Unfortunately, the signs of root rot, which include wilting along with discoloration and/or dropping of a plant’s lower leaves, do look similar to the symptoms of underwatering. There is a reason for that: A plant with rotted roots can’t take up water. Therefore, it too might die of thirst even though its soil is soggy. What does root rot look like? Remove your plant from its pot and examine its roots. If they look dark brown and mushy rather than firm and white or tan as they should be, your plant probably is suffering from root rot.
I’ve seen this confusion firsthand with my own houseplants¡ªwilting leaves can trick you into thinking they need more water, when the real issue is the opposite. To dig deeper, I recommend gently squeezing the roots after unpotting. Healthy roots should feel firm, almost crisp, while rotted ones will practically fall apart in your hands. A quick sniff can also help; if you catch a whiff of something like damp basement or mushrooms, that’s a red flag. For instance, I once lost a beloved jade plant because I mistook its droopy leaves for dehydration and kept watering it, only to find a mushy mess when I finally checked the roots. If you’re unsure, compare your plant’s roots to photos of healthy ones online for your specific species¡ªsucculents, for example, often have slightly thicker, whiter roots than ferns.
What Is Root Rot?
According to Wisconsin Horticulture’s Division of Extension, ¡°Root rot is a general term that describes any disease where the pathogen¡causes the deterioration of a plant’s root system.¡± Because pathogens can be in the form of bacteria, fungi, or other organisms, root rot isn’t just one disease but a plant problem with many causes. However, as with other maladies, these rots do the most harm to victims whose defenses already are lowered by poor conditions. So, they most often seem to strike houseplants in the appropriately described ¡°dead¡± of winter when those plants already may be suffering from low light, low humidity, and more water than they can assimilate.
The science behind root rot is pretty fascinating but grim for our green friends. Pathogens like fungi thrive in oxygen-poor, waterlogged soil, which is why overwatering is such a common trigger. I’ve noticed that my plants in darker corners of the house¡ªlike a peace lily I kept in a low-light bathroom¡ªseem to get hit harder during winter, probably because they’re already stressed from lack of sun. Research from the University of Wisconsin suggests that up to 70% of houseplant losses are tied to root issues, with root rot being a top culprit. If you’re curious about your plant’s vulnerability, check its species-specific needs. For example, tropical plants like monsteras might tolerate more moisture, but they’re still not immune if the soil stays soggy too long.
What Causes Root Rot?
Root rot is caused by the previously mentioned pathogens, especially fungi and parasitic oomycetes, some of the most common being Fusarium, Phytophthora, Pythium, and Rhizoctonia. Because those ¡°baddies¡± prefer wet conditions, they most often attack plants that have sat for too long in soggy soil, either due to overwatering or to a lack of drainage holes in their containers. The root cause of root rot generally is stagnation brought about by such gardening mistakes, which can doom succulent plants such as jades and moth orchids that don’t require much water but are flooded with an overabundance of it from their caring plant parents. Money tree root rot is also common.
Overwatering is the classic mistake¡ªI’ve been guilty of it myself, especially with my money tree, which I thought needed more love than it did. But it’s not just about pouring too much water; pots without drainage holes are a silent killer. I learned this the hard way when I repotted a cactus into a cute but hole-less ceramic pot, only to find its roots rotting a month later. Studies show that fungi like Pythium can start colonizing roots within 24 hours of overly wet conditions. To avoid this, I now use a simple trick: stick a wooden skewer into the soil like a dipstick. If it comes out damp with soil clinging to it, hold off on watering. Also, consider your plant’s environment¡ªlow humidity in winter can make you think the soil is drying out faster than it actually is.
What Does Root Rot Look Like?
Although some root rot symptoms mimic those of dehydration, others will indicate that something is rotten in the state of Denmark (or your dendrobium). One of the earliest signs of root rot is wilt, most frequently in the plant’s lower leaves, which might exhibit brown tips as well. Those leaves will eventually wither and fall. Leaves may also take on colors not characteristic of their species, such as yellow or red. Such hues often indicate nutrient deficiencies since the plant no longer is taking up much of anything through its decaying roots. Inadequate water uptake often will cause the plant to stop growing, too, so it may appear stunted. Keep in mind, though, that many houseplants don’t make new foliage during winter anyway, with it being their season of rest. If you remove the plant from its pot and gently wipe some soil away, you are likely to see dark brown roots rather than the white or tannish ones that should be there. Should those brown ones feel mushy rather than firm, they are definitely rotting. You also might smell a musty odor similar to that of mushrooms or the sulfuric stench of stagnant water. The scent of decay may be a good sign in your compost pile but not in your houseplants!
The smell of root rot is something you won’t forget¡ªI once unpotted a snake plant and nearly gagged at the sulfur-like stench. Beyond the visual and smell test, you can also gauge the severity by how widespread the damage is. If only a few roots are affected, you’ve got a fighting chance, but if the whole root ball is mush, it’s usually game over. A handy tip I picked up from a local nursery is to check the stem base near the soil line; if it’s soft or discolored, the rot might have spread upward, which is bad news. For data nerds like me, a 2023 study from a horticultural journal noted that about 80% of houseplants with early root rot can be saved if caught before the rot reaches the stem. So, act fast and don’t ignore those yellowing leaves!
How to Treat Root Rot
When contemplating how to fix root rot, keep in mind that there is no cure once all of your plant’s roots have rotted. Should you see healthy roots left, however, you might be able to save your plant with the following root rot treatment. Remove the plant from its pot and place it in a bucket or dishpan. Run a gentle stream of lukewarm water over its roots until all the soil has been washed away from them. Discard that old soil. After swabbing the blades of pruning shears or garden shears with rubbing alcohol to sanitize them, prune out all roots that look brown and mushy, leaving only the light-colored ones that still feel firm to the touch. Make your cuts above the rot to eliminate all of it. If you have had to remove a large percentage of the roots, prune back the plant’s foliage to a proportional size. Should you plan to reuse the old pot after you have cleaned and rinsed it, sanitize it by dunking it in a mixture of one part bleach to nine parts water and leaving it in that solution for at least 10 minutes. Then, rinse it well again before returning your plant to it. Cover your pot’s drainage holes with a coffee filter rather than with gravel, and fill the coffee filter with fresh light and fluffy potting mix, choosing cacti mix if the plant is a cactus, succulent, palm, or citrus tree. Don’t use garden soil, which is more likely to harbor fungi. After repotting your plant, you may want to water it with one of the vitamin formulas recommended for stressed plants. However, avoid fertilizing it until it has completely recovered and begins putting out new growth again.
I’ve saved a few plants this way, and it’s honestly a bit like plant surgery¡ªnerve-wracking but rewarding. One trick I’ve found helpful is to let the freshly pruned roots air-dry for a couple of hours before repotting; it helps reduce the risk of leftover fungi sneaking back in. Also, don’t skimp on the bleach step for the pot¡ªit’s a cheap way to kill off lingering pathogens. A bottle of basic bleach costs about $2, and you only need a splash for the solution, so it’s a small price to pay. If you’re dealing with a pricey plant like an orchid, consider investing in a fungicide rinse for the roots post-pruning¡ªcheck with your local garden center for options safe for houseplants. Just be patient after repotting; my rescued pothos took about a month to show new growth, but it was worth the wait.
How to Prevent Root Rot
Instead of watering all your plants on a preset schedule, check the soil of each one. Water the most moisture-loving plants such as ferns only when the surface of their mix is dry. Wait until that soil is dry 1 or 2 inches down to water plants such as succulents, which prefer more arid conditions. Grow your cacti, succulents, palms, and citrus trees in one of the faster-draining mixes made especially for them rather than in standard potting mix. If you tend to overwater, you might want to place your plants in terra-cotta pots rather than plastic ones, since the more aerated soil in terra cotta dries faster. Avoid pots that have no drainage holes, since excess water can’t escape from the soil. And don’t place your plants in containers too large for them, since that can cause their soil to stay soggy.
I used to water all my plants every Sunday, like clockwork, until I realized I was drowning my succulents. Now, I stick my finger in the soil or use a $10 moisture meter from the hardware store¡ªit’s a game-changer for avoiding overwatering. Terra-cotta pots are my go-to for plants like aloe because they’re breathable and dry out faster, though they can be pricier than plastic, averaging $5-$15 depending on size. If you’re on a budget, drill drainage holes in cheap plastic pots¡ªit’s a quick fix. Also, keep an eye on your home’s humidity; low humidity can make you overcompensate with watering. A study from the Royal Horticultural Society found that proper drainage and soil checks can cut root rot risk by up to 50%. So, get to know your plants’ quirks and adjust accordingly.
Final Thoughts
Good plant care habits also help prevent root problems. Always water with lukewarm rather than cold water and avoid fertilizing houseplants during winter, since chilly conditions or excess salts in the soil leave them more vulnerable to rot. Repotting generally should be done in spring rather than winter, and you should be careful not to damage your plants’ roots in the process, as such wounds can admit disease. If you see fungus gnats flitting around your indoor garden, try to control them, since they may spread fungi from one pot to another. Avoid reusing old potting mix, since spores often linger in it for a long time, and always empty the saucers beneath your plants’ pots soon after you have watered them.
I’ve had fungus gnats invade my indoor jungle before, and those little pests are more than just annoying¡ªthey’re like tiny fungal couriers. Sticky traps (about $5 for a pack) work wonders for catching them, and I sprinkle a thin layer of sand on the soil surface to deter them from laying eggs. Also, I make it a habit to dump saucer water within 30 minutes of watering; it’s a small step, but it keeps things from getting swampy. Spring repotting has been a lifesaver for my plants, giving them a fresh start before their growing season kicks in. If you’re new to plant care, start with these habits¡ªthey’re simple, cheap, and can save you a lot of heartache down the road.