Cactus care

Mar 04, 2022Jean-Michel Tremblay

Cacti are definitely unique, and it’s no secret that this family of plants is a hit with collectors and plant lovers worldwide, thanks to their varied shapes and surprising colors. These plants are ideal for people who tend to forget a few waterings, as they have adapted to the extreme conditions of deserts. Cacti store reserves of sap or liquids in their tissues to cope with drier periods. Although cacti are simple to care for, there are a few important points to keep in mind to provide them with an environment conducive to their development.

History & Origins
Natural Environment
Care & Tips
Watering
Potting Mix
Repotting
Pot Size
Flowering
Hardiness
Lighting
Edibility
Toxicity
Species

History & Origins

Several references to cacti date back as far as the 14th century. Cacti appear in drawings and sculptures of ancient civilizations across the world, such as the Aztecs in Mexico and the Moche in Peru.

The nomenclature of Cactaceae has been very fluid throughout history. Indeed, the different species we know today did not exist in Europe during antiquity and arrived in progressive waves starting from the "discovery" of America.

The interest in cacti during the 20th century led to excessive collection and poaching, which caused the complete disappearance of some species in the wild. Fortunately, new species or varieties continue to be found and discovered every year!

Natural Environment

With over 2,000 species across nearly 139 different genera, cacti are native to North and South America, ranging from British Columbia and Alberta to Chile and Argentina.

Mexico boasts the largest number and variety of cactus species worldwide. The only cacti native to the Old World are members of the genus Rhipsalis, found, among other places, in East Africa, Madagascar, and Sri Lanka.

Although some cactus species inhabit humid tropical or subtropical zones, most live in desert regions and have adapted to them with unique characteristics that allow them to conserve water and survive the intense sun of these areas.

Proper Cactus Care: Maintenance & Tips

Who hasn't heard someone say that cacti don't need water and are excellent plants for beginners? You might be surprised to learn that this is partly untrue and that one of the most important factors for a healthy collection is adequate watering. While it's true that cacti don't require much water and can easily tolerate an oversight or two, it's still important to understand the needs of different types of cacti to provide them with an environment conducive to their growth.

How often should cacti be watered?

During the growing season, generally from April to the end of September, we recommend watering your cacti only when the potting mix is dry, about once a week. This can vary depending on the environment and cactus species, so the most important thing is to make sure the potting mix dries out 100% before watering again!

During winter, as light decreases and temperature drops, cacti often enter a dormancy period. If your plant is in a cool room between 7 and 14 degrees Celsius, it is recommended to almost never water it during this period, which usually runs from October to March.

Watering tropical cacti vs. desert cacti

There are several types of cacti that come from different places around the world. These include many species from tropical environments as well as other species from desert environments. Origin is a factor that has a real impact on the watering needs of individual plants. Generally, desert cacti require less frequent watering than tropical cacti, which require more regular watering. It is therefore essential to understand the needs of the cacti in your collection to provide them with adequate watering.

Different watering methods for cacti

Bottom watering method

This method involves soaking potted plants (with drainage holes) in a basin of water. It's important to ensure the plant is not in direct contact with the water. Remove the pot from the basin as soon as the topsoil becomes damp and allow the plant to drain. Be sure not to leave the plant in water for too long to avoid the risk of root rot.

Advantages

Complete rehydration of the potting mix;
Creation of channels for water passage;
Allows the plant to drink what it truly needs;
Better root system development;
Prevents rot in the center of the plant that could be caused by water accumulation (for example: when watering a cluster-growing cactus like a sulcorebutia.)

Disadvantages

Does not remove excess mineral salts from the potting mix;
Takes more time for watering;
Requires more handling.

Top watering method

Top watering is a more familiar method but still requires careful attention. When watering your plant, make sure to wait until water drains from the bottom of your pot's drainage hole. If your pot doesn't have a hole, it would be beneficial for you to consider transplanting your plants into pots with holes to prevent potential problems.

Warning: It is important not to put water directly on the cactus, at the risk of staining or causing the plant to rot if air circulation is not adequate.

Advantages

Faster watering;
Helps to flush out excess salt;
Provides better fertilization.

Disadvantages

Possibility of overwatering the plant and increasing the risk of rot if water remains in contact with the cactus for too long;
Does not allow for thorough watering of all roots;
Requires good aeration.

Choosing the best potting mix for cactus development

Depending on the type and species of cactus, potting mix needs can vary. Generally, a regular cactus mix can be as effective as a homemade mix. If you want to provide an adapted environment for a specific type of cactus, we recommend mixing your potting mix yourself to customize it to your needs.

Potting mix for desert cacti

A good desert cactus potting mix starts with a base of 30% high-porosity potting mix. Then, about 50% pumice stone and 20% perlite are added to improve drainage. It is also possible to start with 40% potting mix and 60% pumice stone and perlite, depending on your preferences.

Potting mix for epiphytic cacti

Epiphytic cactus potting mix also starts with a base of 30% high-porosity potting mix. Then, about 50% pumice stone and 20% bark are added to create a potting mix that offers excellent drainage with more organic matter.

Repotting: how to transplant a cactus?

The majority of cacti are sold in unsuitable soil. For repotting, it is preferable to choose an unglazed clay pot of the same size or wider than it is tall (see the next section to learn how to choose the right pot).

Here are the steps for successful repotting:

Ensure the chosen pot has a drainage hole;
Lightly moisten your potting mix before use to avoid airborne particles;
Place some potting mix at the bottom of your pot. It is not necessary to add a drainage layer unless it is a large cactus or to add weight to your pot;
Remove the cactus using folded newspaper or triple-layered gloves to avoid getting pricked and to be able to position it properly in the middle of the pot. It is also possible to wrap it in fabric, leaving extra to create a handle;
Fill the remaining space around the root ball with potting mix and compact lightly;
Wait about 7 days before watering your cactus with room temperature water. This allows the roots to heal and prevents rot.

Choosing the right pot size

Pot size is an important factor to consider when purchasing your plant, as it influences its growth. Ideally, purchase the repotting pot at the same time as the plant to avoid buying a pot of the wrong size. The pot size will therefore depend on the size of the plant, and you should base your decision on the following two elements:

The diameter of the pot

Cacti and a large majority of succulents do not need a lot of width to grow and be healthy. This criterion is therefore not a priority. However, make sure to leave an inch of space around the base of the cactus so that it can develop properly.

The depth of the pot

Always inquire about root depth before choosing a pot for cacti. You'll need to allow a few extra centimeters of soil below the roots to aerate the plant. If the only available pot is too deep, you can add gravel to the bottom of the pot to reduce the amount of potting mix and increase the rate at which the potting mix can dry.

The drainage hole: a super important detail

The ideal is to always use a pot with a drainage hole. If you still want to plant in a ceramic cachepot without a hole (more aesthetically pleasing, but riskier for your plants' health), you can drill one with a drill bit designed for this purpose. Make sure to always have water flowing during drilling to avoid breaking your cachepot due to friction. You can also make an even more draining mix to ensure that excess water drains faster; however, you will need to water more often.

Flowering and fertilization of cacti

Cacti are generally known for their thorns and varied shapes, but did you know that most cacti also produce surprising flowers in a wide variety of colors? Most cacti bloom after a dormancy period, which is necessary for the development of these plants.

To initiate flowering and allow your cactus to bloom, it is therefore necessary to create a "thermal shock" in order to recreate its natural environment. This thermal shock, in nature, often occurs around April and signals the beginning of summer. It is often accompanied by an abundance of light and indicates to the plant that it is time to reproduce. At this time of year, there is also an acceleration in cactus growth, which means it is important to apply fertilizer more frequently.

Several cactus species exhibit diurnal (daytime) and nocturnal (nighttime) flowering. Make sure you know the types of cacti in your collection to provide them with an adequate environment.

Hardiness: Is it possible to keep cacti outdoors year-round?

In general, cacti are extremely resistant to heat because they originate from desert regions around the world. However, in these areas, temperatures can also drop very low at night, and especially in winter when it can even snow. Some species, depending on their origins and with proper protection, can therefore naturally withstand very cold, sometimes freezing temperatures.

When cacti are dormant, their metabolism slows down to allow them to survive during colder periods, awaiting their growth period. This is why most species should be watered almost never during this season.

List of cactus species tolerant of between -20C and -35C (Zone 5a / 5b)

Coryphantha vivipara (or Escobaria vivipara) (-20 °C)
Escobaria missouriensis (-20° C)
Escobaria sneedii (-20 °C)
Escobaria robbinsiorum (-20 °C)
Echinocereus reichenbachii var. baleyi (-23 °C)
Echinocereus triglochidiatus (-25 °C)
Echinocereus viridiflorus (-25 °C)
Echinopsis chamaecereus (also called Chamaecereus silvestrii or Lobivia silvestrii) (-20 °C)
Opuntia cymochila (-25 °C)
Opuntia fragilis (-25 °C)
Opuntia humifusa (-25 to -35 °C)
Pediocactus peeblesianus var. fickeisenii (-25 °C)

*Source: https://www.cactus-encyclo.com/cactus-gel-froid/

Providing ideal lighting for your cacti

To enable the plant to convert chemicals in the soil into usable nutrients, it is essential to provide adequate light for your cacti during their growth period (generally from March to October). If a cactus does not receive good light, it will start to grow etiolated. Its life expectancy will then be reduced, and it will unfortunately eventually die of starvation.

Several factors can cause the light available to your cacti not to be intense enough for optimal development. Don't forget that depending on the type of window and the orientation of your house, much less light passes through than one might think. This is often common in new constructions that use triple-pane windows, with gas and UV-blocking film. In these cases, we always recommend adding artificial lighting.

Some cactus species require less light than others. It is therefore important to know the types of cacti in your collection in order to adapt the lighting to their needs.

Full sun (direct light)

The majority of desert cacti easily tolerate long periods of full sun. Place them on your sunny south-facing windowsill, in a greenhouse, or under an LED artificial light. It is important to always acclimate plants well if you plan to take them outside during the summer to avoid burns that could occur.

Partial shade (filtered or indirect light)

There are also several species that grow sheltered by bushes and small shrubs in arid areas. These plants generally appreciate light shade and need to be protected from midday sun. Among these species are several epiphytic cacti.

Example: Epiphyllum

Shade

Some species tolerate shade, but for a short term. However, it is often observed that these plants eventually begin to etiolate (grow tall and spindly).

Adapting to dormancy

Contrary to what one might believe, cacti need a period of dormancy. We recommend overwintering your cacti in a room with filtered light, at a constant temperature between 5-10 degrees Celsius and low humidity. It is desirable to have a minimum of light during this period because even if the plants do not feed or drink during their rest, they continue to perform the minimum photosynthesis for their survival. Thanks to this process, your cacti will be stronger and more vigorous, will give you magnificent blooms when the time comes, and will also have a longer lifespan.

Warning: You should always research the cycle of each cactus as their dormancy period and light requirements can differ from one species to another.

Edibility and Cactus Fruits

There are several cactus species that are not only edible but are also known for their unique fruits with exotic flavors.

Pitaya (Dragon Fruit)

Dragon Fruit, also known by its Spanish name pitaya or pitahaya, is the fruit of Selenicereus undatus. This exotic fruit has a tropical flavor reminiscent of watermelon. Moreover, its high fiber content makes it a suitable diet food and offers you a large number of vitamins and benefits.

Peruvian Apple Cactus (Peruvian Apple)

Cereus peruvianus, also known as the Peruvian apple cactus, is known for its tall, columnar appearance and low maintenance. Its fruit is sweet and slightly acidic, reminiscent of the taste of apricot. It also offers a beautiful crunchy texture and excellent nutritional value.

Organ Pipe Cactus

Stenocereus thurberi, commonly called organ pipe cactus, is a species native to Mexico and the United States. The fruits of this plant have a sweet flavor with a succulent texture.

Prickly Pear (Barbary Fig Cactus)

Prickly pears are the fruit from Opuntia ficus-indica, a cactus native to Mexico. When raw and green, prickly pears have a tropical taste. Once they ripen and turn orange-red, they have a mild and sweet flavor.

Saguaro Cactus

Saguaro fruit comes from Carnegiea gigantea and has a sweet and subtle taste, which is not as strong as that of prickly pears. Native to Mexico, this cactus is the only species of the monotypic genus Carnegiea.

Which cacti are toxic?

Although some cactus plants are edible, there are several cactus species that are toxic and unfit for consumption.

Here are 3 types of cacti that are not edible:

Peyote cactus contains several alkaloids, including mescaline;
San Pedro cactus contains a large number of alkaloids, including mescaline;
Bolivian torch cactus is toxic and contains several alkaloids that can cause a psychedelic effect.