Growing Cactus and Succulents (C and S)

The cultivation tips given below are general and suit most C and S, but there are some plants that require different or more specialised care.

There is plenty of more information at branch meetings!

For raising plants from seed see this page.

For cultivation of Lithops see this page.
For cultivation of Pachypodiums and Caudiciforms see this page.

For cultivation of all sorts of cacti and succulents

Jump to:
Potting Mix ... Container ... Pests & Disease ... Fertiliser ... Lighting ... Temperature ... Repotting ... Flowering ... Propagation

Watering

C and S require water!
Often the first question a new C and S grower asks is "When do I water it?".
The plant is already potted up (hopefully!), so the first pressing issue is watering.
There is no easy rule and the answer depends on the plant, the season, the potting mix, the size of the pot it is in, the location and many other factors - but don't let that intimidate you.
As a general rule C and S should be watered once the potting mix dries out from the previous watering, during the plant's growing season (which can be summer (more likely) or winter (some C and S)).
How long the mix takes to dry out from the previous watering depends on any number of factors as mentioned above, it may mean watering 3 times a week in summer, or not for weeks in mid-winter.
How do you know when the mix is dry from the last watering? - "knowledge", a water meter, judging by the weight of the pot, a little dig into the mix (careful not to disturb roots) are all used by growers.
Extreme desert plants (from certain areas in Africa or America) require less water, epiphytic/forest cacti require more water.
When you do water, water well so that water runs out the bottom of the pot, and the mix is saturated. Pick a warm sunny day to water so the mix doesn't stay wet too long, some growers recommend only watering in the early morning, but I have watered in the evening in summer if I know the next day is fine and sunny. If watering in the sun ensure no little droplets of water are left on the plant to perhaps burn the plant.

Potting Mix

C and S do NOT grow in sand!
The potting mix must be free draining, any water that remains in the mix long-term will eventually cause the plant to rot and collapse. This is achieved by adding pumice or stone grit (not sand) to a normal peat, bark or compost based potting mix. The ratio of grit to potting mix depends on the plant and it's natural habitat i.e. extreme desert, grasslands or forest dwelling, pumice/stone grit can make up one-third to two thirds of the mix.
Peat can be very hard to rewet once it dries out and subsequent watering may mean the water runs down the side of the pot and the plant's roots stay dry. Rewetting agents from garden centres or a detergent (e.g. Teepol)can be used.

Container or pot

C and S can grow in just about any container - as long as it has drainage.
The container must have a drainage hole in it so that surplus water can drain away from the pot, otherwise just about any container can be used to grow C and S as long as the size of the plant is appropriate to the size of the pot. The pot can be plastic, terracotta clay (un/glazed), ceramic, even a fry-pan - as long as it has (a) drainage hole/s in it.
Putting a layer of larger stones in the bottom of a pot can actually DECREASE drainage as it interferes with water transport, so either a flat stone over the hole, some fine mesh or nothing (as long as mix doesn't fall out bottom) is fine.
Some plants prefer shallow pots where the roots can spread out, while others like a deep pot as they have a large tap root. Clay pots are a bit more forgiving with over-watering as water can escape through the unglazed sides as well as the bottom.
Putting a small plant in a large container may lead to long periods of wet soil mix and hence fungal diseases.

Pesticides and diseases

Hopefully your new plant won't have any pests or diseases when you first get it, but eventually you may come across a mealy bug or twenty!
Mealy bug is the most common insect to attack C and S, it can live on the plant or on the roots in the soil (sight unseen), the above ground bug is distinguished by a cotton-wool type covering with a slater like insect underneath. The cotton-wool can repel any insecticide sprayed onto it, so often a wetting agent in the insecticide spray is required. There are 2 types of insecticide: Contact - works by being in direct contact with the insect; and Systemic - which is taken up by the plant roots into it's "sap" where-upon the insect sucks the sap and takes in the poison.
It is a good idea to rotate with different insecticides so that the insects don't build up a resistance to any one insecticide. Ask your local garden centre.
Always use the correct strength (weaker strengths will lead to resistance building up) and take care of yourself as they are poisons.

Scale is an insect that sticks to the plant with a hard outer casing and can be quite resistant to insecticides, it can be picked off with a sharp knife - but it may leave a mark on the plant.
Red Spider Mite can cause quite considerable damage to a plant leaving the plant skin brown and disfigured and is a symptom of the dry conditions that the plants are grown in, so simply spraying a water mist on the plant can keep them at bay, otherwise a special miticide insecticide is required.

Fungus/rot can quickly reduce a prized plant to "mush", hopefully you will see the signs before and cut out the affected area and save the rest of the plant - abet disfigured. It can be due to a cut or puncture that has allowed the fungus in, a weakened or forced plant, or too much watering.
Cut out the affected part until you get to clean healthy tissue (sterlising the knife before the last cut into the healthy tissue) then dusting with a fungicide like Sulphur and then keep the plant in a dry, well ventilated area - hoping for the best!
Another approach if suitable is to cut the plant well above the rot and treat as a cutting (see below), firstly check there is no rot (redness) in the vascular bundle of the cutting, cutting further up until the vascular bundle is "clean", once again ensuring the knife is sterilised for the last cut. Throw away the rest of the plant with rot in it.

For a websites dedicated to cacti pests see Cactus Clinic or Cactus Mall pest page.

Fertiliser

As a rule C and S don't require much fertiliser, except certain species (Orchid or Epiphytic cactus) or those overdue for a repot. The Fertiliser must not be high in Nitrogen, otherwise the plant will be "forced" and grow out of character or more seriously be prone to disease or rot and less likely to flower in some species. Cacti will have less pronounced spines.
A half to quarter strength Tomato fertiliser is usually a good one to use in the growing season.
pH can a big part in availability of nutrients to the plant.

Lighting

Your plants will let you know if they are getting too little or too much (yes they can get too much!), too little light will lead to the growing point becoming elongated/smaller in diameter and spindly as well as paler in colour.
Too much sunlight can lead to a reddening of the plant and stopping of growth or even scorching (browning) of the exposed area.
The plant should be grown in as much light as possible (without scorching) to get the best growth results with a nice compact plant with good spination (cactus) and full flowering potential.
If moving a plant from a previously shadier area to a sunnier area, acclimitise the plant over a couple of days so it doesn't get sun burnt.

Temperature

In their natural habitat many plants experience freezing (even covered in snow) temperatures BUT usually only during their dry season. So (for summer growers) in summer temperatures can be high, as long as there is plenty of ventilation, and in winter temperatures can descend below freezing AS LONG AS THE PLANT IS COMPLETELY DRY.
Some other plants (e.g. from Caribbean or tropics) need a minimum temperature of 5 - 10 degrees Celsius in winter to survive and suffer if the temperature falls below this.

Repotting

Depending on your time, inclination and the size of the plant, repotting your plant is a yearly to 2 yearly job.
When the plant is too big for it's pot it can be potted onto it's next size pot often with minimum root disturbance, alternatively if just fresh mix is required the old soil can be shaken from the roots and new mix added in the same sized pot if the plant is not too big.
Check for any root mealy bugs.
After repotting watering should be with-held for a while (1 to 3 weeks) to allow broken roots to heal and lessen the chance of fungal attack.

Flowering

Despite rumors to the contrary C and S, once they reach maturity, do flower regularly every year (given the right treatment), except for a few that flower once and then die (hopefully leaving behind some pups). Maturity may be 2 years from seed as is the case for Rebutias, or 30-80 years for some Agaves or the huge columnar cactus in Arizona etc.

Propagation

The easiest way to get extra plants is to take cuttings (where possible), this in easiest in plants that offset or pup, where the pup can usually be twisted slightly to separate from the mother. Otherwise a sharp clean knife can be used to separate a piece of plant (but maybe disfiguring the mother plant). Most leaf succulents can simply have the leaves picked, calloused and then laid on a sandy mix. Some offsets or leaves even develop roots while still attached to the mother plant.
Cuttings are best taken in the growing season, allowing the cut to dry or callous (maybe a week or two depending on the size of the open wound), and then put on the surface of a very gritty mix or even just stone grit. Watering should be only enough to keep the soil/grit slightly moist until roots have formed and the plant can be potted up normally.

Seed-raising is the best way to get a large number of plants cheaply, but it does require patience and some species are definitely easier than others! The society has a seedbank where members and the public can purchase seeds.

Grafting is another means of propagation where the vascular bundle of a stock plant (strong and healthy) is matched with the vascular bundle of a scion (a very small seedling, a chlorophyll lacking plant, a crest, a very small cutting (e.g. left-over from a diseased plant)) allowing transfer of water and nutrients from stock to scion.
There are books in the library that give detailed illustrated instructions on how to graft.

I hope you enjoy your plant/s - and we will see you at one of our branch meetings!