When and how to transplant your indoor cactus

Cacti (arguably some of the easiest houseplants to grow) add a unique touch to our home interior with their distinctive geometric look. However, repotting them can prove a thorny challenge. This article will provide you with useful tips, tricks and methods for a hassle-free and painless cactus repotting session.

When should a cactus be replanted, and how often?

The best time to repot a cactus is during its growth period, from early March to early September. As a general rule, repotting sessions should take place every three to four years. However, they can be carried out sooner if your cacti are showing signs of pest attack, yellowing, or if their roots are coming out of their pots.

Why repot cacti?

We repot cacti to provide them with extra room for their roots (if we choose a larger pot to promote growth), but more importantly to offer our plants new potting soil, as over the years an excess of mineral salts builds up due to watering with hard water or water containing fertilizers.

Choosing the right pot for your cactus plants

There are a few things to consider when choosing a pot for your cactus: the diameter of the pot, its depth, the presence of a drainage hole and the type of material it is made of.

Diameter: Given that most cacti don’t need a wide space to thrive, simply choose a pot that leaves at least 2.5 centimeters (1 inch) of clearance around the base of the plant. This will give the plant plenty of room to grow. To promote growth, choose a pot whose circumference is 2 to 5 centimeters (1 to 2 inches) larger than the old one. To limit growth, use a pot of the same size.
Depth: To determine the right depth for your pot, you need to know the average root length of the cactus variety you want to transplant. Once you have found this length, you need to figure one or two extra inches to accommodate the potting soil under the roots. This space is important because it ensures good aeration of the roots.
Drainage hole: The drainage hole is not a detail, it’s a necessity, and if you choose a pot that doesn’t have one, we recommend you make at least one. It will allow excess water to drain away, preventing root asphyxia and root rot.
Plastic or clay: Although plastic pots are cheaper, lighter and easier to clean, their clay counterparts offer advantages when it comes to your cacti. Because they’re porous, they allow better air circulation and more efficient drainage of excess water, which promotes root health. In addition, the fact that they are heavier can represent an asset for stabilizing big or tall cacti.

Choosing the right potting soil for cactus plants

Cacti are plants adapted to arid environments and therefore require a specific type of soil, such as the Fafard’s CACTUS & SUCCULENT Potting Mix, made from sphagnum peat moss and sand. This soil mix promotes rapid drainage while preserving optimum humidity levels for these types of plants.

How to transplant cacti

To make your transplanting session a breeze, be sure to water your cacti a week or so in advance. The soil will remain slightly moist, making it easier to remove the roots from the pot without damaging them. Don’t forget that these repotting sessions are the perfect time to propagate your cacti with, as explained in the article How to Use Cuttings to Propagate Cacti and Succulents. All you need is a little potting soil and a few extra pots.

Steps to follow :

Choose a new pot slightly larger than the current one or of the same size. Make sure it is clean and features a drainage hole.
Partially fill the pot with potting soil, leaving enough space for the roots.
Carefully remove the cactus from its pot and gently spread out the roots. Cut off any dead or damaged roots.
Place the cactus in the center of the new pot and make sure that the collar of the plant is 1 or 2 centimeters (±0.5 inch) below the rim of the pot.
Fill the remaining space around the root ball with potting soil and press lightly, then place the cactus in a shaded area to help it adapt to its new environment. After a few days, expose the cactus to direct light and begin light watering, avoiding excess, as too much moisture can cause root rot.

Note: For oversized cacti (difficult, if not impossible, to repot), you can simply remove the first two to three centimeters of old potting soil and replace it with new potting soil, without removing the plant from its pot.

Pro gardener’s tip: How to repot cactus without getting pricked?

Here are a few tips to make handling your cacti less thorny.

Wear thick gloves
Use metal kitchen tongs
Create a handle with newspaper or thick cardboard

How to care for your cactus after the transplanting session

As mentioned in step 5 of the repotting procedure, you should place your cactus in a shaded spot after repotting. This will help it better adapt to its new environment. After a few days, it will be time to move it under direct light and start lightly watering it again to prevent root rot. For a quick reminder of how to care for cacti, see the article Cactus: Easy to care for plants.

Between March and July, fertilize once a month to help your cactus reach its full growth potential. A formulation such as 0.5-1-1 promotes root growth and a stronger cactus. Above all, we want to avoid having plants that wilt (rapid growth that’s both too thin and soft). The key: use a fertilizer with a low dose of nitrogen (N), and a higher dose of phosphorus (P) and potassium (K) to ensure more uniform growth of your cactus.

Fertilizing cactus with low dose of nitrogen

In conclusion, it’s worth remembering that, although prickly, cacti can be tamed with the right techniques. With these tips, repotting your cacti will become an easy, thorn-free operation!

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When and how to transplant your cactus