Cactus care

Mar 04, 2022Jean-Michel Tremblay

Cacti are definitely unique, and it's no secret that this family of plants is all the rage among collectors and plant lovers around the world with their varied shapes and surprising colors. These plants are ideal for people who tend to forget to water them, as they have adapted to the extreme conditions of deserts. Cacti store reserves of sap or liquid 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 a favorable environment for their growth.

History & origins
Natural environment
Maintenance & advice
Watering
Potting soil
Potting
Pot size
Bloom
Hardiness
Lighting
Edibility
Toxicity
Species

History & origins

There are several references to cacti dating back to the 14th century. Cacti appear in the drawings and sculptures of ancient civilizations around the world, such as the Aztecs in Mexico and the Moche in Peru.

The nomenclature of Cactaceae has fluctuated greatly throughout history. Indeed, the various species we know today did not exist in Europe during Antiquity and arrived in progressive waves following the "discovery" of America.

Interest in cacti during the 20th century led to excessive collecting and poaching, which caused some species to disappear completely from the wild. Fortunately, new species and varieties continue to be discovered and found every year!

Natural environment

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

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

Although a few cactus species inhabit humid tropical or subtropical areas, 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 regions.

How to properly care for your cacti: maintenance & advice

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 false and that one of the most important factors for a healthy collection is proper watering. While it's true that cacti don't require a lot of water and can easily tolerate a watering oversight or two, it's still important to understand the needs of different types of cacti in order to provide them with a favorable environment for growth.

How often should you water cacti?

During the growing season, generally from April to late September, we recommend watering your cacti only when the soil 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 you let the soil dry out 100% before watering again!

During the winter, as light decreases and temperatures drop, cacti often enter a dormant period. If your plant is in a cool room between 7 and 14 degrees, it is recommended to never water it (or almost never) during this period, which generally occurs from October to March.

Watering Tropical Cacti vs. Desert Cacti

There are several types of cacti that come from different locations around the world. There are several species that come from tropical environments as well as others that come from desert environments. Origin is a factor that has a real impact on the watering needs of individual plants. Generally speaking, desert cacti require less frequent watering than tropical cacti, which require more regular watering. Therefore, it is essential to understand the needs of the cacti in your collection in order to provide them with adequate watering.

Different Watering Methods for Cacti

Drenching method

This method involves soaking potted plants (with holes) in a basin of water. It is important to ensure that the plant does not come into direct contact with the water. Remove the pot from the basin as soon as the surface soil becomes damp and allow the plant to drain. Make sure not to leave the plant in the water for too long to avoid the risk of root rot.

Benefits

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

Disadvantages

Does not leach excess mineral salts into the soil;
Takes longer to water;
Requires more handling.

Top watering method

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

Caution : It is important not to put water directly on the cactus as this may stain or rot the plant if there is insufficient air circulation.

Benefits

Faster watering;
Allows excess salt to be removed;
Provides better fertilization.

Disadvantages

Possibility of overwatering the plant and increasing the risk of rot if the water remains in contact with the cactus for too long;
Does not allow all the roots to be watered well;
Requires good ventilation.

Choosing the best soil for cactus growth

Depending on the type and species of cactus, soil needs can vary. Generally speaking, a regular cactus mix can be as effective as a homemade one. If you want to provide an environment suited to a specific type of cactus, we recommend mixing your own soil to customize it to your needs.

Potting soil for desert cacti

A good desert cactus soil mix starts with a base of 30% high-porosity potting soil. Then, approximately 50% pumice and 20% perlite are added to improve drainage. Alternatively, you can start with 40% potting soil and 60% pumice and perlite, depending on your preference.

Potting soil for epiphytic cacti

Epiphytic cactus soil also starts with a base of 30% high-porosity potting soil. About 50% pumice and 20% bark are then added to create a soil with excellent drainage and more organic matter.

Potting: How to transplant a cactus?

Most cacti are sold in unsuitable potting soil. When repotting, it's best to choose a terracotta pot that's the same size or wider than it is tall (see the next section for how to choose the right pot).

Here are the steps for successful potting:

Make sure the pot you choose has a drainage hole;
Lightly moisten your potting soil before use to avoid volatile particles in the air;
Place a little potting soil 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 a folded newspaper or a pair of triple-layered gloves to avoid pricking yourself and to be able to position it properly in the center of the pot. It is also possible to wrap it in fabric, leaving some excess to create a handle;
Fill the remaining space around the root ball with potting soil and compact lightly;
Wait about 7 days before watering your cactus with room temperature water. This allows the roots to heal and prevent rot.

Choosing the right pot size

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

The diameter of the pot

Cacti and most succulents don't need a lot of space to grow and thrive, so this isn't a priority. However, try to keep an inch of space around the base of the cactus so it can thrive.

The depth of the pot

Always check the root depth before choosing a cactus pot. You'll need to add a few inches of extra soil beneath 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 soil and increase the speed at which the soil dries out.

The drainage hole: a super important detail

Ideally, you should always use a pot with an irrigation hole. If you still want to plant in a ceramic pot without a hole (more beautiful, but riskier for the health of your plants), you can drill one with a drill bit designed for this purpose. Make sure there is always water flowing while drilling to avoid breaking your pot by friction. You can also make an even more draining mix to ensure that excess water drains faster; however, you will have to water more often.

Flowering and fertilizing cacti

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

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 signals to the plant that it is time to reproduce. At this time of year, we also notice an acceleration in the growth of cacti, which means it is important to apply fertilizer more frequently.

There are several cactus species that bloom during the day and at night. Make sure you understand the types of cacti in your collection so you can provide them with the right environment.

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

In general, cacti are extremely heat-resistant because they originate from desert regions around the world. However, in these areas, temperatures can also drop very low at night, especially in winter, when it can even snow. Some species, depending on their origins and with the right 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 while they wait for their growing season. For this reason, most species hardly need to be watered during this season.

List of cactus species tolerant 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 the ideal type of lighting for your cacti

To allow the plant to convert the chemicals in the soil into available nutrients, it is essential to provide your cacti with adequate light during their growing season (usually from March to October). If a cactus does not receive adequate light, it will begin to grow lean. Its lifespan will then be reduced, and it will unfortunately die of starvation.

There are several factors that can cause the light available to your cacti to not be intense enough for optimal growth. Keep in mind that depending on the type of window and the orientation of your home, there are far fewer rays passing through than you might think. This is often common in new constructions that use triple-layered windows, with gas and anti-UV film. In these cases, we always recommend adding an artificial lighting lamp .

Some cactus species require less light than others, so it's important to understand the types of cacti in your collection so you can adjust the lighting to suit their needs.

Full sun (direct light)

Most desert cacti can easily tolerate long periods of full sun. Place them on a sunny south-facing windowsill, in a greenhouse, or under LED artificial lighting . It's important to always acclimate plants properly if you plan to move them outside during the summer to avoid sunburn.

Partial shade (dim or indirect light)

There are also several species that grow sheltered by bushes and small shrubs in arid areas. These plants generally enjoy light shade and require shelter from the midday sun. These species include several epiphytic cacti.

Example: Epiphyllum

Shadow

There are some species that tolerate shade, but only for a short time. However, it is often noticed that these plants eventually begin to grow leggy (etiolation).

Adapting to the dormant period

Contrary to popular belief, cacti need a dormant period. We recommend overwintering your cacti in a room with dim light, a constant temperature between 5-10 degrees 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 necessary for their survival. Thanks to this process, your cacti will be stronger and more vigorous, will give you a magnificent bloom when the time comes and will also have a longer lifespan.

Caution : Always research the cycle of each cactus as their dormancy period and light requirements may differ from species to species.

Edibility and fruits of cacti

There are several species of cactus 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 of pitaya or pitahaya, is the fruit of the Selenicereus undatus . This exotic fruit has a tropical flavor reminiscent of watermelon. In addition, its high fiber content makes it a suitable dietary food and provides you with 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 tart, reminiscent of apricots. It also offers a lovely crunchy texture and excellent nutritional value.

The Organ Pipe Cactus

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

The prickly pear cactus (Prickly Pear Cactus)

Prickly pears are the fruit of the Opuntia ficus-indica cactus, a native Mexican plant. When raw and green, prickly pears have a tropical flavor. Once they ripen and turn reddish-orange, they have a mild, sweet flavor.

The saguaro cactus

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

Which cacti are poisonous?

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

Here are 3 types of cactus that are not edible:

The peyote cactus (pronounced "peyote") contains several alkaloids, including mescaline;
The San Pedro cactus contains a large number of alkaloids, including mescaline;
The Bolivian torch cactus is poisonous and contains several alkaloids that can cause a psychedelic effect.

Our favorite cactus species

Cereus forbesii "Spiralis"

Cereus forbesii 'Spiralis' is a candle cactus named after its unique and distinctive shape, which causes it to twist as it grows, forming a 'spiral'. When it blooms, this large cactus develops large, showy flowers, making it a welcome addition to any plant collection.

Cereus Forbesii "Spiralis"