The Wondrous Variety Of The Indoor Cactus

If you feel you have a black thumb, and you’re always letting your houseplants get too dry, leaving them for weeks without water, there is a solution.

The trick is to pick the right kind of houseplants that suits how much time you have, and what you tend to do to your plants, whether that’s leaving them to their own devices, or babying them a little too much.

If you find yourself forgetting to water your plants often, indoor desert cactus plants might be the kind of houseplant you’re looking for.

But maybe your home doesn’t have a lot of light, and you tend to overwater your plants, in which case, tropical cactus plants would be better.

Interested in growing some cactus plants indoors? Not sure what would suit your home? Here’s everything you need to know.

Indoor Cacti: Desert Or Tropical?

There are many species of cacti you can grow indoors, and exactly what you should pick boils down to one question: desert or tropical species?

For very dry, very sunny window sills, cactus plants that are native to arid areas that get a lot of sun but not much water are perfect. 

Largely, these plants do well with very little attention from you and will survive in suntrap windows where other plants would wither and burn.

If you want to add more life to a humid and warm bathroom, with indirect light, a tropical cactus is a perfect way to do it. 

Tropical species can’t stand as much direct sunlight as cacti species, and they won’t do great in very dry rooms, as they are used to some humidity.

Desert cactus species will decline in rooms that are too humid, as well as in light levels that are indirect with little to no direct sunlight (see also How To Care For The Boobie Cactus).

Ideal Light Levels For Indoor Cacti

Depending on which sort of species you go for, this will dictate the sort of light levels your indoor cactus needs.

Put your cacti plants as close to a window as possible without touching the glass. For cacti that come from arid regions, you’ll need to make sure this is a window that gets at least four hours of direct sunlight a day, but for the most part, this won’t be enough.

You may want to invest in a grow light to keep your desert cactus happy.

As for tropical cacti, these plants prefer bright and indirect light, though most of them will be happy with a few hours of morning sunshine, which will help keep them healthy.

Ideal Soil For Indoor Cactus Houseplants

For the most part, indoor cactus plants will do well with compost mixes that are specifically formulated for cacti and succulent plants. 

For better and stronger roots, use a mixture of equal parts cacti compost and horticultural grit, which sharpens the drainage and gives the plant plenty of oxygen.

For tropical cacti, this kind of drainage can be a little too much. Use a standard houseplant compost, mixing two parts compost with one part perlite or pumice

Whichever cactus type you go for, it’s a good idea to add a thin layer of horticultural grit or fine pebbles to the surface of the soil. 

This helps keep any stems or leaves that might touch the surface from rotting, and it can also help prevent pests.

When To Water And Feed Houseplant Cacti

Again, exactly when your cactus plant will need water depends on the species, and the conditions it’s used to in its native environment.

Tropical cacti species will need water more frequently than desert species. Allow the top inch or two of soil to dry out in between watering.

For desert species, the watering regime is much more low maintenance, but you will need to water deeply each time.

Allow the soil to completely dry out in between watering, and then water deeply at the base of the plant, careful to saturate the soil without splashing water onto the plant itself, as this can cause rot.

Scale back watering for your indoor cacti when fall comes, and for desert cacti, you can stop watering them completely in winter, allowing them to go dormant.

For tropical cactus plants, don’t allow them to go completely dry during winter, but allow the soil to mostly dry out.

It’s useful to feed your indoor cacti a couple of times during the growing season, as this helps keep the growth balanced. 

Use a cactus and succulent feed, following the dosage instructions on the label. Feed your plant every fourth watering or so during the growing season, paring this back in fall, and stopping completely in winter.

Pruning And Propagating Indoor Cacti

Cactus houseplants don’t need pruning very often. The only times you’ll need to do so is when parts of your plant are damaged or diseased, or when you want to keep your plant at a more manageable size.

Whatever pruning tools you use, whether that’s scissors, secateurs, or a knife, make sure they are sharp and sterilized. A clean cut makes all the difference, as it helps prevent infections.

Only prune your plant during its growing season, which is usually spring and summer. Leave the plant alone while it is dormant.

If you want to propagate your plant, there are several different ways depending on the species.

If your plant has several growth points or plantlets, you can divide the plant when repotting, potting up each division separately.

For trailing tropical cacti, you can take leaf or stem cuttings, and for desert cacti that have long stems, you can cut a portion off at a 45° angle. 

Whatever type you have, it’s important to set aside cuttings for a couple of days before you pot them up in cacti soil. 

Allowing them to air dry helps close up the wounds, which also means that when you plant them up, they are less likely to drown as they cannot take up so much water.

Once your cacti props have air dried, pot them up in suitable compost, somewhere bright and warm. 

Cactus Varieties To Grow Indoors

There are plenty of cacti species to try when you want to add some interesting and easy plants to your home, but remember to choose one that will suit the space you have in mind.

There’s little point in buying a desert cactus if you’re wanting to grow it in a humid kitchen or bathroom that doesn’t get a lot of sunlight, for instance.

Just something to keep in mind. Here is a selection of some of the most beautiful cacti you can grow indoors, as a jumping-off point.

Acanthocereus tetragonus ‘Fairy Castle Cactus’

One of the most interesting cactus plants you can grow indoors or out is the Fairy Castle Cactus, also known as Acanthocereus tetragonus. 

It produces lots of offsets at varying heights, creating a clump of turret-like stems which look a little like a castle!

It is well worth keeping this plant well away from pets and children, as each stem is covered in spines, so you might also want to keep it out of a high-traffic area.

If this plant wasn’t unusual enough, it comes into its own when it produces flowers in shades of white or yellow, opening at night. 

You will have to be patient, however, as the plant has to be mature, at least ten years old before it will bloom.

This can be a rare sight indoors, and only if the plant gets enough sunlight, so you may want to put this plant under a good-quality grow light.

The Fairy Castle Cactus will do well on a very sunny windowsill, with direct sunlight for most of the day. It can also be grown outdoors in warmer areas.

You’ll soon know if the plant doesn’t get enough light, as the vivid green will fade, and the column-like stems will be thinner, weaker, and stretch towards the light.

Don’t put this plant in the path of drafts or near heat sources, as fluctuating temperatures can cause problems. Keep the plant somewhere warm and bright.

When watering it, be careful not to get water on the stems, as water left to pool on the cactus will rot the plant. Only water it when the soil is dry, and water it deeply to mimic the plant’s native conditions.

Astrophytum asterias ‘Star Cactus’

Sometimes known as the Sea Urchin Cactus, Star Cactus, or Astrophytum asterias, this is a gorgeous plant that’s perfect for small, sunny windowsills.

This species features a star-shaped plant that is spineless, and more often than not, it won’t get any bigger than four inches wide.

Astrophytum asterias is a striking plant that can go for months without needing any attention from you, provided that you give it at least 6 hours of sunlight a day, as close to a window as possible.

If that’s not possible, turn to a good-quality grow light to give the plant the light it needs.

Keep an eye out for dry, brown spots appearing on your plant, as this will tell you that your Star Cactus is getting too much sunlight.

This plant is used to prolonged dry spells, broken up by heavy rainfall, and the plant itself acts as a storage organ for water, so you can leave it to its own devices for a good while without worrying about it.

Always let the soil dry out completely before watering the plant deeply, and allow any excess water to drain, tipping out any that collects in the bottom of the pot or saucer.

Overwatering is the biggest killer of this species, so if the soil isn’t dry, wait until it is before you pick up that watering can.

Scale back watering once fall arrives, and avoid watering it at all in winter. It will hold until spring when you can gradually increase watering again.

This plant will also flower, producing cheery yellow flowers with shades of red and orange in the middle, but you’re unlikely to see these bloom for a few years until the plant is mature.

Disocactus flagelliformis ‘Rat Tail Cactus’

If you prefer trailing cactus houseplants, you’re in for a treat. The Rat Tail Cactus or disocactus flagelliformis produces stems that can reach 5 feet long, blooming in abundance in spring and summer once the plant gets old enough.

It will take time to get to that length, as it is a very slow-growing plant, so don’t worry about it quickly outgrowing your space.

This is not a plant you want to keep near curious hands, paws, or mouths, as each stem is protected by brown thorns! With time, the hair covering the stems will turn white.

Bright light is a must for this plant, as it needs some direct sunlight to thrive. Typically, morning sunlight is not enough, so opt for a Western-facing window.

Allow the soil to completely dry out in between watering, and put a Rat Tail Cactus in a warm room, with temperatures between 60°F and 70°F.

Soil with decent drainage is also a must, as this plant is used to long dry periods in its natural habitat. 

Echinocactus grusonii ‘Golden Barrel Cactus’

Another sun-loving cactus you might be tempted to add to your indoor collection is Echinocactus grusonii, the Golden Barrel Cactus, sometimes known as the Mother-In-Law Cushion for the long spines that cover the whole of the cactus.

For obvious reasons, you’ll want to keep this plant well out of reach of pets and children! The spines can make it difficult to repot the plant, but you won’t need to do this very often, every couple of years is about right.

When you do repot, use salad tongs or even some cardboard to move the plant and protect your hands from the spines. Only repot one size upward.

It’s perfect as a plant that doesn’t need a lot of attention, as all it requires from you is plenty of direct sunlight and watering as sparingly as every few months in the right conditions.

Keep the soil well-draining, and only water the plant when the soil has dried out. 

Euphorbia trigona ‘African Milk Tree’

While technically a succulent rather than a cactus species, this plant is still striking and deserves a place on this list.

As it is a Euphorbia, it does contain a toxic, white sap that’s quite dangerous as an irritant, as well as when it is ingested, so consider choosing a different plant if you have pets or children, or put the plant in a room they cannot get to.

This is a striking plant, featuring triangular stems and teardrop-like leaves at the ends, but you should be careful, as each one has thorns underneath!

At maturity, it can reach between 2 and 9 feet tall, depending on the growing conditions, but it’s likely to be less than 5 feet tall when grown indoors.

It is a fast-growing plant, so this is something else to keep in mind! 

This plant appreciates a bright and sunny windowsill, preferably a Southern-facing one where it can get as much direct sunlight as possible. Like many cacti species, this succulent likes to dry out completely in between watering.

Water it deeply when the soil does dry out, but don’t leave it sitting in water, as this is a shortcut to killing the plant, as this species has not adapted to soil that stays wet for long periods.

Gymnocalycium mihanovichii ‘Moon Cactus’

The Moon Cactus is an interesting plant, not just for the brightly colored, planet-shaped growth at the top of the stem, but also because it is technically two separate species grafted together.

The top part can come in many colors, such as red, orange, yellow, and pink. 

The care for this particular plant can be a little tricky, as the grafted stem requires different light to the ‘scion’, the top part of the cactus. Keep it in bright and indirect light, somewhere warm that doesn’t get any drafts or near sources of heat.

Let the soil fully dry out in between watering, and use a good-quality succulent or cactus compost mix, with some grit added to improve drainage.

It’s worth knowing that the stem and the scion grow at different rates, and it will eventually change shape, and you’ll need to re-graft it or buy a new one.

Huernia zebrina ‘Lifesaver Cactus’

Technically a succulent rather than a cactus, Huernia zebrina is a striking plant that produces one of the strangest flowers you’ll ever see, with a donut-like shape and tiger-like markings (see also How To Grow Huernia Zebrina).

The flower isn’t for the faint of heart, however, as it is designed to attract flies, and produces a horrible scent that’s designed to mimic rotting flesh!

Some that are put off by the smell and still want to grow this great plant put a clear plastic bag over the flower, that way they can enjoy the plant’s bloom without having to worry about the smell. Ugh. 

Bright and indirect light works best for this plant, but if you want it to bloom, you’ll need to give it morning or late afternoon direct sunlight.

It requires steady temperatures between 50°F and 80°F, and a good-quality cactus compost that’s been amended with some pumice. 

Allow the top two inches of compost to dry out between watering, or even the top half or most of the compost to dry out, but don’t let the plant dry out for too long.

Mammillaria plumosa ‘Feather Cactus’

One of the sweetest, most adorable cacti species you can grow in your home is the Feather Cactus, known botanically as Mammillaria plumosa. 

Don’t be fooled by its cute, fluffy appearance, with white hairs that cover the ball-shaped cactus. While they look like soft down, spines lie beneath, just ready to sink into your skin!

This plant loves lots of light, but it will appreciate some shade in the afternoon when the sun is particularly strong.

When watering, try to keep splashing the plant at an absolute minimum. It’s better to slow the water flow to a trickle rather than watering the plant quickly and splashing it, as this can damage the plant.

Don’t forget to water the plant deeply, however, and allow most if not all the compost to dry out in between watering.

Myrtillocactus geometrizans f. cristatus ‘Dinosaur Back Plant’

Another fascinating cactus you can grow in your home is the Dinosaur Back Plant, which features crested growth that takes the shape of clouds of smoke frozen in time.

Only water this plant when the soil is completely dry, and don’t water the plant at all during winter.

This plant needs as much direct sunlight as you can give it to keep the growth in its characteristically twisted form.

If you don’t have a windowsill that the sun beats down on, it’s worth investing in a good-quality grow light for this plant, which will give the plant the next best thing.

Feed this plant sparingly, around three times or so during the growing season, and keep the plant in well-draining, succulent-suitable soil.

Pilosocerus pachycladus ‘Blue Columnar Cactus’

Sometimes called the Blue Torch Cactus, this plant is a wonderful addition to any room, with its silvery blue color and column-like appearance.

In its native conditions, it can reach 30 feet tall, but on average it will reach about 6 feet tall indoors, more if given the room to do so.

This is not a low-light plant by any means, so keep it somewhere that will get at least 6 hours of direct sunlight not only to keep the color vivid but also to keep the growth healthy, preventing it from stretching out.

Schlumbergera bridgesii ‘Christmas Cactus’

If you’d prefer an easy-to-grow tropical cactus, you’d be hard-pressed to find one as easy and as beautiful as the Christmas Cactus when it is in bloom (see also How To Encourage Flowers On A Christmas Cactus).

These plants are also very long-lived, sometimes known as heirloom plants as families often inherit them!

For this plant to bloom between mid-November and January, in time for the holiday season, it needs full darkness at night, and that means no indoor lights. You can achieve this easily by putting a box over it at night to block out any lights.

It also helps that you can propagate this plant readily by taking stem cuttings.

While you might think it likes dry conditions, this is a tropical cactus, so keep the top inch of the compost damp at all times, but try not to keep the soil wet.

Bright and indirect light will do for most of the day, but full morning sunlight will give this plant a boost. During fall and winter, keep it in direct sunlight to give the plant as much energy as possible.

Selenicereus anthonyanus ‘Ric Rac Cactus’

This beautiful trailing plant, also known as the Fishbone Cactus, is a tropical cactus that loves a bright and indirect position and will appreciate some water when the top two inches of compost have dried out.

Unlike desert cacti, this one likes some humidity, so if you have a bright and indirect bathroom, you’ll see lots of growth on this plant!

Other Things To Consider When Growing Cacti Indoors

Direct Sunlight Needs

To know what kind of sunlight your plant needs, it’s important to look at its native conditions. 

If the species is used to the sun beating down on it all day, you’ll need a very sunny windowsill, but if your cactus is used to a shaded rainforest, a bright and indirect spot with some morning or very late afternoon sunlight is better.

How To Get Indoor Cacti To Bloom

When you want an indoor cactus to bloom, it’s important to know that not all species will flower indoors, especially if they don’t get some direct sunlight.

But some species absolutely will, though they may take a long time to get there. Some cacti species need years to mature before they can flower, but the wait is always worth it.

Provide your plant with the right amount of sunlight for the species, give it the occasional feed, and provide it with enough water and the right temperatures, and this will maximize the chances of your plant blooming.

Can You Summer Indoor Cacti Outside?

It’s a good idea to put your indoor cacti outside for the summer months, but even for the most sun-loving cactus plant, it’s a good idea to gradually introduce them to the outdoors.

Start by putting your houseplant cacti outside for a few hours, in partial shade, and then bring them in. 

Gradually increase the amount of time they are out for, as well as light levels, and within about two weeks, your plants will be hardened off, ready for enjoying the summer outdoors.

Put your plants in a sheltered position, and take them back inside before the frosts come. If there is any heavy rainfall, make sure to tip any that collects on the plant itself, as you don’t want it to rot.

Final Thoughts

Indoor cacti are absolutely beautiful and can withstand some neglect. Just make sure that you get the right type that suits your space, whether that’s a tropical or desert cactus, and the care will be much easier.

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