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 a few times since they have adapted to the extreme conditions of deserts. Cacti store reserves of juices or liquids in their tissues in order to cope with drier periods. Although cacti are simple to care for, there are a few important points to keep in mind in order to provide them with a favorable environment for their development.

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 as far back as the 14th century. Cacti appear in drawings and sculptures of ancient civilizations around the world, such as the Aztecs in Mexico as well as the Moche in Peru.

The nomenclature of Cactaceae has fluctuated greatly throughout history. Indeed, the different species that we know today did not exist in Europe during Antiquity and arrived in progressive waves starting with 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, we continue to find and discover new species or varieties every year!

Natural environment

With more than 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 species of cacti live in humid tropical or subtropical zones, most live in desert regions and have adapted to them using unique characteristics that allow them to conserve water and survive the intense sun of these regions. .

Maintaining your cacti properly: maintenance & advice

Who hasn't heard someone say that cacti don't need water and are great plants for beginners? You may be surprised to learn that this is partly false and that one of the most important factors for a healthy collection is proper watering. Although it is true that cacti do not require a lot of water and can easily tolerate an oversight or two, it is still important to know the needs of different types of cacti in order to provide them with an environment favorable 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 soil is dry, about once a week. This can vary depending on the environment and the species of cactus, so the most important thing is to make sure you let the soil dry 100% before watering again!

During winter, as light diminishes 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 is generally from October to March.

Watering Tropical Cacti vs Desert Cacti

There are several types of cacti that come from different places around the world. There are several species that come from tropical environments as well as other species that come from desert environments. Provenance 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. It is therefore essential to know 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 consists of soaking the potted plants (with holes) in a basin of water. It is important to ensure that the plant is not in direct contact with water. Remove the pot from the basin as soon as the soil on the surface becomes damp and let the plant drain. Make sure not to leave the plant in water for too long to avoid the risk of root rot.

Benefits

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

Disadvantages

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

Top watering method

Top watering is a more familiar method but still requires special attention. When watering your plant, be sure to wait for the water to drip out the bottom of your holey pot. If your pot does not have a hole, it would be beneficial for you to consider transplanting your plants into pots with holes to prevent possible problems.

Deposit : It is important not to put water directly on the cactus as this risks staining or rotting the plant if air circulation is not adequate.

Benefits

Faster watering;
Allows excess salt to be evacuated;
Offers 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 all of the roots to be well watered;
Requires good ventilation.

Choosing the best soil for growing cacti

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

Soil for Desert Cacti

A good desert cactus potting soil starts with a base of 30% high porosity potting soil. We then add approximately 50% pumice and 20% perlite to improve drainage. It is also possible to start with 40% potting soil and 60% pumice and perlite depending on your preferences.

Soil for epiphytic cacti

Epiphytic cactus soil also starts with a base of 30% high porosity soil. We then add approximately 50% pumice and 20%bark to create a soil offering excellent drainage with more organic matter.

Potting: how to transplant a cactus?

The majority of cacti are sold in soil that is not suitable. For repotting, it is best to choose a terracotta pot of the same size or wider than it is high (see the next section to learn how to choose the right pot).

Here are the steps for successful potting:

Make sure the chosen pot 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. There is no need to add a drainage layer except when dealing with a large cactus or to add weight to your pot;
Remove the cactus using a folded newspaper or a pair of triple-layer gloves to avoid getting pricked and to be able to position it securely in the middle of the pot. It is also possible to wrap it in fabric, leaving excess to create a handle;
Fill the remaining space around the rootball 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 consideration when purchasing your plant as it influences its growth. The ideal is to buy 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 it will be necessary to base it on the following two elements:

The diameter of the pot

Cacti and a large majority of succulents do not need a large space in width to grow and be healthy. This criterion is therefore not a priority. Still manage to keep a space of one inch around the base of the cactus so that it can develop well.

The depth of the pot

You should always find out about the depth of the roots before choosing a cactus pot. You will need to provide a few centimeters of additional soil below the roots in order to aerate the plant. If the only pot available is too deep, it is possible to add gravel to the bottom of the pot to reduce the quantity of potting soil and increase the speed at which the potting soil can dry.

The drainage hole: a super important detail

The ideal is to always use a pot with an irrigation hole. If you still want to plant in a ceramic pot cover without a hole (more beautiful, but more risky for the health of your plants), you can drill one with a drill bit provided for this purpose. Make sure you always have water flowing while drilling to avoid breaking your pot cover due to friction. You can also make an even more draining mixture to ensure that the excess water drains away more quickly; on the other hand you will have to water more often.

Flowering and fertilization of cacti

Cacti are generally recognized for their thorns and varied shapes, but did you know that the majority of cacti also produce surprising flowers in a wide variety of colors? Most cacti flower following a period of dormancy, which is necessary for these plants to flourish.

To start flowering and allow your cactus to flower, 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 start 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 that it is important to apply fertilizer more frequently.

There are several species of cactus with diurnal (day) flowering and nocturnal (night) flowering. Make sure you know the types of cacti in your collection to provide them with the right environment.

Hardiness: is it possible to keep cacti outside all year round?

In general, cacti are extremely heat tolerant because they come from desert regions around the world. However, in these areas, temperatures can also drop very low at night, and particularly in winter when it can even snow. Certain species, depending on their origins and with the right protection, can therefore naturally resist very cold, sometimes freezing, temperatures.

When cacti are dormant, their metabolism goes down to allow them to survive during colder periods, while waiting for their growth period. It is for this reason that most species should hardly 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)
Opuntia polyacantha (-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

In order to allow the plant to modify the chemical substances contained in the soil into assimilable nutrients, it is essential to provide adequate light to your cacti during their growth period (generally from March to October). If a cactus does not receive good light, it will begin to grow in an etiolated manner. His life expectancy will then be reduced and he will unfortunately end up dying of starvation.

Several factors can cause the light available to your cacti to not be intense enough to provide them with optimal development. Remember that depending on the type of window and the orientation of your house, there are much fewer rays passing through than you might think. This is often common in new construction which uses triple thickness windows, with gas and anti UV film. In these cases, we always recommend adding an artificial lighting lamp .

Some cactus species require less lighting than others. It is therefore important to know the types of cacti in your collection so that you can adapt the lighting according to their needs.

Full sun (direct light)

The majority of desert cacti tolerate long periods of full sun without difficulty. Place them on your sunny south-facing window sill, in a greenhouse, or under artificial LED light . It is important to always properly acclimatize the plants if you plan to take them outside during the summer to avoid burns that could occur.

Partial shade (subdued or indirect light)

There are also several species that grow under the shelter of bushes and small shrubs in arid areas. These plants generally appreciate light shade and require shelter from mid-day sun. Among these species, we find several epiphytic cacti.

Example: Epiphyllum

Shadow

There are some species that tolerate shade, but in the short term. On the other hand, we often notice that these plants eventually begin to grow in pride (etiolation).

Adapting to the dormant period

Contrary to popular belief, cacti need a dormant period. We recommend overwintering your cacti in a room where the light is subdued, with a constant temperature between 5-10 degrees and low humidity. It is desirable to have minimal light during this period because even though the plants do not feed or drink during their rest, they continue to do the minimum photosynthesis for their survival. Thanks to this process, your cacti will be stronger and more vigorous, will give you magnificent flowers in due time and will also have a longer lifespan.

Warning : You should always research the cycle of each cactus because their dormant period and their need for light can differ from one species to another.

Edibility and fruits of cacti

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

Pitaya (Dragon Fruit)

Dragon Fruit, also known by the Spanish name pitaya or pitahaya, is the fruit of the Selenicereus undatus plant . 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, low-care appearance. Its fruit is sweet and slightly acidic, reminiscent of the taste of apricot. It also offers a nice crunchy texture and excellent nutritional value.

The organ cactus (Organ Pipe Cactus)

The 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 mild flavor with a succulent texture.

The prickly pear cactus (Prickly Pear 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, sweet flavor.

The saguaro cactus

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

What are poisonous cacti?

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

Here are 3 types of cacti that are not edible:

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

Our favorite cactus species

Cereus forbesii "Spiralis"

Cereus forbesii "Spiralis", is a candle cactus that was named after its unique and distinctive shape, causing it to rotate on itself as it grows so as to form a "spiral". When flowering, this large cactus develops large, showy flowers, making it a welcome addition to any plant collection.

Cereus Forbesii "Spiralis"