Charlie Albone: Garden expert gives lay of the land when it comes to growing and understanding cacti

Growing cacti is a rewarding and relatively easy way to get into gardening.

They are tough, sun tolerant, require little additional watering and are generally very low maintenance due to slow growth.

The issue, due to that growth rate, is that they are expensive! Propagating cacti, however, couldn’t be easier.

Before you start it’s important to understand the difference between cacti and succulents.

Most cacti are succulents, but not all succulents are cacti. Confused? Cacti are identified by their spines — they have fleshy stems that store water and photosynthesise, whereas succulent plants store water and nutrients in their leaves.

You can propagate succulents in many ways, including leaf cuttings, division, seed and layering.

With cacti you can grow from seed, although you are in for the long haul and the moisture-rich stem makes cuttings a touch more complicated.

Plants you may know are the Mexican (tent-pole style) cactus, silver torch and prickly pear. There is also a common spineless prickly pear that is very popular with landscapers. Obviously, it’s easier to plant!

First, you need to take a cutting of your cacti and you need a very sharp knife for this. Clean it with rubbing alcohol to prevent any diseases from getting into your plant. Locate a good spot to cut your cacti.

For plants like the prickly pear, cut below where the stem swells. These plants look like paddles stacked on top of one another so just remove a single paddle.

With single-stem or multi-stem cactus, you want a healthy leader in an inconspicuous place in your garden, as taking a cutting will leave the rest of the plant looking unsightly.

When propagating any plant, you want to cut just below a node as this is where the roots will form. Cacti have a unique feature called areoles, where the nodes are packed very closely together without internodes separating them. This means you just pick the height you want and cut away, trying to get the cut parallel to the ground or with only a slight angle.

If you can acquire powdered sulphur, this will speed up the healing process. It can be applied to both the plant and the cut end of the cutting — but it’s not essential. What is essential is leaving your cutting to dry out in a cool shaded part of the garden. (Be warned: if you plant up a fresh cutting, it will simply rot away.)

You will notice a callus forming on the base and you may even see some root growth after a couple of weeks. When the callus is formed, pot up the cutting into a very free-draining mix — even coarse sand or river pebbles will do — but try and put the cutting into the smallest pot possible.

The small pot will heat up, stress the plant and actually promote strong root growth. When you see roots coming out of the bottom of the pot you can pot it up into something larger and more suitable for long-term growth.

The trick when potting up into a bigger pot is to have a layer of nutrient-rich compost/heavy potting mix in the bottom third of the pot, then a layer of poor quality, free-draining soil on top, and then use this same poor mix to backfill the cutting.

This layering will make the roots search for good quality soil and nutrients.

When the roots do hit it, the plant will know to send out plenty of roots to this area of the plant. The more roots a plant has under the ground, the better the growth above the ground.

If your cacti is outside there should be no reason to water it. Let mother nature take care of it.

The issues you will have will come from too much water. Your cuttings are the same — too much water will lead to rapid growth that will be weak and susceptible to failure.

So, unlike most things in the garden, just leave it alone!