Brunnings Cactus and Succulent Mix, and why succulents rot

Why succulents rot, and what a cactus mix is actually doing

Succulents get sold as the plant you can't kill, which sets everybody up for a fall, because you absolutely can kill one and the way you do it is by being kind to it. They store their own water in the leaves, so they're built for ground that dries right out between drinks, and the standard bag of potting mix in a pot on a shady verandah is the opposite of that.

What a cactus mix does differently

Brunnings Cactus and Succulent Potting Mix is built coarse and gritty with less water holding material in it than a general mix, so water runs through it and air gets back into the gaps quickly afterwards. That's the whole point of it. A succulent root needs to be wet briefly and then dry, and a mix that stays damp for a week gives the rot fungi everything they need while the plant sits there looking fine right up until it doesn't.

Go by what the bag says it's for rather than by anything I tell you about the formulation, since blends get changed and the bag is the current word on it.

The pot matters at least as much as the mix

Put the best cactus mix in the world into a decorative pot with no hole in the bottom and you've built a bath. This is the commonest way a succulent dies indoors and it's completely invisible, because the top 2cm looks dry while the bottom third never does.

• A drainage hole is not optional. If the pretty pot has no hole, keep the plant in a plastic pot that does and sit that inside the pretty one, then lift it out to water.
• Terracotta breathes through the wall and dries faster than plastic or glazed ceramic, so it's the forgiving choice if you're a generous waterer.
• Go a size smaller than you think. A big pot holds a big volume of wet mix around a small root ball, and all of it stays wet.
• Tip the saucer out after you water. A pot standing in a saucer of water is a pot with no drainage.

How to water one

Soak it properly until water runs out the bottom, then leave it completely alone until the mix is dry the whole way down. Sticking a finger in to the second knuckle tells you more than looking at the surface does. Little daily sips are the worst option available, because they keep the surface damp without ever wetting the root zone, so the plant is thirsty and rotting at the same time.

They want much less water when they aren't growing, so a succulent that drinks weekly in the heat might want nothing at all for a month through the cold. Watering a dormant succulent on a schedule is how a lot of them go.

Stretching is a light problem, not a soil problem

If your succulent is growing tall and pale with big gaps between the leaves, that's etiolation and it means the plant isn't getting enough light. It reaches for a window it can't find. Changing the mix or holding back the fertiliser won't fix it and neither will feeding it more, because the plant is doing exactly what it should be doing in the light it's been given.

Move it somewhere brighter and do it gradually, because a succulent that's been indoors for months will scorch if you put it straight into full afternoon sun. The stretched growth won't shrink back, so if it bothers you the answer is to behead the plant and strike the top as a cutting, once the cut has been left to callus over for a few days.

In the ground, this is a different question

A bag of cactus mix is a container product and it isn't the answer for a succulent bed in the ground, where you'd be tipping 5 litres into a hole and wondering why nothing changed. An in-ground succulent bed wants the drainage fixed instead, which usually means raising the bed so water can get away, and working something coarse through the soil so it isn't holding on to every drop.

Shop related products

• Brunnings Cactus & Succulent Potting Mix 5L. Coarse and free draining, made for pots.
• Brunnings Perlite 5L. For opening up a mix that's holding more water than you want.
• Brunnings Propagating Sand 5L. Sharp sand for striking the cuttings off a stretched plant.

Did you know we carry plant pots and pot saucers in the shop as well, in a few sizes, and none of them are listed on the website. So if you're after something with a proper hole in the bottom, give us a ring on (08) 8536 4333 to check what's on the shelf or come and look through the garden centre. Bring the plant in if it's sulking and we'll work out which of the two problems you've got.

Read next

• How to stop root rot in your indoor plants
• How to choose the right pot for an indoor plant
• Brunnings Perlite, what it does and when to use it

I'm a chronic over-waterer, so everything I own sits in a pot with a hole in the bottom of it, on the theory that the pot can save me from myself.

Cheers,
Candeece

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