How To Repot A Cactus

One of the easiest plants to care for is the cactus. These plants are very easy to care for, especially houseplants, as they can go for very long spells without any water, as long as you give them enough light.

They are undemanding and slow-growing, and won’t wilt in dry atmospheres inside as many houseplants will.

But there is one drawback to these beautiful and unusual plants. Repotting them. Then you are faced with a tricky problem, as some cacti sport very sharp spines. 

The last thing you want to do is to spend ages with a tweezer picking out spines from your hands, but there is a knack to repotting cacti that stops this from happening altogether.

Here’s how to repot any kind of cactus safely.

Why Should You Bother Repotting A Cactus?

There is a misconception that once you buy a cactus and put it in your home or garden, that’s it. You don’t need to do anything else.

That’s only true with a plastic cactus. Yes, your cactus will go awhile without needing anything at all from you, but every few years or so, they will need a new home. 

While most cacti like being root bound (See also How To Repot Root Bound Tropical Plants), there is a point where the roots will get so crowded that they are no longer able to do their job, and soak up the moisture and nutrients they need to grow.

Another reason to repot a cactus is that some indoor cacti can be suffering without any outward, above-soil signs (see also Indoor Cactus Tips And Tricks). 

Your plant may be suffering from soil that is too tightly packed, not getting enough oxygen into the roots, stunting its growth and overall health. 

Perhaps the roots are sitting in water because you have overwatered it, or there isn’t enough drainage for the water to filter through, and without taking the plant out of the pot to check its health, you might not know about a problem until it is too late to fix it. 

How To Know When You Need To Repot A Cactus

Some cacti will grow quickly, and others will take years to outgrow their pots, so it can be tricky to know exactly when you should move a cactus into a new home.

It’s worth knowing that repotting a cactus at the wrong time can do the plant more harm than good, as many go dormant in the winter. 

It may shock or even kill off your cactus, as with the lower temperatures and lower light, the root growth will be weaker, making the plant vulnerable to overwatering, particularly in a larger pot.

While the general rule of thumb for repotting cacti is every couple of years, your plants don’t exactly keep to a rigid schedule. 

The growth depends on the species, the age, and the growing conditions, and all these affect how quickly a plant outgrows its current pot. 

The best way to find out if your cactus needs repotting is to simply slip the cactus out of its pot. Wearing gloves, gently put your fingers over the top of the soil, and tip the plant upside down. 

If the soil is dry, it will come straight out with no problems, keeping the soil in its shape.

Do this every month of the growing season, and that way you’ll spot any problems before they get out of hand, but be careful not to touch the roots. 

The best time to do this is during spring, or in the first few weeks of summer, when there isn’t much heat stress for the plant to contend with.

Keeping an eye on the root system allows you to see any issues before they kill the plant, and gives you a good idea of its overall health. 

Before You Get Started: Everything You Need To Repot Cacti

You don’t exactly need a huge amount of gardening tools to repot a plant, but when it comes to repotting cacti, there are a few things that will make your life much easier, especially if you need to repot a cactus that is covered in spines.

Here are the things you need to repot a cactus, and to make sure it will be in its best health when it’s settled into its new home.

Choose The Right Pot

The first thing you need is the right pot. Some indoor cacti plants will have shallow roots, just like succulent plants, so they do better in wider, shallow pots.

But it does depend on the species. If you are growing a cactus that looks like a large column, you will of course need to get a deeper pot for the roots to anchor themselves deeply into the soil.

The golden rule of repotting is to only go one or two sizes larger than the pot your cactus is currently in. This goes for nearly all types of plants unless you are doing a mixed planter that doesn’t include cacti.

The Right Soil

An essential part of repotting a cactus is ensuring you’re using the right type of soil. You can get cacti-specialist soil ready-made from any garden center or retailer, but it’s also easy enough to make your own.

It needs plenty of grit to give the roots lots of oxygen and promote free drainage, and this is the most important aspect. 

You can use horticultural grit for this, but there are alternatives. Some people like to use pumice, and others even cat litter!

Coir can make up an important part of cacti and succulent soil, but it needs to be responsibly sourced.

Generally speaking, most mixes form 1:1:1 parts of grit, compost, and coir compost. Make sure that the compost you’re using isn’t packed too full of nutrients, as this can do more harm than good. 

Make Your Life Easier With The Right Tools

While repotting plants doesn’t usually require any specialist tools, it’s a little different when it comes to repotting cacti. 

You’ll need the regular tools such as a little hand trowel and a pair of scissors, and a garden knife can come in handy, too.

You will need some protective gloves to protect your hands from the spines, preferably heavy-duty ones. 

For lifting out a spiny cactus, one of the best tools you can use is a humble piece or box made of thick cardboard. No, really. 

Grabbing the cactus with the cardboard, ensuring that it is between your fingers and the plant as a barrier, means that no spines can attack you.

You could also use silicone tongs or a cut-up kitchen sponge, but make sure you don’t squeeze the plant.

Top Dress Your Cactus

It’s not required, but a layer of grit on top of the soil helps to trap heat and moisture while stopping any leaves from rotting by being in contact with the soil. 

Is It A Good Idea To Feed Cacti?

You can feed cacti with a specialist cacti fertilizer sparingly during the growing season, following the manufacturer’s instructions.

Be careful not to fertilize cacti outside the growing season, as plants that go dormant during the winter need to have this period of rest to sustain healthy growth.

How To Repot An Indoor Cactus

Wait until the soil of a cactus is completely dry before you repot it. This helps immensely when it comes to repotting, as the soil lifts out in the shape of the pot.

This protects the roots, but that doesn’t mean you don’t have to be careful with them. Gently tease out the old soil from the roots with your fingers, discarding the soil, but ensure you don’t rip off the roots if you can help it.

Freeing the roots from the shape of the pot encourages them to settle into the new soil. 

Make sure that the new pot has a good drainage hole, and place a layer of grit or rocks at the bottom. The soil is usually much finer than normal compost, so you don’t want it to come straight out of the hole.

Add a layer of compost, and put the cactus in to test the height. Fill the pot, leaving the top two inches of the pot clear. Dress as necessary, but don’t water it until a week later. 

Final Thoughts

Repotting a cactus can be daunting and even dangerous, but as long as you use protective tools, and repot in the early growing season when the plant needs it and not before, it is a fairly simple process and keeps your plant healthy.

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