Root rot is one of the most common and damaging ailments snake plants can suffer from. Although these plants are very tolerant to many environmental conditions, rotting can be dangerous for the plant’s health. A severe rotting situation can literally destroy a plant from the ground up. With any problem, prevention is the best policy, and root rot can be stopped if caught early. In this article, I’ll explain how root rot happens in a snake plant, how to diagnose and treat it and, most importantly, how to prevent it.
What is a root rot?
Plant roots absorb water, nutrients and oxygen from the soil. But when the soil is too wet for a long time, the roots begin to slowly suffocate. Pathogens attack the weakened roots and it starts decaying. Affected roots turn into a brown or black mush that can’t absorb nutrients from the soil. This ultimately affects the entire plant, as it doesn’t receive necessary resources to grow.
What causes root rot in a snake plant?
Root rot can have two main sources – one is a prolonged exposure to wet and soggy soil and another is presence of fungus in the soil. Wet soil can be a result of many different things. It causes plant roots to die due to a lack of oxygen. As the problem continues, they start to slowly rot away. The other source, fungus may lie dormant in soil and suddenly flourish when it has a suitable moist environment. However, sitting in wet soil for an extended period seems to be the most common cause of root rot in snake plants. Here are some important contributors to this problem.
Watering too frequently
Watering your snake plant before the soil gets a chance to dry out is a classic setup for rot. Sansevieria are drought-tolerant species and require less water, so they shouldn’t be watered like most houseplants. The best way is to water them deeply but less frequently. You can do this weekly or biweekly, to ensure that the top layer of soil dries out. Constantly moist soil provides a breeding ground for root rot.
Be very careful while watering the snake plants in winter, when they are in dormant state. They require water around once a month during these times. So continuing the same watering schedule as in the growing phase means unintentional overwatering. Check this watering guide for more information on how to water Sansevieria.
Containers that lack sufficient drainage are a major no-no for Sansevieria. Pots for snake plants must have drainage holes to let excess water escape. Always make sure to place a saucer under the pot and discard the drained water after some time. If you let the water stay in the saucer, it can still make the base layer of soil sodden. One useful safety practice is to place the pot on pebbles to lift the pot base above the water line.
While container plants are at more risk of overwatering, garden plants are not immune to root rot. Most garden root rot issues can be prevented by taking precautionary measures to improve soil drainage before planting.
Snake plants should be placed in appropriately sized containers. You may be tempted to give your plant roots extra growing space while saving yourself some future repotting efforts. But big pots mean excess soil and extra moisture, which is a bad idea especially for succulents like Sansevieria.
Choose a pot that is just big enough to hold the root ball of the plant. And increase the pot diameter by 1-1.5 inches every time you repot it (usually every 2-3 years). Here’s a guide for picking a perfect pot for your snake plant.
Old and dense soil
Potting mix for snake plants must be porous and fast-draining. Heavy soils such as pure garden soil are too dense to quickly let the water pass through. Dense soil can stay waterlogged for long periods and allow harmful pathogens to grow in it. This causes and encourages the root rot. Mature old soil also tends to become compact and retain more moisture.
Another issue with the old soil can be salt overload. If you use hard or salty water, those dissolved minerals keep accumulating in the soil. The salinity of soil not just reduces infiltration, it also causes extra plant stress.
Using contaminated tools
Whenever you are pruning, propagating or repotting a snake plant, it’s important to use sterilized tools. Pathogens can cling to the non-sterilized tools and easily infect healthy plants. Exposed areas of plants (stubs after trimming down the leaves) make them more vulnerable and prone to infection. So, remember to disinfect your equipment before reusing them on other plants.
Not changing the water during propagation
New tiny roots of snake plants can rot in the water propagation process. This can commonly happen while using leaf cuttings. When you are propagating a snake plant in water, it’s very essential to frequently replace the water. If you forget to change the water every 3-4 days, the lower end of the leaf and the roots (if any) develop a fishy odor and start rotting.
Symptoms of root rot
Early detection of root rot is critical to take an early action. But unfortunately, the first symptoms of this disease occur beneath the soil surface. Plant growers are often not aware of the problem until it is advanced and visible in other forms. So, when your snake plants start showing symptoms of root rot, act immediately to resolve the problem as quickly as possible.
Appearance of the leaves
Slow growth and yellowing leaves are some early warning signs that the plant roots might be struggling. Because snake plants are already slow-medium growth plants, you may not notice the growth slowing down even more. However, yellowing of the leaves is a prominent indication of root rot in the case of Sansevieria. The entire root system may not yet be affected.
When roots are damaged, leaves begin to wilt, become soft and mushy, turn yellow or fall off. Usually the outer leaves get affected first, followed by the rest of the foliage. If your snake plant is drooping and the leaves are turning yellow for seemingly unknown reasons, you may want to check the roots.
It’s a good idea to check the soil and roots if you see any leaf discoloration. Loosen the soil around the base of the plant and gently remove the plant from its pot. Carefully shake the soil from the plant roots and inspect them. Right away if you notice a bad smell of decay coming from the soil or roots, it is another signal of root rot.
Healthy roots have an earthy scent or no scent at all. But as the disease progresses, your snake plant may develop the odor of rotting plant material. It becomes increasingly obvious with time, if the problem is not treated. When you recognize the smell early on, it may help to identify the problem sooner.
Dark mushy roots
After taking out the plant for examination, check the roots carefully. The healthy roots of the snake plant are light yellow or white, and firm to touch. With the disease, they start to become limp and slowly change color. The roots affected by root rot look brown or black. If you touch them, they’ll feel a little soft.
As the root rot progresses to its worst stages, the infection turns the roots into complete mush. Healthy portions of root turn more dark and mushy as the roots slowly die. Severely damaged roots may literally fall off the plant when you pull them slightly.
Appearance of the soil
Soil that stays wet for too long indicates a possible root rot problem down below. Check your plant soil with a finger or a moisture meter and see how damp it is. Feel the soil 2 inches below the surface. If it’s wet even after days from watering, that’s not a good sign.
Excessive water, overly wet soil or poor drainage are causes of root rot, but fungus in the soil make the problem worse. Too much water provides the perfect breeding ground for fungus. Red leaf spot and southern blight are common fungal diseases that attack the snake plants already weakened by overwatering. Visible fungus on the soil surface or leaves is often accompanied with some root rot.
How to save your snake plant from root rot?
You may be able to revive the plant during the early progression of the disease. Once a root rot is identified, determine if the plant can be saved. If the entire root system has already become mushy, the only option is to throw away the plant. Discard it with care and don’t let it come in contact with other healthy plants. Make sure to sterilize the tools and pot afterwards.
However, if the rot is widespread but there are still living roots, you can try to bring back your plant to good health. Even though most of the foliage is dead, as long as some healthy, firm roots exist, a snake plant can grow back new pups. The first and most important thing is to act quickly. Start the treatment ASAP to give your plant the best odds to survive.
Treatment for rot
- Start the treatment by removing your snake plant from the soil and washing the roots under running water. Be gentle with the plant and try to wash away as much infected soil as possible. After the roots are cleaner, inspect them carefully.
- Take a sharp, sterilized pair of shears to trim away all of the affected parts. Cut off mushy, brown parts of the root system. You may have to remove a significant amount of roots if the plant is badly affected. If this is the case, sterilize the shears again and prune back one-third of the leaves on the plant. Start with the yellow, wilted and older leaves. Oldest leaves are on the outside of the plant, as new leaves grow from the center. Trim off the flower stalk if it’s there. This will reduce the plant stress, as it will not need to support as many leaves.
- This step is optional, but recommended. Dip the healthy roots in a fungicide or add it in the soil to kill off any possible root rot fungus. In the next section, there is a list of fungicides. You can use any one of them.
- The last step is to repot the plant in fresh soil. Use a clean, dry, sandy potting mix and a container with good drainage. If you are reusing the old pot, wash it thoroughly with 1 part bleach and 9 parts water for at least 10 minutes. Then rinse it off with clean, hot water and let it air dry. Next, plant your Sansevieria in a pot at the same depth as before.
Treatment for the fungus
To ensure that the pathogens get completely wiped off and wouldn’t easily attack the plant in future, treat your plant with some fungicide. Here are some commonly used types.
This common kitchen spice is a natural fungicide with low toxicity. It contains an amazing ingredient called cinnamaldehyde. Research shows that this compound is effective against fungal infections on over 40 different crops. Cinnamon is used for reducing soil gnats, protecting seedlings and preventing root rot. For an added benefit, the scent also repels cats and dogs, for whom snake plants are mildly toxic.
To treat your troubled snake plant, dust some cinnamon over the roots. Apply it on the stumps after the diseased leaves have been trimmed away. Don’t forget to mix some in the soil as well. You can also use cinnamon essential oil, but dilute it in some carrier oil.
Another organic multipurpose product that you can use is neem oil. This oil is extracted from the kernels of neem fruit. It can get rid of fungi, sooty mold, mildew etc. This natural pesticide will ward off insects, nematodes and bacteria as well.
It is normally used in a spray form. Add 1 teaspoon (5ml) neem oil in 1 quart (1 liter) of warm water with half teaspoon of mild liquid soap. Shake it and spray it on just the affected parts of the plant.
Hydrogen Peroxide (H2O2)
Another easily available potential root rot treatment is a solution of Hydrogen Peroxide. When a small amount of peroxide is added to the water, it breaks down into water and oxygen molecules. This helps control fungus gnats by providing oxygen to plant roots. While the leaves of a plant use carbon dioxide, roots still need oxygen.
Dilute about 1 teaspoons of 3% H2O2 solution in a cup of water. Then dip the roots and other affected parts in the diluted solution before repotting. It can also be mixed into the soil or added in the watering can. When you water the snake plant, add about 1 tablespoon of hydrogen peroxide to 1 litre of water. Use it either for dipping the roots, mixing in soil or while watering. Don’t try all the three as it might be too much.
Commercial fungicides can be inexpensive and effective on the fungus. But they can possibly damage the beneficial soil microorganisms. This can make the plant weaker and more susceptible to rot. So if possible, save it as a last resort.
- After repotting, leave the plant alone for a couple of days.
- Then carefully resume the watering schedule. Water the plant sparingly, until the roots recover and it starts producing new foliage. As the plant and root size is reduced, it will need less water. Water the plant only when the top of the soil is dry.
- Keep the plant out of intense sunlight. Place it in a moderately bright place.
- Avoid fertilizers until the plant is healthy again. The compromised roots won’t absorb the nutrients and might burn. Fertilizers are not medicines and shouldn’t be used on sick plants.
Hopefully, now your snake plant will recover and you’ll get your beautiful houseplant back.
- Krista E. Pearson, Basics of Salinity and Sodicity Effects on Soil Physical Properties
- Fungal Root Rots and Chemical Fungicide Use, Penn State Extension