One of the first signs of an unhappy Anthurium is a change in the color of its leaves. When you notice the foliage changing from its normal vivid green to yellow or brown, it often means that something is off with the plant or its growing conditions – but what exactly is wrong? How can you tell what’s causing the discoloration in your Anthurium’s leaves?
Direct sunlight can scorch Anthuriums, making their leaves fade or turn brown. Watering issues may also lead to discoloration. Dry soil and crispy, shriveled leaves typically indicate a thirsty plant; damp soil plus yellowing or brown-edged leaves are signs of overwatering. And even properly watered Anthuriums can develop brown leaf tips if the air isn’t humid enough for their tropical tastes.
If you fertilize your Anthurium and you’ve had it in the same pot for a while, the discolored leaves could also be the result of salts building up in the soil. And there are a number of insect pests and bacterial infections that attack Anthurium leaves. This article will explain how you can identify which of these issues is affecting your plant – and what you can do about it.
Keeping Anthurium Leaves Green
Before we dive into all the ways that Anthurium care can go wrong, we should make sure we understand how to get it right. What conditions make for a thriving Flamingo Flower?
The right environment will be similar to an Anthurium’s natural habitat: the lush rainforest canopies of Central and South America. Most of the Anthurium varieties you can get from houseplant retailers are epiphytes – plants that attach themselves to other plants for support. They like to climb well above the ground, though not so high that they peek out above the treetops.
Unless you’re an eccentric billionaire, you probably can’t create a miniature jungle inside your house. Instead, you’ll have to try to simulate the lifestyle your Anthurium is used to. That means providing:
- Bright but filtered sunlight. Despite living in the shade of bigger plants, Anthuriums in the wild get a lot of sun, but most of it reaches them after bouncing off other surfaces or filtering through the leaves of trees. Keep your plant in a room that gets plenty of light, in a spot where the sun’s rays won’t fall directly on it.
- A coarse, airy, soilless potting mix. Anthurium roots are built to absorb water from the air or from the loose moss and leaf litter that accumulates in the nooks and crannies of trees. Ordinary potting mix or garden soil can get too wet and clingy, preventing your plant’s roots from breathing.
- Moist air. High humidity is another feature of the rainforest that can be hard to replicate in your home; most of us don’t enjoy the swampy air that Anthuriums love. Indoor gardeners usually compromise by using a small humidifier or misting the plant’s leaves frequently with a spray bottle.
- Warmth. Again, these are tropical plants, and they like tropical temperatures. Their ideal range is between 65 and 85 degrees, with a little bit of wiggle room – as long as it doesn’t get below 55 or above 90, your Anthurium should be okay.
- Frequent, weak doses of fertilizer. Anthuriums in natural settings get their nutrients from rainwater and the decaying scraps of other plants. Liquid fertilizer diluted to ¼ strength, included with your Anthurium’s water in the spring and summer, should provide the small trickle of nutrition that it needs.
What Causes Leaf Discoloration?
Getting any of the factors listed above wrong can either cause leaf discoloration directly or weaken the plant so that pests and infections can gain a foothold. Let’s talk about what those problems look like.
Too Much Sun
The rays of the sun are too hot for your Anthurium to handle, especially as it climbs higher in the sky and the intensity of the light increases. More than a couple of hours of full sun will dry out the surface of the leaves, causing them to take on a faded or scorched appearance. Mild cases of sunburn will turn the surface yellow, while severe cases will produce brown, dead tissue.
Unlike many leaf problems, sunburn usually won’t cause discoloration on any particular part of the leaf – it’ll appear anywhere that too much light has fallen. If only one side of the plant is facing the sun, and that’s the side where all the discoloration is focused, it’s pretty easy to make a diagnosis of sunburn.
Dealing With Sunburn in Anthuriums
When you see brown or yellow patches on Anthurium leaves, and you know the plant has been in direct sunlight, your first step should be to move it to a shadier spot. Don’t overreact by shutting it away from light entirely, though; it still needs to photosynthesize to survive. Instead, find an area that’s in a well-lit room but away from actual sunbeams.
If you have to pick a window spot for your Anthurium, try to choose an east-facing one that only gets a few hours of mild early-morning sun. Putting up sheer curtains to filter the light before it hits your Anthurium can also help.
Too Much Water
Overwatering is one of the easiest errors for an Anthurium owner to make. No one wants to feel like they’re depriving their plant of life-giving water; so many people overcompensate and provide way too much. The problem is that plants actually need some air in the soil to let their roots breathe, and they’ll start to suffocate when the pot is full of standing water or murky soil.
If the swampy conditions in the soil persist long enough, bacteria and fungi can begin to multiply rapidly and attack your Anthurium’s roots. This condition is known as root rot, and it’s lethal to your plant if it goes unchecked.
Anthuriums are especially vulnerable to overwatering because they’re adapted for an aerial environment that offers even more breathing room than most plants get. And their fleshy roots are tempting targets for the organisms that cause root rot.
If your Anthurium’s leaves are yellowing and drooping all over, rather than in patches or at the tips and edges, it’s often an early sign of overwatering. That is especially true if you notice that the soil is still damp, and if the leaves feel fleshy or limp rather than crispy.
Brown, mushy spots on the leaves (or at the bases of the stems) are more concerning; they can be signs of advanced root rot that has spread up to the foliage. A musty or sour smell coming from the potting mix can also mean there’s rot under the surface.
Dealing With Overwatering in Anthuriums
If the problem is still in its early stages, you may be able to solve it by simply slowing down your watering schedule. Always wait until the upper layer of the potting mix has dried out before giving your Anthurium any more to drink.
Check the moisture level every 1-2 weeks with your finger or a moisture meter. Water only when it’s dry to the depth of your second knuckle or so, or when the reading on the meter is at the low end of “damp.”
Root rot, on the other hand, requires more drastic measures. You’ll need to remove the Anthurium from its pot, clear away all the soil, and trim back any roots that show signs of infection. You can recognize rotting roots by their black or gray color, or by their mushy, slimy feel. Healthy Anthurium roots should be white with a firm texture.
Use a sharp pair of shears or pruning scissors, sterilizing the blades between cuts. Good disinfectants include isopropyl alcohol or bleach diluted to 10% strength. It’s also a good idea to wear gloves, since the fluids of Anthuriums can be irritating to human skin. Be merciless with your trimming – any roots that are “questionable” should be discarded.
Repot the Anthurium in all-new potting mix. The old stuff is contaminated with rot, and you should throw it out. To reduce the risk of overwatering in the future, use a loose, breathable mix and a pot with a drainage hole. You can find more detail in our article on soil and containers for Anthuriums.
Too Little Water
Underwatering can also affect the color of your Anthurium’s leaves. As with overwatering, mild cases usually cause yellowing and wilting, while more severe cases can cause leaves to turn brown and die.
The reason these conditions can appear so similar is that they both prevent the plant from taking up enough water. With overwatering, the roots are smothered and potentially infected, while in underwatering, there’s nothing for them to drink. Either way, your Anthurium’s foliage is under stress from dehydration.
To tell the two issues apart, start by looking at the potting mix. If it’s dry and caked, pulling back from the edges of the pot, you’re probably dealing with underwatering. The foliage may also shrivel and curl, taking on a dry and crispy texture like fallen leaves in autumn.
Dealing With Underwatering in Anthuriums
You may want to sit down for this one. The cure for underwatering is…Water.
Okay, that’s not exactly an earth-shattering revelation. But Anthurium owners who are aware of the dangers of root rot sometimes get too timid about watering their plants. With a container and potting mix that provide good drainage, it should be fairly easy to keep from drowning your Flamingo Flower.
Underwatering is most likely in the summer months. The heat speeds up evaporation, and your Anthurium is busy creating new growth, so its need for water is greater. Check the soil for dryness every week during the warmer months to ensure you’re not letting the plant go too long without a drink.
Keep in mind that the material of the pot also affects the need for water. Terra cotta pots are porous, allowing moisture to escape faster by evaporating right through the sides. If your Anthurium is planted in an unbaked clay vessel, it will probably need more frequent watering. As always, the best strategy is to monitor the potting mix.
When it comes time to water your Anthurium, give it a good soak. Pour until you see water emerging from the drainage hole at the base. You want to ensure that you’ve gotten the entire root system good and damp.
If the soil has been dry for too long, the water will run right through the mix and out the bottom immediately. In that case, wait about thirty minutes and add a second dose of water.
Humidity is another important issue for Anthuriums. The air in your home doesn’t have to be quite as steamy as a rainforest for your Flamingo Flower to survive, but if the humidity level drops below 50 percent, you’ll often see the leaf tips turn brown.
This is most common during the winter when home heating systems produce a lot of hot and dry air. You can keep track of the humidity in your plant’s room using an inexpensive hygrometer, giving you some advance warning before the leaves begin drying out.
Dealing With Humidity Issues in Anthuriums
There are a few things you can do to boost the humidity around your Anthuriums. The most effective method is to use a humidifier (we have some recommendations here) to automate the process.
For a cheaper but higher-maintenance option, you can mist an Anthurium regularly with a spray bottle. Use lukewarm water to avoid stressing the plant, and set the spray as fine as possible to ensure that it dries quickly. If water pools up and remains on the leaves for too long, it can give bacteria and fungi an opening to colonize the plant.
Unlike watering, it’s hard to overdo it with spritzing. As long as the leaves dry off between applications, you can mist your Anthurium every day – in fact, this may be necessary for really dry climates.
Another trick is to use a humidity tray. Fill a shallow, flat-bottomed dish with pebbles, marbles, beads, or something similar. Then add some water to the base, and set your Anthurium’s pot on top. The water evaporating from the dish will add a little bit more humidity to the plant’s immediate surroundings, while the beads keep the roots from sitting right in the water.
Pebble trays aren’t as effective as misting or humidifiers, but they can help if you’re pretty close to your target humidity and just need a little extra push. Note: try to make the pebbles or beads fairly uniform in size; after all, the plant’s container needs to balance on top of them.
Mineral Salt Buildup
Discoloration could also be caused by an excess of mineral salts in the potting mix. As concentrations of these chemicals get too high, they interfere with the uptake of nutrients and water into the roots. In extreme cases, the salt deposits can actually suck water out of your Anthurium by osmosis.
Leaves that are yellowing and browning around the edges can indicate salt burn. Other signs include a whitish crust appearing on top of the potting mix or irregular patches of translucent white on the leaves. If you’re fairly sure that watering and humidity issues aren’t causing the discoloration in your Anthurium, then salt buildup could be the issue – especially if the plant has been in the same pot for a while.
There are two main causes of mineral accumulation. The first is fertilizer. Most important plant nutrients are absorbed in the form of soluble salts, and anything your Anthurium doesn’t use will remain in the soil. In nature, this excess is washed away by rain, but in a closed container, there’s almost always some accumulation over time.
The other cause is giving your Anthurium tap water. Municipal drinking water often contains high concentrations of minerals like magnesium and calcium. That’s why many houseplant owners prefer to use rainwater or distilled water for their indoor gardens. A quick online search can usually tell you if your local tap water is “hard,” meaning it has a high mineral content.
Dealing With Salt Buildup in Anthuriums
The usual way to handle mineral salts in plant containers is to flush them out regularly with water. Place the pot in your sink or shower, or outdoors near a hose. Then run a gentle stream of lukewarm water over the leaves and into the soil, allowing it to drain out of the base.
Keep going until you’ve passed enough water through the container to fill it up four times. This will wash most of the minerals out of the potting mix, and your plant should be looking greener again within a few days.
If you fertilize your Anthurium, or water it from the tap, you should flush it every 3 or 4 months to keep the salt levels in check.
Excessive Heat or Cold
Temperature is another possible culprit when your Anthurium’s leaves shift colors. When the plant is too cold (below 55 degrees Fahrenheit) for prolonged periods, its leaves may turn a pale yellow and could even start falling off. A sudden shock of extreme cold can cause brown edges or pale spotting.
Anthuriums that get too hot (above 90 degrees) will dry out and display the symptoms of low humidity we outlined above.
Dealing With Temperature Issues in Anthuriums
The fix here is simple: get your Anthurium back into the temperature range it prefers. The plant should bounce back once its growing conditions return to normal.
Insects or Mites
Miniscule pests can lead to big problems for houseplants. Anthuriums are especially susceptible to sap-sucking critters like mealybugs and spider mites.
These attackers can drain the moisture out of your Anthurium’s leaves, producing yellow and brown spots that can look somewhat like dehydration. However, these marks are often smaller and more irregular in appearance, popping up in seemingly random patches and clusters all over the affected leaves.
Aphids and scale insects also produce a sticky substance called honeydew that can serve as a breeding ground for sooty mold. If a dark, powdery coating appears on your Anthurium’s leaves, it’s often a hint that you have a bug problem.
Our article on Anthurium pests can help you identify whether your discolored leaves are the result of an infestation.
Dealing With Anthurium Pests
When you suspect insects are after your Anthurium, the first step is to isolate it from any other plants you have. These pests can spread quickly, so quarantine your Patient Zero as soon as possible.
Next, spray the foliage vigorously with a shower or garden hose to knock off as many bugs as you can. Then spray it thoroughly with watered-down liquid soap. Use about a teaspoon of soap per liter of lukewarm water, shaking thoroughly before and during the spritzing process. Avoid any soap with harsh chemical additives like degreasers. Wait a few minutes and rinse it off again with water.
For some extra stopping power, you can add some neem oil to the soapy water solution. In this case, the recipe is ⅓ of a teaspoon of soap, 1 teaspoon of neem oil, and 1 liter of water. You might also want to swab your Anthurium with cotton pads dipped in rubbing alcohol, particularly if you have scale or mealybugs.
You’ll probably have to repeat this treatment several times to entirely stamp out your pest issue. Bugs can be quite determined when they find a plant they really like. Our pest article has more detailed advice on specific insects and on dealing with really stubborn infestations.
Bacterial infection can also mess up the color of Anthurium leaves. Leaf blight is a nasty disease that spreads from other infected plants when growers fail to disinfect their pruning tools after using them. Sloppy technique when trimming or taking cuttings can also leave ragged wounds that allow bacteria inside. And pests can transfer bacteria when they bite into the plant.
Leaf blight causes small yellow and brown spots that grow and spread to cover the leaves, usually starting at the edges and moving in. These spots typically have a dead, pitted area in the middle and a yellowing ring around that, with smaller spots forming nearby. As they spread, they may form a characteristic V shape on the leaf.
Dealing With Leaf Blight in Anthuriums
Once again, you should quarantine your Anthurium to prevent it from infecting your other houseplants. Then you need to amputate. Break off any infected leaves a little way down the petioles (the slender stem that connects the leaf to the main stalk) and burn them. There’s no way to treat infected tissue, so the only solution is to remove it all.
If the disease spreads to the vascular system, the plant is sadly beyond saving and will have to be discarded. To tell whether that’s the case, cut off the petiole of one of your Anthurium’s older leaves and look at the sliced end. Lots of tiny dark spots inside means that the bacteria have colonized the tiny channels that carry water and nutrients throughout the plant – in other words, your Anthurium is doomed.
Anthurium Leaf Aging and Pruning
This article wouldn’t be complete if we didn’t mention that Anthurium leaves do eventually lose their color and drop away over time, even if nothing is wrong with the plant. If you see one or two older leaves growing pale and withered, it’s probably not a problem.
It can still be helpful to pinch or snip those dying leaves off when you notice them. Even a leaf near the end of its life is drawing some energy from the plant for maintenance. When you remove it, your Anthurium can devote those resources to new growth and flowering instead.
Take the dead leaves off as close as possible to the junction between petiole and stalk, pinching them between your fingernails or snipping them with shears. As we advised earlier, wear gloves, and disinfect your tools periodically while you work.
Trimming Damaged Anthurium Leaves
What about when leaves are unnaturally discolored? Should you snip them off when they show signs of sunburn or dehydration, or salt buildup? The answer is a little complicated, but it boils down to: maybe, but not right away.
Once you fix whatever is out of whack with your Anthurium’s growing conditions, you should wait for it to begin producing healthy new leaves before you prune the distressed ones. Unless the entire surface has been damaged, each leaf is still contributing some energy from photosynthesis. Removing leaves that are healthy except for a few discolored spots will slow the Anthurium’s recovery.
You can trim off the damaged leaves once you’re sure the plant is bouncing back. Even then, it’s fine to let them stay if they only have minor discoloration.
Obviously, there’s a huge exception in the case of an infection or infestation that can spread to healthy tissue. Speed is essential in that scenario. If you think your Anthurium’s leaves are affected by rot, ravaged by leaf blight, or loaded down with parasites, prune them right away.
Leaf discoloration in Anthurium leaves can result from a wide range of problems. Identifying the true cause will require careful attention to your care regimen and the plant’s environment. Hopefully, the pointers in this article will help you spot what’s distressing your Anthurium and get it back on its feet.