguaro cactus, will grow indoors for a long time before you need to transfer it outdoors.
This video offers insights into how to care for different types of indoor cacti:
2. Choose a Suitable Pot
A good pot for indoor plants, especially cacti, plays a critical role in your plant’s health. Besides getting a pot with drainage holes, you must consider its size, shape, and material.
The pot you choose will support or sabotage your efforts in caring for cacti indoor.
The right pot should be slightly larger than your cactus plant, and it’s best to focus on the roots and the crown. If you’re ready to repot your cactus, remove it from the pot and look at the roots. They should fit in the pot, with some room for growth.
The pot’s width should be 1-2 inches (2.5-5 cm) wider than the current pot and 2-4 inches (5-10 cm) deeper.
The type of cactus and its root structure will determine the depth of the pot. For example, a cylindrical cactus has deep roots, while a ball cactus has short roots. If you use a deep pot for a ball cactus, the roots will sit in wet soil for too long and may start to rot.
| Pot Material | Pros | Cons |
| Unglazed Terracotta |
|
|
| Ceramic |
|
|
| Plastic |
|
|
| Glass |
|
|
When and How to Repot Your Cactus
It may be years before you need to repot your cactus plant. Unfortunately, you may be unable to tell if the cactus needs to be repotted by looking at the plant’s crown. Instead, check for roots emerging through the pot’s drainage holes instead.
If you can see roots growing through the pot, the pot has become too small, and your plant is likely rootbound. This means that it’s time to repot your cactus plant.
You should get a pot one or two sizes bigger than the current one and use more cactus soil because you’ll need to use fresh potting mix when you repot the cactus plant.
Plan to repot your cactus when the soil is partly dry because you’ll have an easier time removing the cactus from dry soil than from wet soil. Get a trowel or kitchen tongs should you need more tools to loosen the soil.
Once you have everything you need, you can remove the plant from the pot, and follow these steps:
- Cover the cactus with layers of newspaper to offer protection against the spines.
- Use a pair of gardening gloves before holding the cactus.
- Gently run a trowel at the edge of the soil to detach it from the pot, and slowly pull out the cactus using tongs.
- Shake off the soil and gently loosen the roots.
- Add fresh cactus soil to the new pot and plant the cactus, ensuring the roots are well covered with soil.
- Wait about 1-2 weeks to water the cactus because it will need to adjust to the new soil before you water it.
3. Use the Correct Soil
When buying potting mix for indoor plants, you’ll discover that cacti and succulents have different soil needs compared with most moisture-loving and tropical houseplants. This is primarily because they have unique watering needs largely dependent on the soil.
Additionally, cacti have shallow roots that need well-aerated soil to absorb water and nutrients. Compact soil can cause problems for cacti, such as root rot, and it’s best to use cactus soil for your plant.
Below is what makes cactus soil unique from other varieties:
- Cactus soil retains less moisture than regular potting mix. The soil is fast draining and mimics desert soil, a cactus’s natural environment.
- Potting mix comprises organic material, while cactus soil has organic and inorganic matter. The inorganic matter in cactus soil is available in higher quantities. It has higher pumice, perlite, and gravel ratio levels than organic material (coco coir and sphagnum peat moss).
- The inorganic material in cactus soil makes it less dense than potting mix. This prevents soil compaction and encourages aeration.
Some cactus varieties, like the jungle cactus, do well in both potting mix and cactus soil. However, it’s vital to use well-draining soil to prevent root rot.
It’s common for gardeners to move plants from the garden to indoor pots, and sometimes it’s tempting to use the soil from your garden. You may get away with this when working with other plants, but you should avoid this with cacti.
Cacti are extremely sensitive to moisture because they have shallow roots that begin rotting when they sit in wet soil. It’s best to use cactus soil because it contains organic and inorganic matter, which increases the air pockets in the soil mix.
Cactus soil is well aerated, allowing it to dry out faster after watering it. The right soil will make maintenance easier, and you won’t need to worry about root rot, especially when you follow the recommended watering schedule.
Cactus vs. Succulent Soil
When shopping for cactus soil, you’ll discover some brands marketing the soil mix as ideal for cacti and succulents. You’ll also find soil especially made for cacti and other varieties for succulents.
This can be confusing because cactus and succulent soils are sold as 2 different products. There are some key differences between cactus and succulent soil.
Although these plants may share some similarities, they differ in the following ways:
| Cactus Soil | Succulent Soil |
| Drains well and doesn’t retain moisture for long | Well draining but retains moisture longer than cactus soil |
| Dry and gritty soil mix (more inorganic material) | Contains more organic material, like peat and compost, for greater moisture retention |
Your first choice of soil for indoor cactus plants should always be cactus soil. However, succulent soil is the next best option if you can’t get cactus soil. It may retain more moisture than cacti soil, but you can water your indoor cactus less frequently.
If you use succulent soil instead of cactus soil, consider using a terracotta pot instead of plastic. Plastic pots retain more moisture, putting your cactus at risk of root rot. If you have no choice, water your cactus less frequently.
You can also prepare cactus soil if you fail to get cactus or succulent soil in the store.
How to Prepare Your Own Soil Mix
Cactus soil is extremely porous, unlike regular potting mix. It drains fast and doesn’t hold water. Commercial cactus soil is fine but not always available. You can make your own cactus soil if you’re concerned about using succulent soil or another potting mix.
You’ll need the following for making a cactus soil mix:
- All-purpose potting soil
- Perlite
- Coarse sand/chicken grit/crushed granite
- Coconut coir/pine bark
- Pumice
Potting soil will provide the organic material. However, it’s best to avoid brands that mention that the soil retains moisture. You should also avoid soil mixes containing vermiculite and peat moss, which retain a lot of moisture, which may be counterproductive when making cactus soil.
Each of the items mentioned above plays a role in the cactus mix. For example, coarse sand ensures the soil mix drains well, while perlite prevents compaction. You may choose to substitute one for the other or even use multiple inorganic materials.
Here’s a popular cactus soil recipe:
- 3 parts potting soil.
- 3 parts chicken grit/coarse sand/crushed granite
- 1 or 2 parts perlite/pumice*
- 1 part pine bark (optional)
*Tip: If you tend to overwater your cactus, using 2 parts perlite/pumice is safer.
This will help improve aeration in the cactus soil and ensure the soil dries out faster. However, if you’re confident you’ll water your cactus correctly, you can add one part to the cactus soil.
After combining the above ingredients, your cactus soil is ready. Ensure you use a pot with drainage holes. The cactus soil may be filled with material that encourages aeration and fast draining, but the drainage holes will ensure the water doesn’t sit in the soil for too long.
If you have any soil left over, you can store it in an air-tight container for future use. Store it in a dry area.
3. Water Your Cactus Correctly
How you water your cactus will determine whether it thrives or dies. Since their roots are susceptible to root rot, the plant shouldn’t be in water-logged soil for too long. Using cactus soil drains water well and helps prevent waterlogging.
You must still follow a favorable watering routine. Most cacti will thrive when watered once every 10-14 days. Some, like the Christmas and Thanksgiving cacti, need to be watered once a week.
Cacti experience the most rapid growth during the spring and summer and need more water during this time. It’s ideal to water your plant every 10 days or as soon as half the pot is dry. It’s best to water it thoroughly and only stop when you notice water trickling through the pot’s drainage holes.
In winter, water your cactus once every 4 to 6 weeks and only when the soil is completely dry.
You should also pay attention to the plant, especially if you’re concerned about overwatering.
Some signs of an overwatered cactus include:
- Changes in plant color, usually yellowish or grayish
- Soft, mushy spots on the stem and base of the plant
- Constantly wet soil
- The plant easily comes apart.
Watering from the bottom isn’t recommended, as this can result in underwatering. Cacti have short roots and may not access the water before the soil dries. Water your cactus from the top, gently pouring water around the soil to ensure even water distribution.
4. Provide Enough Light for Your Cactus
Desert cacti should have many hours of direct sunlight. When growing them indoors, enough sunlight exposure is essential. On the other hand, epiphytic or tropical cacti thrive in bright, indirect light. You need to determine if your cactus plant can tolerate direct sunlight or if it needs indirect sunlight.
The best spot for your desert cactus is a south-facing window because it receives the most hours of sunlight daily. However, your tropical cacti plants will likely suffer sunburn if the area receives too much direct sunlight.
The sudden appearance of brown or yellow spots on your cactus can indicate that the heat is too intense. In that case, you can hang a light curtain against the window or place the cacti 4-8 ft (1.2-2.4 m) away from a bright window.
On the other hand, if your cactus isn’t receiving sufficient sunlight:
- It will elongate to seek more sunlight, resulting in weak stems.
- It may become pale, or if it is colorful, it will turn green. Cacti tend to showcase their vibrant colors when they get sufficient sunlight and bloom because of the light. If the light conditions are too low, they lose their color and fail to bloom.
It’s always best to choose a cactus species that will thrive in your home’s light condition.
Below is a table listing the various types of low-light and bright-light cacti:
| Low Light Cactus | Bright Light Cactus |
| Scarlet ball cactus (Parodia haselbergii) | Angel wing cactus (Opuntia microdasys) |
| Crown cactus (Rebutia) | Saguaro cactus (Carnegiea gigantea) |
| Christmas cactus (Schlumbergera bridgesii) | African milk tree (Euphorbia trigona) |
| Zebra cactus (Harworthia attenuata) | Prickly pear cactus (Opuntia) |
| Fishbone cactus (Epiphyllum anguliger) | Old man cactus (Cephalocereus senilis) |
5. Create the Optimal Temperature and Humidity Levels
Temperature and humidity levels are just as important as sunlight and watering for indoor cacti. Cacti are exposed to high temperatures in their natural environment, and they prefer a temperature range of 70-90 °F (21-32 °C) indoors.
In the desert, the nights are chilly, and hardened outdoor cacti can withstand temperatures that fall to 35-55 °F (1.6-13 °C). However, your indoor cactus may rot if exposed to very low temperatures.
Cacti store water in their stems, the reason you don’t need to water them often. However, this can work against them when exposed to very low temperatures and high humidity levels for an extended period.
An indoor cactus plant’s optimal humidity level can vary depending on the species. In general, desert cacti prefer around 40%, whereas tropical cacti thrive at 60%.
When humidity levels are too low, cacti will start to wilt. If you’ve been watering your cactus correctly but notice it’s wilting, you should check and raise the humidity accordingly. You can either switch on a humidifier or place the pot on a pebble tray with water.
High humidity causes indoor cacti to start having rot spots on the leaves and stems. Over time, the plant will lose its leaves and die. If your home is very humid, you should consider the following to help your indoor cactus plants:
- Avoid watering them until half the pot is dry.
- Use lukewarm water because it mimics desert rainwater, and cacti absorb it better than cold water. This will also help prevent your cactus from rotting.
- Provide your plants with sufficient ventilation. If too many plants surround your cactus, separate them and move them close to a window. Adequate airflow will keep your cactus from taking in too much moisture.
- Use a dehumidifier to control high humidity levels in your home.
Choose one with about a 17-oz (500 ml) water tank, a portable design, and a quiet operation. Besides the benefits to your indoor plants, it also helps to keep your home dry and fresh.
6. Use Fertilizer During the Growing Season
Since cacti grow slowly, fertilizer may not be necessary. However, occasionally fertilizing your cactus will boost growth. It’s best to fertilize an indoor cactus 2 to 3 times a year.
Avoid using fertilizer in winter because, like other indoor plants, your cactus becomes dormant and doesn’t need fertilizer.
Specialized cactus fertilizer is the most suitable to use on your indoor cacti. When you fertilize an indoor cactus, you should use the right fertilizer. If the composition is wrong, your cactus will likely have withered stems and burnt leaves and roots.
Cactus fertilizers contain higher ratios of phosphorus than nitrogen. Apply a slow-release fertilizer with an NPK ratio of 5-10-10 in spring and summer for optimum growth.
7. Keep Pets Away From Indoor Cacti
Pets are naturally curious about plants, and cats can be particularly destructive. Many cactus plants have spines.
Fortunately, cacti aren’t toxic, and your only concern should be the spines. Most pets will avoid cacti once they encounter the spines.
You can also do the following to minimize the risks to your pets and cacti plants:
Keep It Out of Reach
Place your cactus plants out of reach, such as on high shelves or in hanging baskets. Unfortunately, cats tend to be curious until the spines prick them. If you have cats, find a spot where they don’t have support to climb to the shelves or the hanging baskets.
Keep the cactus plants away from your pets’ favorite places as well. Even if the window sill is the ideal spot for your cactus, it’s best to find an alternative space if your pet has already claimed the area.
Use Aluminum Foil
Line the surface near the cactus with aluminum foil. Cats hate the sound of aluminum foil.
You may not hear it, but cats have ultrasonic hearing, which makes them extremely sensitive to the sound when their paws come into contact with aluminum foil. They are also disturbed by the texture and shiny appearance.
Provide Catnip
Ensure your pets have some of their favorite plants close by to take their attention from the cactus. For example, you may consider placing a catnip plant nearby for your cats.
Use Pet Repellents
Scents like citrus, coffee grounds, and peppermint repel cats. You can also use commercial pet repellent sprays to keep your cats away from your cacti.
8. Avoid Common Errors When Caring for a Cactus Indoors
Indoor cactus plants can thrive, even if you neglect them every now and then.
However, there are certain common errors that you should avoid if you want them to have the best chance of thriving:
Repotting Your Cactus in Fall and Winter Seasons
Most nurseries have cacti for sale in the spring, fall, and winter. Transferring the cactus to your preferred pot is usually the first step to take when you take them home. However, it helps to consider the current season.
Winter has shorter daylight hours and lower light intensity. Cacti naturally need bright, indirect light. During winter, the plant is dormant, so you don’t need to worry much about it.
However, newly repotted cactus plants are going through a stage of acclimatization. So, if you repot the cactus plant in winter, the conditions will not support the plant’s need to adjust to the new environment.
The roots won’t grow strong enough to absorb water from the soil. When watering your cactus, the roots may develop root rot, which can be fatal for the plant if you don’t take quick action.
If you buy a cactus in the fall or winter, it’s best to wait until spring when weather conditions change enough to help the plant adjust to the new environment.
Planting the Cactus in a Pot That’s Too Big
Nurseries use certain-sized pots for a reason. Before buying a pot based on its design or because it was available, look at the size of the pot in which the cactus plant came.
There are several reasons a pot that is too large is bad for an indoor cactus plant:
- It takes attention away from the plant. Instead of the cactus, one first sees the soil mix and a large pot.
- You’ll use more cactus potting mix than is necessary.
- Large pots retain water for longer, increasing the risks of root rot.
- It encourages the roots to grow faster while the remaining plant remains stunted.
When repotting, choose a planter that’s one size larger than the current one. A large pot is defined not by its width but also by its depth. If the width of the pot is favorable, but the length holds too much soil, you’ll have the same problems you’d have when using a wide pot.
Tall pots will take a long time to dry, and since cactus plants have shallow roots, the plant will be exposed to conditions that will result to root rot.
Using Unsterilized Soil Mixture
When preparing your own cactus soil, pay attention to the ratio and state of the components. You must also consider that you might plant your cactus in soil infested with pests and diseases.
Commercial cactus soil, or components you intend to add to your cactus mix, such as perlite, may be sterilized. However, it doesn’t hurt to sterilize it before use. Additionally, when you use unsterilized components, such as pine bark, chicken grit, and coarse sand, you should treat them before use.
You can sterilize the soil mix in multiple ways:
Steaming
Steaming is the best way to sterilize soil mix. You can do it with a pressure cooker or steam in a pot of water. The general rule is to steam the soil mix for 30 minutes or until the soil temperature reaches 180 °F (82 °C).
Here’s how to steam soil mix with a pressure cooker:
- Pour water into the pressure cooker.
- Place a rack in the cooker to support the pots with the soil mix.
- Get small shallow pans holding 4 inches (10 cm) of level soil.
- Cover the cooker and start steaming. Ensure you leave the steam valve open to allow the steam out and keep pressure from building in the cooker.
If the soil mix is nitrate-rich or has plenty of compost, steam it for a shorter time (15 minutes). This is because the mix can sometimes be explosive when exposed to high temperatures for a long time.
You can also steam the soil with a pan:
- Add some water and a rack to the pan.
- Place small pans with level soil on the racks.
- Cover the soil with aluminum foil. It is best to cover the individual pans.
- Cover the pot and let it boil.
- Lift the lid slightly to allow the steam to escape.
- Boil the water for 30 minutes and turn off the heat.
After steaming the soil, allow it to cool. Leave it covered in foil until you’re ready to use it.
If you’d like to sterilize your soil in the oven, follow these steps:
- Pour the soil into an oven-safe container and cover it with foil.
- Place a meat thermometer at the center of the soil.
- Put it in the oven and bake until the temperature gets to 180 °F (82 °C). Baking at higher temperatures will cause the soil to start producing toxins.
- Leave the soil covered until you are ready to use it.
Conveniently, you can also sterilize soil using a microwave. Follow the same procedure as the oven, except you now use microwave-safe containers.
You will also need to moisten the soil before sterilizing. Instead of foil, use a lid with ventilation holes.
Here’s what you need to do:
- Heat the soil on high for 90 seconds.
- Remove the container from the microwave and cover the ventilation holes.
- Leave the soil sealed until you are ready to use it.
Using Pots That Are Too Small
It can be tempting to use a small pot for indoor cacti, especially when they have a small crown. Additionally, the plant stands out when it appears bigger than the pot. However, this is a mistake that may cost you your cactus plant.
Cactus plants have shallow roots. Still, even though they don’t grow deep, the fibrous roots can spread wide, especially when they’re constantly underwatered. The extensive roots are vital for the survival of the cactus, and a small pot will naturally lead to rootbound cactus plants.
For example, when growing in its natural environment, a 4.7-inch (12-cm) long Saguaro cactus will have roots that are 3.9 inches (10 cm) deep and spread out over 79 inches (201 cm).
Not Checking the Optimal Conditions for Your Cactus
Since they grow in the desert, it’s natural to assume that all indoor cactus plants need a spot where they can receive bright light and infrequent watering. But cactus care doesn’t involve a one-size-fits-all approach.
Some cactus plants need to be watered more frequently, while some need more sunlight than others. Not verifying your cactus’s optimal light, water, and humidity conditions can cause it to struggle or even die.
Not Allowing the Cactus to Go Dormant in Winter
Most plants go dormant in winter as a defense mechanism. During this period, they conserve the energy they would have used to grow roots and shoots to withstand the cold. During this time, they don’t need additional nutrients.
Instead, they use the sugars and carbohydrates stored during the growing season as nourishment during the dormancy stage.
Indoor cactus plants also need to be allowed to go dormant during winter. In their natural environment, cacti usually go dormant at the peak of summer to protect themselves against heat and drought.
Unfortunately, some people water, fertilize, and maintain regular care in winter.
The result can be:
- Uneven growth since the plant is not getting sufficient sunlight
- The fast depletion of soil nutrients since the plant is forced to grow while it still needs the energy to cope with the cold.
- Failure to form flower buds
Incorrectly Misting Your Cactus
You can occasionally mist indoor cacti, but you need to know if you have a desert or tropical cactus. Desert cacti, like saguaro and prickly pear cacti, shouldn’t be misted.
When you mist desert cacti, you’re encouraging poor root growth, stem rot, and attacks from pests and diseases.
On the other hand, jungle (tropical forest) cacti can do with a bit of misting. However, you should only do it early in the morning or before sunset.
When you mist in the morning, the bright, indirect sun will ensure the water evaporates quickly. The spines are relatively warm in the evening, so the water will dry quickly.
9. Encourage Your Cactus to Grow Faster
Cactus plants naturally grow slowly. However, with the right care, you can speed up the process, see your plant outgrow its current pot, and even witness it flowering more frequently.
Here are some helpful tips for making your cactus grow faster:
Remember to Water Your Cactus in Winter
You may come across guidelines that warn against watering during dormancy, but this will cause the roots to dry and shrivel, resulting in stunted growth later. Instead of cutting off the water completely, you should reduce the amount of water and give longer periods between watering.
For example, you can water after every 6 weeks instead of once every month.
Find a Sunny Spot During the Growing Season
All cactus varieties require plenty of sunlight. However, this is more critical during the growing season. In summer, you should move the cactus to a windowsill or balcony where it will get bright, indirect sunlight.
If necessary, the ideal spot may be outside. However, you should protect cacti from the direct sun, which will scorch them. If the ideal spot gets too hot, you should only leave the plant there for a few hours before moving it to a cooler area.
Use Warm Water When Watering Your Cactus
Cacti absorb warm water better than cold water because it mimics their natural environment, allowing them to grow and flower more effectively. You can even go further by occasionally giving your cactus the ‘hot bath trick.’
The hot bath trick gives the cactus an illusion of the desert’s humid conditions. This can help spur growth, at least faster than the usual pace.
To perform the hot bath trick:
- Water the cactus early in the morning, preferably before the sun rises. Use warm water (68 °F or 20 °C).
- Wrap the plant with plastic.
- Leave the bag on for an hour. The humidity will increase when the sun heats it, leading to improved growth.
- Slowly open the cover. Don’t remove it all at once because the sudden temperature change may shock the plant.
If you’re searching for more information on topic, check out my article detailing a step-by-step guide on flowering a cactus: How To Encourage Your Cactus To Flower (12 Tips)
Conclusion
Once you figure out how to care for cacti indoors, you’ll discover a new interest in adding varieties to add to your indoor plant collection.
You may need to tweak the care to suit your plant’s needs. However, you should always pay attention to your cactus and understand what the changes you see mean regarding its maintenance.
