Troubleshooting

Bugging Out: Tackling Common Houseplant Pests and Diseases

Identifying problems and acting quickly saves plant lives!

You've done everything right. You found the right light; you're in tune with your plant's watering needs. Your plant is thriving, thank you very much! But, one day, you notice some strange little specks on the leaves. Leaning in, you take a closer look…oh 🤬. They're moving!

Your first reaction may be to throw the whole thing out, but don't do that! While creepy-crawly pests or mysterious moldy substances can certainly freak out the squeamish among us, identifying the signs early and going into treatment mode as quickly as possible will help your plant recover.

Identification

It's a terrible feeling to know your plant is either sick or overrun with pests. That's why knowing how to identify the common pests and diseases is critical as a plant parent, especially as your collection grows!

This section is for every plant parent to read—you'll want to know what to watch for. The earlier the identification, the easier to treat.

In the second half, we'll go over treatment methods to nurse your plant back to optimum health.

Fungus Gnats

Identifying fungus gnats is actually easier than you'd think. These are small pests but large enough to be easily noticeable. They look similar to fruit flies but stick around plants in general, especially those that you keep quiet humid with consistently moist soil—this is the perfect breeding ground for a fungus gnat to lay their eggs.

If while watering or checking in on your plants, you notice tiny, flying insects emerging from the soil or leaves…you may have the beginning of an infestation on your hands.

While the flying adults are more of a nuisance than anything, it's the larvae that can cause some real damage.

The larvae live in the soil and like to munch on your plant's tender new roots and can even spread disease in the process. Time to act!

Mealy Bugs

Mealy bugs can seemingly appear overnight, so it's good to keep an eye on your houseplants for any signs. If you see what looks like cottony white fluff on your plant's leaves or stems, it's likely that you have a case of mealy bugs.

They like to lurk in cozy, unnoticeable spots. For example, you may see them under leaves or right where stems join. It's common for them to hide out between the leaves of succulents.

The second you see a fuzzy, white bug on your plant, or cotton-like fuzz, get ready to act. These pests can kill your plants if left untreated.  Another danger is that they can spread between plants. The sooner you act, the better!

Spider Mites

Ugh, the dreaded spider mites. These can certainly induce that horrible itchy feeling when you spot them. They're so tiny; you won't see them unless you get really close to your leaves and stare for a while. From far away, it may appear that your leaves are losing color or that they are a bit dusty. That’s because they’re sucking the life out of your plant!

These pests aren't exactly like the others—they are related to spiders and ticks. They don't hurt people, though, so don't worry (about that).

If you don't catch spider mites right away (they are tiny—so they can go unnoticed), you may notice very fine webbing that looks like the home of a spider, particularly under leaves and around growing tips. If you see that, immediately stop and take a closer look to see if there's movement on the leaves as well.

Another way of identifying spider mites can be tiny white or yellow spots on the leaf, like pinpricks or a speckled appearance. Spider mites feed on leaves by sucking out their nutrients. They also thrive in drier climates, so keep an eye out in winter for sure. It starts with yellow spots, turns to yellow leaves, and then a dead plant. Escalates quickly, this one. Act fast!

Scale

Did you think we were moving onto diseases? Think again. While it may sound like a disease, scale is instead another creepy little pest that can cause serious harm to houseplants. They are pretty hard to spot at first because they don't move around. They look like tiny, dark bumps or lumps on your plant's leaves or stems and attach themselves to suck out the nutrients. They also leave behind a sticky substance euphemistically called "honeydew", which can lead to sooty mold or attract ants. Oof.

The size and shape of scale vary widely. They can be so tiny you may not notice them, and they can be round, flat, or oval. The good news is that you will likely notice them before they kill a plant—they are slower to infest than our ultimate nemeses, the spider mites. They do like to gather together, so if you see an area with a lot of brown spots, you may be looking at a scale infestation.

Aphids

More insects that suck the life out of your plant, aphids develop and travel quickly. They can develop wings and fly from houseplant to houseplant, swiftly taking over. That's why it's important to recognize them right away and then check the rest of your plants promptly.

You'll see them clustered at the ends of plants where new growth is coming through. How incredibly rude!

This can cause your new growth to look, well, not great. Sad looking new growth might be an indicator that aphids are afoot.

When you find them, they are tiny and can be light green (blending in with most plants), pink, white, or black. If you see a big group of these crawling around your plant, you've identified that you have an aphid problem.

Like scale, aphids are another pest that leave behind droplets of the sticky substance known as "honeydew." Ants like this stuff, so if you start to see those hanging around your houseplants, you may want to take a closer look.

Springtail

These bugs are attracted to moist conditions. They are extremely tiny, so you may not see them without a magnifying glass. They are found often in little colonies, so where there is one springtail, many more are surely nearby.

They can range in color, appearing black, brown, and white in different places. They live in the soil of our plants but luckily, they don't do as much harm as you'd expect. If you suspect springtails, test the soil with your finger and watch for springing. These bugs can jump pretty high—and they do it all together with their group. They can move about 3 inches each jump!

While they may be a little annoying, they don't actually hurt your plant. They feed mostly on decaying matter and fungi. You can act if they creep you out or their numbers are getting out of control, but you can also leave them be. Finally! One bugger that's not out to kill your plant!

Thrip

Thrips are tiny long bugs that crawl around on plants. They can be hiding out in the plant itself or in the soil. They can also fly, which means they can travel from plant to plant with some ease.

You'll most likely spot them on top of or under your plant's leaves.

They are long and slender and will be actively moving around. There are quite a few varieties of thrips—they can be black, white, brown or green.

A sure sign that you have thrips will be the black pellet-shaped drops they leave behind. In fact, these are often easier to spot than the thrips themselves. You may also notice white dried out areas on the plant where they've been feeding.

Whiteflies

Whiteflies are, well, little white flies that can appear on your houseplant. You may find them on the underside of your plant's leaves, most likely in a swarm. If you gently move your plant around, you will see a bunch of them emerge by flying around—yuck! Whiteflies also tend to thrive in drier climates.

Powdery Mildew

Have you noticed your plant is looking extremely dusty? Like, so dusty it actually looks like you spilled flour or something? That's not just dust—that is powdery mildew! When you see this on your plants, you need to act as soon as possible. While it can spread quickly, the good news is that it's fairly easy to treat and less serious than most other diseases.

This mildew can really thrive indoors, especially when the house is kept at around 70 degrees…which, unfortunately, is the temperature most of us like.

Dim lighting, stagnant air, and prolonged wetness are also the perfect conditions for powdery mildew to take hold and spread.

So keep an eye out if you notice these conditions and try to maintain better air circulation around your plants.

Sooty Mold

Do your plants look like they have been through a chimney? Covered in soot? Well, that is probably a case of sooty mold. It will show on the stems, branches, and leaves.

It's very easy to identify because it's such an eyesore—but you need to go a step further. The only way sooty mold will show up on your plants is if there's another pest. The pest is the major problem here! Both aphids and scale leave behind "honeydew" while they are feeding on your plant. And honeydew leads to sooty mold. So take a closer look at your plant to identify the culprit.

While the mold itself doesn't directly damage the plant, the pest certainly does and ultimately the untreated areas will block the leaf's pores and its ability to photosynthesize.

Leaf Spot

Houseplants often have spots on their leaves but having fungal or bacterial leaf spot is a whole different ball game.

If you start seeing spots on your plants that aren't caused by burns or any other explanation, you may have a problem with leaf spot.

You'll be able to tell its fungal leaf spot when there's a circular pattern with various shades of brown and yellow in the spot itself, not unlike a bullseye. In the case of bacterial leaf spots, you may notice irregular dark spots that look water-soaked in the center. They may have a halo or margin around them that is lighter brown or yellow. Eventually, the spots expand and combine with other spots, taking over large areas of the leaves.

Gray Mold (Botrytis)

Gray mold can be terribly destructive to plants. You'll know you have gray mold if you see leaves browning, new growth shriveling, and stems looking a bit wrinkly and shrunken. When a dead piece of the plant falls off the plant, you'll soon see a thick, puffy gray mold…hence the name. When it dries, the fungus releases spores into the air—spreading to your other plants! Once you've identified it, it needs to be treated immediately to prevent more damage.

Anthracnose

Anthracnose is another fungus-based disease. It looks similar to others at first, possibly turning the leaf tips yellow at first. But a sure sign is leaves that start looking like they have spots along their veins that are lighter tan or brown. Eventually, the leaf will become more and more covered in spots and finally fall off the plant.

Root Rot

The dreaded root rot. You're trying to help your plant and accidentally overwater once or twice…or more. Before you know it, no matter how much love and attention you're giving them, your plant seems to be slowly dying. Wilting and yellowing leaves can indicate root rot—especially if you have no other idea what is going on.

Root rot is the result of long-term overwatering. Overwatering leads to fungal disease because it thrives in soils that remain wet.

The fungal pathogens can quickly infect the rest of the root system as it is stressed and weakened from sitting in those wet conditions. The sooner you identify it, the better your chances of recovery. If your plant is dying in front of your eyes, check for root rot!

Remove the plant from the pot and check out some of the roots. You'll know it's root rot if, instead of healthy white roots, you're seeing black, mushy roots.

Nurse Your Plants Back to Health

When you've identified a plant that has a pest or disease—the first step is always to isolate. The last thing you want is for that pest or disease to spread to your other plant babies. From there, you can proceed to treating the suffering plant.

One quick note here: we try to avoid chemical pesticides in the home. While it may seem like the quickest method and the most obvious one, bringing toxic materials into your home isn't the best idea, and most pests can actually develop a resistance to it. So, instead, we'll stick to outlining only the safest and most effective ways to deal with those pesky pests!

Fungus Gnats

The easiest method to eliminate fungus gnats is a soap and water solution. You'll want to use a mild dish soap—which you can combine with water in a spray bottle to shake it up and spray all over the plant and soil. You can also use a diluted hydrogen peroxide mixture as well. You may need to treat several times before you see a complete improvement—it takes a while to catch all the larvae.

In addition, it can help combat the gnats if you place your plant in a brighter spot and let the soil dry out more. You may be overwatering, which fungus gnats love. Your plant, on the other hand, probably isn't loving it. Have you been letting dead leaves or other debris accumulate in the pot? It's common to think this is okay, but fungus gnats feed off that decaying matter.

There are also some sticky traps on the market to more passively take care of any of the flying adults that may remain after these treatments. You can even get nematodes for a very serious problem—which are tiny little worms that will eat the fungus gnats but leave your plant alone.

To prevent their return, avoid recreating conditions where fungus gnats thrive: consistently moist soil and decaying plant debris.

Mealy Bugs, Spider Mites, and Aphids

So, you've identified one of these pests on your plant. You've isolated the plant and are ready to take control. We'll outline a few possible approaches here. And you may even try combining methods to find what works best for you.

  • Rubbing alcohol. While this will kill bugs on contact, it must come into direct contact with the bugs to do anything—you can do this by applying with a cotton swab or soaked tissue. But that means you'll have to check every nook and crevasse of your plant. And it can take a couple of repeat applications to get rid of them all.
  • Wash the plant thoroughly. Simply hosing down the plant with a mild soap and water mixture can go a long way to help get pests under control. Test out the soap mixture on a small area of your plant first—some can be too harsh for sensitive plants! With the combination of the diluted soap in a spray bottle and the spray nozzle of your shower, sink, or hose, you can give the plant a thorough rinse. Don't get too crazy with the blast, though; you don't want to damage your plant.
  • Neem oil. This naturally derived oil is an extremely effective tool for pest control. You'll want to follow the instructions on the type of neem oil you get. But in most cases, you simply mix it with water and a bit of mild soap and spray it liberally all over the plant and soil.
Whatever treatment you choose, you'll need to stick with it and repeat the treatment multiple times to get rid of the pests entirely.

These pests often go into hiding without a host, so stay vigilant. They can also hide under or around the pot, so don't just check your plant.

Preventative measures include maintaining good air circulation and avoiding overly dry conditions. Spider mites in particular love warm, dry conditions. In addition, a bi-weekly application of neem oil can help deter pests of all kinds!

Scale

Scale are tricky little pests—they like to hide out in hard to reach places, can be hard to detect since they don't move, and their shells protect them from most treatments. But once you find them, you can kill them with rubbing alcohol. It just has to make direct contact to work—which means physically applying it with a cotton swab or Q-tip.

If it doesn't freak you out too much, you can also manually pry or pick them off.

You'll want to follow that by washing your plant with a mild soap and water mixture or a neem oil solution to catch any eggs or younger insects that haven't "latched" on yet. Scale be gone!

Thrip and Whiteflies

These tend to be faster moving pests, so the best course of action will be a good initial hose down, followed by a few repeat treatments of a neem oil solution. Luckily, with just those simple steps, you should be able to get these pests under control pretty quickly.

Diseases

Many diseases have the same treatment method, including:

  • Powdery Mildew
  • Leaf Spot
  • Gray Mold (Botrytis)
  • Anthracnose

For these diseases, the first step is to isolate the plant. Then, you'll want to take these measures to help your plant recover:

  • Prune or pinch off the affected leaves. Make sure to sterilize your tools afterward to prevent spreading disease to another plant.
  • Be diligent in your removal of any fallen plant debris from the soil.
  • Stop misting or providing additional humidity for your plant (for now). Most diseases thrive off humid environments.
  • Try bottom watering to ensure you don't get any moisture on the leaves.
  • Try a regimen of neem oil, focusing on a soil soak rather than spraying the leaves (at least in the initial treatment phase)
Once you've removed the infected leaves, the disease should drastically slow its spread.

Make sure that you keep the leaves dry and check them regularly. If you see any symptoms return, remove those leaves as well and continue your treatments.

Sooty Mold

Since sooty mold is the result of another pest—most likely aphids or scales. You need to treat the root cause to treat the sooty mold as well.

Once you've identified and initiated a treatment for the pests, you can remove the unsightly black mold by either wiping down each affected leaf with a damp cloth or pruning off the leaves entirely.

Root Rot

Root rot can be fatal to a plant—so treating it as soon as it's identified is key.

  • Remove the plant from its pot.
  • Wash away or knock soil off the roots. The more soil you can remove from the roots, the better—just try to be gentle. Then let the whole root ball dry out a bit.
  • Trim away all rotted areas. Make sure you have sterilized shears and trim away all black, mushy roots. It may seem like you're trimming a lot away, but you need to remove all of the infected areas, or it will spread further.
  • If you removed a lot of the root system, trim the plant back. Look, we know no one wants to trim their plant back, but chances are, if your plant is suffering from root rot, a lot of the leaves need to be trimmed off anyway. Plus, a plant needs balance between their root system and the growth it supports above the soil in order to thrive.
  • Repot the plant. Using entirely new potting mix, you'll need to repot the plant. If you are using the same pot, make sure it has drainage holes first. If not, put it away. Using a pot without drainage holes is asking for root rot to reappear. No matter what, make sure to clean it thoroughly using a 1:9 diluted bleach solution to sterilize the pot.

Root rot is scary to treat, but it's possible to combat it! After this process, definitely give your plant time to rest and recover before trying anything drastic.

Unfortunately, if you have a serious infestation of pests or disease on your hands, you may have to throw in the towel. It's never fun to admit defeat, but better to give up on one plant than risk spreading the problem to your entire plant family!

Prevention

So now you know how to identify and treat pests and diseases, but what about preventing them in the first place? Occasionally, pests and diseases are already in the soil when you bring home a new plant. While most reputable nurseries will do their absolute best to keep their stock healthy and pest-free, it's quite possible that one or two will bypass their measures.

When bringing home a new plant, it's best practice to isolate them away from your other plants.

Keep them under careful surveillance to watch for any lurking critters or emerging disease. As an extra precaution, you can replace the top two inches or so of soil with a fresh batch. In addition, when you store potting mix for later use, it's best to keep it in a well contained, dark, and dry space to ensure it doesn't become contaminated.

A Silver Lining

Pests and diseases on your treasured houseplants can be an incredibly stressful time. As long as you take the time to do regular examinations of your plants—leaf undersides and all—you can identify problems early and take swift action to save your plant babes.

There are many rewarding experiences in tending to houseplants, but TBH one of the most rewarding we’ve experienced is nursing a dying plant back to health. We’ve been in the care of plants on their absolute last legs - down to just one or two sad leaves or even no leaves - and then, with a little TLC (and a lot of neem oil) that plant rises from the ashes to reclaim their former glory! And…well, no, you won’t be able to convince us that we’re exaggerating.

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