The snake plant, much like the ZZ plant, has a reputation for being difficult to kill. Difficult doesn’t mean impossible though. If your snake plant has begun displaying brown spots on its leaves, this is a sign something in its care routine isn’t right. What causes these brown spots?
Why does my snake plant have brown spots? Snake plants can develop brown spots for the following reasons:
- Fungal disease
- Pest infestation
- Too much fertilizer
- Lack of humidity
- Cold stress
- Harsh sunlight
- Chlorine in the water
Yes, just like my post about peace lily leaves browning, your snake plant leaves can turn brown for a whole myriad of reasons. In this extensive post, I’ll cover all 9 causes of snake plant brown spots in detail. I’ll also have an entire section of remedies for the brown spots on the leaves of your snake plant. So keep reading!
Brown Spots on Your Snake Plant? Here Are the Causes
Snake plants are especially susceptible to fungal diseases as their lengthy, slender leaves can retain moisture longer than some other indoor plant species. All it takes is altering the plant’s watering habits a little bit and voila, you’ve introduced a fungal disease to your snake plant, and often unknowingly at that.
Three fungal diseases are common targets of the snake plant: red leaf spot, southern blight, and rust.
- red leaf spot
- southern blight
Also referred to as Helminthosporium disease, red leaf spot isn’t just one fungal disease, but a complex of them. Caused by Helminthosporium pathogens that thrive in wet and warm conditions, plants with red leaf spot will have sizable spores often shaped like cigars. As the name of this fungal disease suggests, the spots will be red or brownish-red.
Southern blight–which is also known as southern root rot or southern wilt–starts in the soil. There, a fungus species called the Sclerotium rolfsii invades underneath the soil line or just at that line. Like the fungus that causes red leaf spot, the Sclerotium rolfsii prefers warm weather or warm environments.
Your snake plant might look droopy if it has southern blight, with leaves that start yellow but can become a light brown without treatment. The entire plant will soon collapse and eventually die as the fungus wraps around the roots and infiltrates the entirety of your snake plant’s soil.
The third fungal disease to be on the lookout for is rust. No, I’m not talking rust like what happens when metal is exposed to water for too long.
Rust or Phragmidium is a type of fungal disease that’s most common in lawns, tomatoes, beans, daylilies, and snapdragons but can affect the snake plant as well.
Rust happens more often in matured plants, but not always. Early on, the fungal disease may manifest in raised white areas near the snake plant’s stems and underneath its leaves. The white spots soon turn orange-brown and later black as the infestation progresses and the plant dies.
Just as detrimental to the health of your snake plant is an infestation of pests. Several species of insects prefer the snake plant over other house plant species. These are spider mites and mealybugs.
Spider mites are Tetranychidae family members with more than 1,200 different species. They prefer to nestle beneath a plant’s leaves.
Given the size of a snake plant’s leaves, this is the perfect spot for spider mites to live. Since an average spider mite is 0.04 inches, many of them can gather on the snake plant at a time.
How Can I tell if it’s a Spider Mite Infestation?
First, spider mites will make a web underneath your snake plant’s leaves. Once they’re all settled in, they eat into the cells of your snake plant and suck out the sap inside. Any spot where the spider mites choose to munch can create brown spots in the mite’s wake.
Aside from the obvious chew holes in the leaves of your snake plant that are outlined in brown, the second easiest way to tell it’s the spider mites is by looking closely at the backside of the leaves for their webs.
How Can I tell if it’s a Mealybug Infestation?
Mealybugs are the other enemy of the snake plant. As Pseudococcidae family members, mealybugs are scale insects without armor that prefer warm spaces.
They too will gladly suck up all the juices in your snake plant as well as those in some other houseplants, so be careful. Again, telltale brown spots will indicate a problem with mealybugs.
The other big issue with mealybugs is they can lead to the development of diseases that could kill your snake plant.
Overdoing It on the Fertilizer
One area that can trip you up when starting an indoor garden is fertilizing your houseplants. As I discussed in my article regarding fertilizing the peace lily to instigate blooming, it doesn’t need fertilizer much, but other plant species do.
The snake plant is one of those houseplants that leans more towards sparse fertilizing. You want to wait for the weather to get hot, not necessarily for the growing season to begin, and then fertilize.
Even still, you might fertilize your snake plant once during the summer and that should suffice. Refrain from fertilizing again in the fall and the winter, as the snake plant isn’t as active then so it doesn’t need the nutrients.
Some indoor gardeners even get by with healthy snake plants by never fertilizing them. If that’s the route you take, you need to ensure you’re at least giving your snake plant either a compost full of nutrients or plant food.
If you happen to use too much Miracle Grow plant food, I’ve got the perfect article for you: How to Fix Using Too Much Miracle-Gro on Your Plants
You can use a standard all-purpose plant fertilizer for your snake plant, even better, an organic mix if plant fertilizer is your preference.
Lack of Humidity
The snake plant isn’t particularly needy about how much humidity it gets, as it requires about 40 percent relative humidity. It just so happens that humidity at this level is recommended for us people as well because it’s very comfortable.
You’re not sweating in 40 percent relative humidity, and the air is moist enough that your nasal passages and lips aren’t drying out and your skin isn’t itchy and uncomfortable.
Remember, the snake plant tends to maintain moisture on its long leaves. You’re not the only one to feel dry when your home or office isn’t at least somewhat humid. The snake plant’s leaves will also dry out, and without water, those leaves will likely become brittle and brown.
If you’re not sure how humid your home is (as most thermostats don’t tell you), a hygrometer will let you know. The ThermoPro on Amazon is a digital hygrometer that runs on AAA batteries.
The ThermoPro will indicate the current humidity levels as well as record low and high humidity. It’s actually the newer version of the one I’ve been using for a few years now and it’s saved more than a few of my plants from their demize, especially in the middle of summer and winter.
If you missed it, I recommend you check out my article on ways to add humidity to a home or office for your houseplants. You’ll find lots of smart, inexpensive ways of boosting the humidity for not only your snake plant but any houseplant in your indoor garden that requires it!
The moisture in the air is one thing and the temperature is another. Snake plants aren’t super particular here either, at least to a point. Even if the temperatures dwindle to 41 degrees Fahrenheit, your plant won’t out and out die, but it is more likely to suffer cold stress.
What is cold stress?
Occurring from exposure to very chilly temperatures, cold stress causes the water within a cell’s wall to freeze. Since water expands when it becomes ice, the same happens to the plant wall, putting immense pressure on the membrane. Some membranes will rupture. If enough do, the cell will die.
Long before cell death, your snake plant’s leaves will begin exhibiting brown spots, typically in the areas where the cells are already under great duress. Fortunately, you don’t have to bump your thermostat far to get into a comfortable range for the snake plant.
By day, this plant prefers temperatures of 60 to 80 degrees. At night, drop the thermostat between 55 and 70 degrees.
Too Much Direct Sun
If you’re a long-time reader of this blog, then you’ve probably seen the snake plant mentioned on my list of plants that can tolerate low light, such as the Best Tall Indoor Plants for Low Light article.
Indeed, it’s true that the snake plant will live if the lighting conditions at home or in the office aren’t ideal. The plant might not grow that much, but it won’t wither and die either.
Snake plants are even tolerable of full sunlight, but their favorite conditions are indirect light. As often as you can, you want to make sure you can provide that kind of lighting. Otherwise, you could be accidentally setting up your snake plant to develop brown spots on its leaves.
Why is that? The snake plant gets used to whatever lighting it’s growing in, especially if it’s been in the same conditions for a while. So let’s say your snake plant has always grown in a dim room, such as your cubicle at work.
One day, you decide to bring the snake plant home and put it in your bright living room, where it’s now getting full sun.
Going from one extreme to the other is harder for your snake plant to acclimate to. It might get stressed and show brown leaves, especially at the tips.
You don’t much like being in a dark bedroom and then having someone pull back the curtain to reveal the full brunt of the sun. Your snake plant is the same way. If you must take it from a dimmer to a brighter environment or even vice-versa, acclimate the plant incrementally to make the shift less shocking.
Chlorine in the Water
Your swimming pool isn’t the only source of water that has chlorine in it. Chlorine also goes into most public water supplies due to its status as a disinfect. By dumping in chlorine, public water is rid of protozoans, viruses, bacteria, and pathogens, all of which can cause diseases.
If you drink and bathe in tap water, then that water more than likely has chlorine as well. The Environmental Protection Agency or EPA does limit how much chlorine is allowed in potable tap water, with 4 parts per million (ppm) the limit, says this Water Quality & Health Council piece.
Consuming that much chlorine should not cause any adverse health effects, notes the EPA. The Water Quality & Health Council piece also states that most water supply systems in the US, up to 98 percent of them, rely on chlorine for disinfecting, so it’s pretty common to have chlorine in your tap water.
That’s all fine and good for you and your family, but not so much for your snake plant. Watering your snake plant with chlorinated water could make its leaves turn brown.
Your snake plant will accept a lot from you as an indoor gardener. Don’t fertilize it for a year? No biggie. Leave it in the dark? That’s okay. However, when it comes to watering or not watering the snake plant, it’s a lot less acquiescent to its conditions.
Since snake plant leaves are already somewhat moist more often than not, when you overwater the plant, the leaves will be the first to show the side effects. The leaves will first begin to drop as the plant retains too much water.
Next, blisters might appear on the surface of the leaves. Your snake plant is now a target for the fungal diseases I discussed earlier in this guide.
The bloated leaves will also look brown in areas due to nutrient deficiencies, but you should be more concerned with what’s going on under the surface. The snake plant’s usually strong white roots have become weak and mushy as the water oversaturates them. Once the roots turn black, they’re dying or soon will.
The snake plant can go anywhere from two weeks to two months without being watered, which is a huge discrepancy. You might accidentally forget to water your snake plant or water it sporadically, as it’s been so long since you’ve last done it.
The snake plant is no succulent, yet it’s able to live for about six weeks without water before it begins dying due to its ability to store water quite well. Yet when the plant goes without water for weeks and suddenly has an influx, or if only gets a bit of water, bad things happen.
Underwatering your snake plant will leave it dehydrated, with the leaf tips dry, crispy, and brown. This may affect the whole plant if you don’t water it consistently going forward.
How Do I Get Rid of Brown Spots on My Snake Plant?
Discovering brown spots on the leaves of your snake plant is quite concerning, as it rightfully should be. These spots are a signal that you need to start better prioritizing your snake plant’s care.
Here’s how to get rid of the spots so your snake plant looks and feels healthy once more.
Treat Plant Diseases
Whether it’s rust, red leaf spot, or southern blight, when your snake plant has a fungal disease, quick remediation is crucial. The disease can and will spread, eventually killing your beloved snake plant.
To tackle red leaf spot, every two weeks or so, you want to use a fungicide on the affected area. If you’re concerned about hurting your snake plant and the surrounding plants in your indoor garden with chemicals, you can make a DIY chemical-free fungicide at home.
Two Ways to Make DIY Fungicide for Your Snake Plant
- Start by combining bleach and dishwashing detergent. Make sure the detergent has no degreasing ingredients, and always wear gloves when handling bleach.
- You can also mix water (a gallon) with baking soda (4 teaspoons) or potassium bicarbonate in the same quantity.
Sterilize your Potting Soil to Combat Southern Blight
If it’s southern blight that has afflicted your snake plant, you can heat-treat the soil, using a heat mat that’s set to 160 degrees or even 180 degrees. Let the soil sit for a half-hour at that temperature, then turn the heat mat off.
You want to take the soil out and separate it from any healthy soil in your snake plant’s pot. Should heat-treating not work, I’d suggest just replacing the soil.
What about plant rust? Remove any leaves with brown spots from rust, disinfecting your gardening shears before and after you’re finished. The homemade DIY fungicides I listed above will work just as well for treating snake plant rust.
Rid Your Snake Plant of Pests
If your issue with your snake plant isn’t a fungal disease but rather a pest infestation, here’s what you should do.
For spider mites, start by removing any affected parts of your snake plant with brown spots or spider mite webs. Next, use a garden-safe insecticide like neem oil or horticultural soap.
For mealybugs, grab a cotton swab, cover it in isopropyl rubbing alcohol, and apply the swab directly on the bug. Isopropyl alcohol is just rubbing alcohol, so you might already have some in your bathroom. Do make sure the stuff has a solution of 70 percent alcohol for the best results.
I’d also suggest you avoid getting isopropyl alcohol on your snake plant as much as you can when removing mealybugs this way. Too much isopropyl alcohol could lead to leaf burn!
Water the Snake Plant with Distilled Water or Rainwater
If it’s chlorinated water that has wrecked your snake plant’s natural leaf coloration, then switch to distilled water or rainwater, as neither has chlorine.
If you have some time and patience, you could always let the chlorine and other fluorides in your tap water dissipate naturally. This is what I do from time to time.
I will fill a three gallon container with tap water and let it sit over the weekend and by Monday morning I have fresh clean water for a good portion of my plants. Allowing the water out of your sink to dissipate naturally will happen in about 48 hours.
Just remember to let the water stand, at least, that long. Then you’re free to give it to your snake plant without the worry of chlorine or fluoride damaging your plant.
Get into a Good Watering Schedule
If you don’t water your snake plant often enough, I’d advise you to start checking on the plant at least once a week. You don’t have to water it that frequently, but putting your fingers in the soil to see how moist or dry it is will be great indicator for when it’s next time to rewater.
If you water your snake plant too often, follow that above soil test rule, as it’s pretty foolproof. You want the soil of your snake plant to feel completely dry. Then you can grab your watering can.
Make Sure You Have a Pot with Drainage Holes
It might not even be how often or seldom you water your snake plant that’s the issue, but rather, the pot you’re growing the plant in. If your pot doesn’t have drainage holes, that’s a huge problem.
The water you give your snake plant has nowhere to travel, so it pools up at the bottom, soaking the roots and leading to root rot.
Filling the bottom of your snake plant’s pot with stones or rocks is a poor idea as well, as the rocks block up the drainage holes, again making your plant likely to get root rot.
Snake plants don’t need a lot of care, but throwing too much caution to the wind can lead to the development of brown spots. Now that you know which areas you may have misaddressed when it comes to your snake plant, you can begin treating yours better so it grows and thrives!