Root rot is the bane of succulent fans everywhere. While succulents are incredibly resistant to most diseases and pests, certain environmental conditions can result in a wilting stem, pale mushy leaves, blackening roots, and a distinctive fart-like aroma.
Although a few species of succulents enjoy abundant water, most are drought-tolerant plants that need their roots to dry out periodically. For these plants–aloe, agave, and most cacti, for example–root rot is often a death sentence.
The good news is that if you identify root rot quickly enough and change your general cactus care strategy, you can stop succulent rot from worsening.
How To Identify Root Rot in Succulents
The signs of root rot develop gradually, so they’re easy to miss until it’s too late. Many people grow succulents specifically because they tolerate neglect (such as infrequent watering). Ignoring your plant can prevent you from identifying root rot before it advances to the terminal stage. Observing your plant routinely and promptly addressing any negative changes in its appearance is the key to maintaining a healthy succulent.
When you inspect your succulent, check each part of your plant for the following symptoms (or circumstantial evidence) supporting a root rot diagnosis.
Changing Stem Composition
Is the plant’s stem firm and upright or soft and saggy (especially at the base where the stem meets the roots)? The latter indicates succulent root rot spreading from the roots to the stem.
Changing Texture of Leaves
When a succulent’s roots are rotting, the leaves become flaccid and eventually mushy. This often starts with the oldest leaves at the base of the plant, nearest to the roots.
Discoloration of Leaves
If your succulent’s leaves were once a vibrant green, but their color has dulled to a more washed-out shade, that can be a symptom of nutrient deficiency caused by root rot. Leaves on a rotting plant will turn a lighter shade of green or even grayish or yellowish. This typically begins with the oldest leaves at the base of the plant.
Changing Color and Texture of Roots
If you see other signs of succulent root rot, consider removing the plant from its pot and the extra growing medium so you can check the roots visually.
If the roots are soft and mushy (instead of firm and brittle), and they are turning dark brown or black (rather than their typical creamy white), those roots are rotting. You should remove them to save the plant. Also, when you remove soil from the roots, you may find that the outer layer of the root slides off, leaving only the inner core of the root attached to the plant.
Slow Growth Rate
If your plant’s growth is stunted, this can be a sign of root rot. However, this only applies during the primary growing season. During a plant’s dormancy (in the winter and/or summer), growth will slow naturally.
If your succulent is growing in a pot with no drainage hole, so that excess water is trapped in the bottom, that makes developing root rot much more likely.
Cool Growing Environment
For outdoor plants, freezing or exposure to a cold snap is another common environmental factor that raises red flags for root rot. Remember that temperatures as high as the 50s Fahrenheit can be too cold for many tender succulents.
If your plant is in a cooler area with less direct sunlight, that will temper its growth and, therefore, the amount of water it drinks. When water remains in the soil for an extended period, instead of drying out between watering sessions, that becomes another contributing factor.
Succulents prefer growing in poor, rocky soil, not the nutrient-rich potting soil made primarily of organic matter most plants prefer. If your succulent is growing outside in the ground (in ordinary garden soil) or in a planter containing inappropriate potting mix for a succulent, that is a major risk factor for rotting roots. In combination with other symptoms, it’s a good clue if the potting mix has no visible perlite.
Give your plant’s soil a quick sniff. If you catch a whiff of rotten eggs (sulfur), that indicates root rot. The smell results from bacteria build-up that grows in anaerobic conditions such as waterlogged soil.
Causes of Root Rotting in Succulents
Rotting succulent roots is a result of some combination of the following problems.
Soil-borne fungal infections and related bacterial growth lead to root rot and stem rot. The fungus can live dormant in the soil for extended periods, then wake up and attack your plant’s roots under certain conditions (usually too much moisture).
There is no good way for a home gardener to test soil for fungi, so you’ll need to focus mainly on avoiding the environmental conditions that encourage fungal growth. It can also help to use a potting mix or potting mix ingredients that are pasteurized or sterilized.
While there’s no way to guarantee that your potting mix is free from fungi, you can minimize the spread from one plant to another. Two ways to avoid inadvertently transferring fungi from plant to plant is to use fresh potting mix when re-potting your succulents (never reuse old potting mix from another plant or garden soil) and always sterilize your pruning knife or shears before and after using them on each plant.
Over-watering is frequently a primary factor in rotting your succulent’s roots. The excess moisture stimulates the growth of fungi and bacteria in the soil that can damage your plant’s roots. Over-watering typically happens when you water your succulents whenever you water the rest of your houseplants rather than looking for signs that your succulent actually needs water.
Succulents prefer well-draining soil full of sand, rocks, and other gritty material. In outdoor plants, root rot often results from planting succulents in garden soil full of clay or rich in organic matter. You might be surprised when an indoor potted succulent gets root rot because you used a high-quality potting mix, but the odds are that the potting mix contains too much compost, peat, and other organic matter. Rocky, sandy soil is much better for succulents.
No matter how well-draining your potting mix is, it’s still important to use a planter with drainage holes for excess water to escape.
Outdoors, if you’re planting succulents in the ground, choose an area with well-draining soil or consider adding drainage by integrating gravel into the soil (to a depth of at least a foot). You can also add a buried French drain to a particularly waterlogged area or move your outdoor succulents in a pot.
There are exceptions, but most succulents are not cold-hardy. Freezing temperatures will often result in root rot when the plant thaws. For the most sensitive succulents, this can also occur from cool temperatures, even if well above freezing.
Succulents are minimalistic feeders, so when you add too much fertilizer or the wrong kind, your succulent can’t absorb it and stays in the soil. For example, many houseplant fertilizers have too much nitrogen, so they are not recommended for succulents which prefer only occasional applications of a dilute, liquid, organic, balanced fertilizer. For more help choosing a good fertilizer for your succulents and using it correctly, check out our guide.
Pests and Diseases
Because succulents are so resilient, they don’t generally fall victim to pests or diseases unless there are multiple problems with the plant or the way you’re maintaining it.
For example, succulents can get mealybugs, but it’s rare for these pests to attack a healthy succulent, so if your plant becomes infested, your succulent probably has another underlying problem (such as root rot).
If you see any other symptoms, check out our guide to diagnosing and treating an ailing succulent. It’s also a good idea to review your overall succulent care.
How To Treat and Care For a Succulent with Root Rot
Root rot is difficult to cure, so many gardeners will tell you that you should throw out the plant if it sets in. The good thing is that if you catch it early, you can save your plant baby. The key is to use as many strategies from the following list as possible to improve your succulent’s odds of recovery.
Use An Appropriate Pot
If your succulent is small and only fills up a little of the pot’s interior, the pot is too big. Using a large pot for a small plant encourages root rot. The plant takes so long to drink enough water to dry out the soil that fungi and bacteria can grow unabated. In an appropriate pot, the soil will dry out within a week in the summer and two weeks in the winter.
Replant your succulent into a smaller pot or create a succulent arrangement by planting a collection of small succulents together in one pot.
If your succulent is currently growing in a pot with no drainage hole, you should re-pot it into a planter that does.
Remove Inappropriate Growing Medium
Since the fungi and bacteria that cause root rot grow in the soil, you should immediately replace the contaminated succulent soil. If your succulent is planted in garden soil or a standard potting mix not meant for succulents, get rid of it.
Using the correct soil for your succulent will help prevent and halt root rot by providing adequate drainage. We won’t bore you with the science, but research has shown this strategy worsens drainage. So remove these sorts of objects in a layer at the bottom of your pot.
To be clear, mixing small lightweight rocks like perlite or pumice with your soil does improve drainage. Just don’t keep them separated in a layer at the bottom.
Use Appropriate Growing Medium
Succulents can be grown anywhere, but only if you replicate their natural environment. They evolved to have such fleshy, water-retaining leaves because they grow in places where they may grow for many days or even weeks in dry soil. During these dry periods, they feed on the water and nutrients stored in the leaves.
That’s why they need a growing medium that retains minimal moisture and dries out quickly. The key is low amounts of organic matter (like compost) and high amounts of gritty inorganic matter (like sand and rock). You are unlikely to find that combination in any commercially available potting mix.
The good news is, you can make your own. Take a deep dive into succulent potting mix with our guide, which includes more detail about factors like soil pH.
Sterilize Your Equipment
Fungus and bacteria that contribute to root rot can easily be transferred from one succulent plant to another. An important root rot control strategy is sterilizing contaminated surfaces to avoid turning one succulent with root rot into a house full of rotting plants.
One significant opportunity for inadvertent cross-contamination is pruning. If you use tools (like a gardening knife or shears) to prune your succulents, you should sterilize them before and after using them on each plant. The best way to prune them is to wipe the blades with rubbing alcohol. This will kill any pathogens you might otherwise transfer from one plant to the next.
Another thing you can try, especially if you’re having repeated problems with root rot, is to sterilize the inside of your pot. Pots that are absorbent or have rough textures that trap bits of contaminated soil can transfer pathogens from one plant to the next or recontaminate a succulent you’ve re-potted in the same pot with fresh potting soil.
You can sterilize pots using alcohol, diluted bleach, or detergent. Plastic pots are more difficult to sterilize reliably.
Prune Rotting Succulent Roots
If you discover that some of your succulent’s roots are rotten, pruning is essential to save the plant. Using a sharp, sterile knife or shears, remove any discolored, soft, slimy, or smelly roots.
You may have to remove all of the plant’s roots. This doesn’t mean the plant is a lost cause. Succulents are amazing at self-propagation. They can grow new roots directly from the stem.
Change Your Watering Habits
The number one way to prevent root rot in the first place, and prevent it from recurring in a plant you’re trying to save, is to water your succulent correctly.
For most gardeners and all gardeners dealing with root rot, the correct watering frequency is less than your current watering schedule. Don’t make the mistake of simply giving the plant less water, but water just as frequently. This is the opposite of what you need to do.
Most succulents originate in environments where it rains infrequently but heavily when a storm does blow through. If you want to avoid rotting roots, succulents want thorough watering and then for their roots to dry out for at least a few days in between every watering.
For detailed information on how to water your succulent and a helpful water tracking card, check out our guide.
Fungicide can be used. However, not many gardeners use it for two reasons. First, suitable organic fungicides are expensive and are sold in large quantities, so buying the herbicide costs much more than buying a new succulent. Second, many types of fungi cause root rot, such as Pythium, Phytophthora, Rhizoctonia solani, Fusarium, Botrytis, Alternaria, and Sclerotinia.
Propagate Your Plant
If worst comes to worst, you can always give up, compost your succulent, and start over with a new plant. But sometimes you have a sentimental attachment to a plant, or it’s a rare type you can’t find at the garden store. In that case, consider pruning off the healthy part of your plant and propagating it. While it does mean your plant will be reduced substantially in size, a newly propagated stem cutting has a much better prognosis than a large plant suffering from a severe case of succulent root rot.