The prickly pear cactus has more than one hundred different species across North and South America. These cacti are characterized by flat, club-shaped pads that have either small barbs or long spines, depending on the species.
With so many species of prickly pear cactus, you can even find some that can survive in USDA hardiness zone 4 regions.
Being a succulent, the prickly pear cactus can absorb and store a significant volume of water in its body for use in the event of drought. This means it can survive long periods without being watered, but the same attribute also makes it very susceptible to overwatering. Constant and prolonged overwatering can cause root rot and even death for these plants.
In this article, we will discuss the signs of an overwatered prickly pear cactus, as well as how you can remedy the situation and save your plant. If you are currently faced with this problem and need some guidance on how to proceed, then keep reading.
What are the signs of an overwatered prickly pear cactus?
Cacti are extremely low-maintenance and, because they have adapted to the desert climate, can survive on very small amounts of water. Thus, many people end up killing their cacti by being too generous with their watering.
Furthermore, an overwatered cactus can often plump up and appear to grow, giving the impression that it is happy and healthy, when in reality the roots have been damaged and the plant will soon show signs of distress.
It is critical to keep an eye out for signs of overwatering so that you can correct it as soon as possible. If the problem is caught early enough, it may just be a matter of reducing your watering to rescue your cactus from certain death.
The signs to look out for are discussed below.
A cactus that has been overwatered may become dull green in color. It may also turn yellow as a result of chlorosis. Chlorosis is the yellowing of foliage due to a plant’s inability to produce chlorophyll, which is the pigment that gives plants their green color. If the plant’s roots are compromised and it is no longer able to absorb nutrients from the soil, its ability to photosynthesize and produce chlorophyll will be impacted, and it may also experience stunted growth.
Root rot can be identified by the presence of soft, brown spots on the body of the cactus. Root rot occurs when a cactus is left to sit in waterlogged soil for too long, causing the roots to deteriorate and rot. Due to the roots’ loss of function, the plant will be unable to absorb its required water and nutrients from the soil. Meanwhile, the rot in the roots will also start to spread through the rest of the plant, and the brown spots on the body of the cactus are a sign of this spread.
Small black spots
Fungi thrive in warm, moist environments, and fungal growth is a frequent side effect of overwatering.
If you notice small, black, circular spots on your cactus, this could indicate the presence of a fungal infection. Other signs to look out for include discolored scabs, soft areas, and sunken spots.
When a cactus is suffering from root rot, it will often emit an unpleasant, rotten smell, described by some as sulfurous or compost-like. This odor is caused by bacteria that grow in an oxygen-deprived environment, such as the bottom of a waterlogged pot.
If you are concerned that you may have overwatered your plant, it is a good idea to inspect the roots for any signs of rot. Rotten roots will be brown or black in color and will feel soggy, whereas healthy roots are firm and white.
The extent to which the root rot has progressed will determine whether or not you will be able to save the plant.
How can I save my overwatered prickly pear cactus?
If there are no serious signs of overwatering, such as rot, all you need to do is to stop watering the plant for a few days and wait for the soil to dry out. If there is any standing water in the soil, allow it to drain away properly.
Do not water the plant again until the top two inches of soil have completely dried out, and make sure that excess water has a way to drain from the pot.
If possible, make small holes in the soil around the roots with a pencil; this will allow more oxygen to reach the roots while also helping the soil to dry out faster.
If the cactus is situated near a humidifier or in a particularly humid room, you may need to move it. These plants do not like high humidity and this will only increase the chances of a fungal infection.
Move your plant to a spot where it will receive more sunlight and the best possible air circulation. This will help moisture evaporate faster from the soil and from the plant itself. A bright, sunny environment is ideal for cacti, which thrive in desert-like climates. A great place for your cactus is next to a south-facing window.
If your cactus is showing signs of damage, such as yellowing leaves or stunted growth, you will need to assess the extent of the damage. To do this, unpot the cactus and brush the soil away from its roots with a soft-bristled brush.
If the majority of the roots are white, that means very minimal damage has been done. As long as the damage has not progressed too far, your plant should be able to make a complete recovery. Repot it using fresh, well-draining potting soil, and place it in a bright and sunny position to recover.
Repotting the prickly pear cactus
Fill your pot halfway with loose potting soil. Potting mixes designed specifically for cacti can be found in any garden supply store. Those that include coarse materials such as perlite will help aerate the soil and improve its drainage.
Taking care not to damage the roots, bury your cactus about an inch deep in the new soil and fill the pot with more soil as needed.
If any roots have turned brown or black, this indicates root rot. You will need to cut away the damaged roots to prevent the spread of infection and encourage the growth of new roots in their place.
Cut away the rotten portions with a sharp, sterilized knife. In the event that any rotten bits are left behind, the disease can still be spread throughout the plant.
Keep the cactus out of the soil to allow it to air-dry for a few days, until scabs have formed on the parts that you cut. Once the scabs have dried completely, it can be transferred to a clean pot filled with cactus potting mix, according to the steps outlined above.
A different procedure must be followed in the event that your cactus has a fungal infection, signs of which include small, discolored spots, mushy areas, and small sunken areas. If the fungal infection has spread to the roots of your cactus, it is possible that you will not be able to save it. In that case, your best option is to take a cutting from a healthy area of the dying plant, which will allow you to propagate a new plant.
It is important not to water your plant for the first week after repotting it, to give it time to recover from the transplant shock.
It is also critical to allow the soil to dry out completely before watering it again; if this is not done, the cactus will continue to show signs of overwatering and will eventually die. Stick your finger one to two inches deep into the soil and check for moisture. If the top two inches of soil are completely dry, you can restart the watering process.
How can I avoid overwatering my prickly pear cactus?
Cacti are unique in that they can store water in their bodies, which makes them extremely easy to overwater.
As mentioned above, always allow the top two inches of soil to dry out completely before watering your plant again. It should never be allowed to sit in water for an extended period, as this will waterlog the roots and cause root rot. Ensure proper drainage for your plant, and empty the saucer if any water accumulates in it.
When the time comes to water your cactus, give it a proper soaking so that all the roots have access to water. Keep watering until you see water draining from the pot’s drainage holes; this will also help to flush out any salts that may have accumulated in the soil.
While it may appear to be a minor detail, the type of container that you use can have a significant impact on the health of your plant. Because they are porous and wick moisture away from the soil, unglazed ceramic pots and terracotta pots are a great choice for succulents. Plastic and fiberglass are not the best materials, as they are non-porous and retain more moisture in the soil. It is also best not to use a metal container, because metal heats up quickly and can cause the cactus to burn; it also does not drain very well.
Whatever material you choose, make sure that the planter has drainage holes in the bottom to allow excess water to drain properly.
The type of soil you use is also extremely important. In order for water to drain effectively, the soil needs to be well-draining. Choose a mix that is sandy, pebbly, and porous. Organic matter should also be present in the soil, because this will retain moisture for the roots without waterlogging them.
The prickly pear cactus is a succulent, and is thus able to store water in its body for use during dry spells. This feature allows the plant to survive long periods without rain or watering, but also makes it more susceptible than most to the effects of overwatering.
The signs of an overwatered prickly pear cactus include a pale color, brown spots near the base of the plant, black spots on the skin, an unpleasant smell in the soil, and rotten roots.
If you think your prickly pear cactus has been overwatered, stop watering it immediately and allow the soil to dry out completely. If there are no noticeable signs of damage on the plant, this measure should be sufficient.
However, if you suspect root rot in your cactus, you will have to unpot it, discard the old soil, and remove the rotten roots before repotting it in fresh, well-draining soil in a pot that has drainage holes.
Avoid overwatering your plant in the future by only watering it when the top two inches of soil are completely dry.
Image: istockphoto.com / unkas_photo