When a cactus outgrows the container it is in, it will need to be repotted if you want the plant to stay healthy. Repotting a cactus can be daunting, but if you protect yourself from thorns and prevent the cactus roots from becoming damaged, the transplant process should be successful.
Steps
Part 1 of 3: Remove the Cactus from the Old Pot
Step 1. Know when to repot
For most cactus species, it will be necessary to repot the plant once its roots begin to show from the drainage holes in the pot or once the crown of the cactus reaches the edge of the pot.
- This usually occurs every two to four years.
- Repot the cactus during the dry season, usually in late winter or early spring. The roots could become damaged in the process, and the moisture could cause the damaged roots to rot.
Step 2. Put on gloves
Put on thick leather gloves. The material needs to be thick so that it helps protect you from the plant's sharp thorns.
Gloves alone may not be enough to protect your skin, but even if you choose other protective measures, it is recommended that you also include thick gloves among them
Step 3. Loosen the soil
Run a dull blade around the inside perimeter of the pot, using a motion similar to using a saw to help loosen the soil around the edge. Continue as needed, until the soil begins to surface as a solid mass.
- If you have a plastic pot, you may also want to try squeezing along the sides of the pot to loosen the soil. Also, tap along the sides of the pot with a dull blade to help loosen the soil.
- The soil surrounding the root mass should be loosened completely before removing the cactus. Otherwise, you risk damaging the plant.
Step 4. Lift the cactus using a newspaper
Place a few sheets of newspaper on top of each other and fold them in three to create a thick, sturdy strip. Wrap this strip around the cactus. Grab this strip carefully, pressing it against the cactus and lift the strip and cactus out of the pot.
Alternatively, you could skip the newspaper and use an old pair of barbecue tongs to pull the cactus out. The idea is simply to keep your skin as far away from the cactus spines as possible
Part 2 of 3: Preparing the Cactus for Your New Pot
Step 1. Clean the roots
Place the cactus on a countertop and use your fingers to remove large chunks of soil from the roots. Also, carefully separate the roots.
- The roots don't need to be completely cleaned, but most of the loose debris pieces need to be removed.
- Continue to hold the gloves during this part of the process.
Step 2. Inspect the roots
Check for signs of rot, disease, or pests. Treat these issues as needed when you are aware of them.
- Apply a fungicide to get rid of rot or other fungus.
- Apply a mild pesticide to get rid of any pests.
- Use small scissors to cut any roots that appear dehydrated or dead.
Step 3. Consider pruning the roots
Root pruning is quite controversial, and the cactus will likely survive the repotting procedure even if you leave the roots alone. Root pruning can help the plant thrive more efficiently, however, especially when done right.
- The large tap roots absorb very little nutrients. They carry and store nutrients, but they don't actually absorb a lot of them, so they don't help the cactus grow faster.
- Cutting the largest roots can promote the health of the capillary roots, which are involved in the absorption of water and nutrients.
- Use a sharp, clean blade to cut the primary tap root from one-fifth to one-half of its current size. Also cut the largest roots, shortening them by one-fifth to one-half of their size.
Step 4. Let the roots dry
Keep the cactus in a warm, dry area for about four days to allow the roots to dry out a bit.
The roots could be damaged when you remove the plant from its pot, and any fractures could become infected with fungus or rot. The roots will likewise be vulnerable if you decide to prune them. Allowing the roots to dry removes this risk of infection
Part 3 of 3: Plant the Cactus in Its New Pot
Step 1. Choose a pot that is one size larger
When choosing a new pot for your cactus, you should choose one that is only one size larger than the one you removed the plant from. Anything bigger can cause problems.
- If a pot is too large, the soil will eventually hold more water. This water can remain around the roots and eventually cause them to rot.
- Large pots should be avoided for varieties whose roots tend to rot, such as Astrophytum, Ariocarpus, Lophophora, Aztekium, and Obregonia. This is not that important for hardy species, however, such as Cereus, Trichocereus, Hylocereus, Stenocereus, Myrtillocactus, and Opuntia.
Step 2. Put some soil in the new pot
Place some coarse growing compost in the bottom of the new pot. Use enough potting soil to keep the cactus planted at the same depth it was originally planted inside the old pot.
You can also consider placing a layer of drainage material, such as gravel or earthenware shards, at the base of the pot before adding a layer of soil
Step 3. Wrap newspaper around the cactus
If you no longer have the newspaper you used when you removed the cactus, prepare another strip with some overlapping sheets and fold them into three parts. Wrap the newspaper around the cactus's body.
- Make sure you have a good grip on the cactus through the newspaper.
- You should also use thick leather gloves during this part of the process.
- If you don't have a newspaper at your disposal, old, clean barbecue tongs can work too.
Step 4. Hold the cactus in the center of the pot
Carefully, grab the cactus using the newspaper and place it in the center of its new pot. Place it on the ground or just above the bottom of the pot.
Never press the cactus into the ground. You will cause severe root damage. You will need to carefully cover the roots with soil to keep the cactus stable without causing damage
Step 5. Add soil around the cactus
Carefully cover the space around the cactus with more coarse growing soil. Sprinkle as much as necessary to keep the cactus in the center of the pot without compacting the soil.
- Once the hips are roughly half filled, gently tap the sides of the jar. This helps the soil settle on the roots avoiding pressure and jolts. Repeat this step one more time when the hips are completely filled.
- At this point, you also need to make sure the plant isn't too deep or too high. Carefully, adjust the height of the cactus in the pot as needed so that the green part emerges from the ground, and that the brown root portion remains under the soil.
Step 6. Consider adding compost and gravel
While not strictly necessary, a layer of compost can help maintain the correct acidity of the soil and a layer of gravel or grit can improve drainage.
- The compost should be slightly acidic, with a pH between 4 and 5.5. Stir the compost into the soil along the sides of the pot.
- Spread only a thin layer of gravel on the soil surface, spreading it around the base of the cactus.
Step 7. Give the cactus some additional time to recover
For hardy species, wait a few days to a week before watering the cactus so it can continue to dry out and recover. For species with roots prone to rot, wait two to three weeks before watering.
