15 Common Problems With Coleus Plants

Coleus are extremely versatile plants that can be grown in many different environments. They can be grown in gardens, containers, and even be brought indoors as houseplants. With propagation, one plant can make many coleus plants, which adds to their charm.

Coleus comes in so many unique and interesting varieties. There are many different colors, shapes, and sizes of foliage to choose from. Once you welcome your first coleus into your garden, don’t be surprised if you find yourself picking up new varieties to add to your collection.

Sometimes coleus can start to suffer or fail. When this happens, they will often show many signs of struggle. It’s important to be able to identify those symptoms and treat them early on. Let’s look at some of the most common coleus problems you are likely to run into.

Drooping Leaves

This is one of the most common problems with coleus. The leaves are hanging down and look really sad and droopy.  There are a few reasons this could be happening.

The most common reasons are going to be water or too much sunlight. They are real divas when it comes to water, and most varieties can’t handle too much sun. If they are dry and need a drink they will tell you. As soon as you give them water they will begin to rise from the dead and perk back up.

If you see a droopy plant, don’t wait and water them as soon as possible, and adjust their lighting conditions where possible. It doesn’t take long for them to go from droopy to the crispy point of no return. It’s amazing to see how fast they perk up after getting a drink.

Another reason they could be droopy is the exact opposite of the first reason. The plant could be over-watered. Luckily this is easy to distinguish. Just stick your finger into the soil and test if it is dry or wet.

They do not like sitting in standing water or being in wet soggy soil. If the soil is really soggy you will need to correct this. Using proper potting soil in containers, having drainage holes in containers, and amending beds with coir or peat will help water absorb and drain freely.

Avoid planting coleus in any low-lying wet or boggy areas in the garden. They will droop and eventually die. If your plants are over water immediately stop watering and let them dry out if you can.

Color Problems

The color of their foliage is a coleus plant’s best feature. When this isn’t going the way you planned, it is disappointing. Their color comes down to sun exposure.

In too little sun, the leaves will appear dull. They might take on a flimsy and thin quality. The more vibrant red and pink color will fade to more greens and yellows. I find this particularly a problem when they are in a darker area of the house.  Move them into a sunnier location and the color will brighten.

On the flip side, if you have a coleus in more sun it will have more intense reds and pinks. In very intense sun you may end up with all red and pink colored leaves with a little variation into white, yellow, or green. It’s important to remember that certain varieties do better in the sun than others.

Brown, Black, or Rotten Stems

I find this is a common coleus problem with many gardeners: stems that just turn brown, then black, and then fall off. To prevent stem and crown rot, keep the soil light and evenly moist. If you have heavy soil full of clay the stems will be continuously wet and will rot.

Test your soil by squeezing a handful of it. If it stays in the form of a ball like putty, you have clay soil. If you do have clay soil, amend it with coconut coir or peat to make it lighter.

For container-grown coleus, use potting mix (not garden soil). Even amended garden soil is not light enough for a container environment. Also, make sure your pots have adequate drainage so that extra water can drain out the bottom.

If the stems are rotting, consider taking cuttings and rooting those to start the plant over again. Even a small cutting will produce a new plant. Trim off new growth, not the older woody stems, to propagate them.

Leaves With Brown Tips

Brown tips are one of the coleus problems you would find in indoor plants. This is often because of a lack of humidity. Try placing a small tray of pebbles filled with water underneath your plant to add extra humidity. Or, run a small humidifier nearby.

Don’t leave your indoor plants near heat vents. The hot air will cause the leaves to turn brown.

Another cause of brown tips in outdoor plants is cool temperatures. Coleus do not like temperatures below 50°F (10°C). If they are exposed to temperatures lower than 50°F they will get brown tips and eventually die if exposed for long. Keep an eye on night temperatures especially.

Sudden Plant Death

This is the worst—your new coleus just dies. There’s no saving it. It goes limp and then dissolves. While this isn’t a problem you can readily fix, you can avoid doing the same thing over and over again.

Sudden death is usually because the soil or the night temperatures are not warm enough. Keep a close eye on the weather if you live in a cooler area. Planting coleus too early will kill them.

Make sure the night temperatures are consistently above 50°F (10°C) before bringing them outdoors. Also, make sure that the soil temperature is over 60°F (16°C) before planting them in the ground. Coleus do not rebound from getting cold. They simply go limp and die.

If it is nearing the end of the season, keep a close eye on frost. They can not take the lightest kiss of frost. Bring in any plants you wish to save before the night temperatures start to fall.

Holes in Leaves

Holes in your coleus are a sign of slugs. Unfortunately both slugs and coleus like damp and shady areas. If you notice holes in the leaves, and can see the little slimeballs nearby, it’s time to take action.

Placing trays of beer out for slugs to drink and then throwing them out is another method people often use. I personally think it’s overrated. You’re constantly replacing beer trays and dumping slugs. Lots of work with little reward. But some people swear by it, so it might be worth a try.

My favorite method to control these coleus problems is to purchase slug bait from the garden center. It’s little pellets that the slugs eat and then go and die. I sprinkle it in my gardens and containers and they seem to disappear.

Stunted Growth

Coleus that just don’t seem to grow and remain the same size are probably not planted in their ideal conditions.

I discussed how heavy clay soil can kill a coleus (it will stunt growth and then it might die off from there). Soil without nutrients will also stunt growth. Mix compost, worm castings, or manure in with the peat or coir when amending garden soil. This will help coleus grow large and healthy.

If the soil temperature is too cold it will also stunt growth. Make sure the night temperatures are consistently above 50°F (10°C) before planting them.

Growing Up and Not Out

If you see your plants keep growing up and up, but you want them to grow bigger and bushier, you will need to prune.

Coleus leaves will sprout two new shoots for every stem you cut. If you have a large single-stemmed plant, you can keep it growing that way no problem. But if you want it to get bushier, you will need to cut it.

It might not look as nice at first, but soon the two new sprouts will come out for the cut stem. Let those grow up and prune them and two more will sprout and on and on. If you are familiar with pinching basil, it is the same thing.

Big Leaves Dying Out

This is just part of coleus growth. Some of the big leaves will die off. Pick them off and look at the smaller new leaves waiting to emerge.

This is not really one of the major coleus problems but can be concerning. Picking yellowing leaves is part of regular maintenance. Fertilize every two weeks with an all-purpose fertilizer to keep your coleus growing.

Leaves With Brown Lesions

Brown lesions and/or irregular brown spots on coleus leaves are a sign of downy mildew. Unfortunately, downy mildew thrives in hot wet conditions, as do coleus.

If you notice these irregular brown spots and the leaves, especially the lower leaves, it might be downy mildew. Other signs include a fuzzy growth on the underside of the leaves that may have a purple hue.

The best method is to create less humid conditions. This might not be possible in the garden. But containers may be moved to drier, sunnier locations. Also, try and water your coleus in the morning as opposed to the evening so that the leaves can dry off right away.

If it does get past the point you can control, there are fungicides on the market that can help. Make sure they are suitable for downy mildew, which is not interchangeable with powdery mildew.

Bleached Leaves

Bleached leaves are a sign that your coleus is in too much sun. There are new varieties on the market that take full sun. Take a look at the Colorblaze series, as they can take sun and shade. But for many varieties, shade is the best place.

If you notice the leaves appear to be bleached or crispy, it is likely sunscald. This means the coleus is in too much sun. Even the sun-friendly varieties can get this if they are placed in the blazing hot sun.

Plant in areas that receive morning sun. Or under a tree where it will receive dappled shade. Try and protect your coleus from the heat of the afternoon sun. If you are planting your coleus in more sun, make sure you are providing them with more water.

Problems With Rooting

I love starting new plants from cuttings. If you are having problems successfully rooting cuttings, there are a few things to consider.

Coleus cuttings root very easily. Make sure you take a soft plant cutting. The older stems of coleus will become woody. These are not ideal to root. The new soft green growth is where you want to snip or pinch off from.

Coleus cuttings will root in a glass of water or vase indefinitely. If you’ve left them in water and the roots have grown huge they will be harder to transition into the soil. If you want to grow cuttings in soil, get them to root in soil as soon as possible.

Get evenly moist seed starting mix or potting soil and dip the cutting in a rooting hormone (optional), then place it in the soil. Cover the cutting with a dome lid or plastic bag and keep out of direct sunlight until it starts to root.

Mealybug Infestation

Mealybugs can affect a wide variety of plants, indoors and out. You can identify them on your coleus as fuzzy little white bugs. They also create a substance called honeydew which will be found on the leaves of your plants. Black mold will start growing on the honeydew.

Soak cotton balls in rubbing alcohol and rub the mealybugs with it. Or you can use an insecticidal soap. The honeydew can be wiped off with a soft damp cloth.

Spider Mite Infestation

If you notice your coleus foliage looking mottled and, upon closer inspection, a fine webbing covering it, it is spider mites. Of all the coleus problems, I find I get spider mites in my plants most often.  Especially when I’m bringing plants from the outside indoors for the winter.

Be very careful selecting plants to bring indoors. Consider spraying your plants with an insecticidal soap as a precaution before bringing them inside. I’ve brought spider mites into my house before. It is not pretty.

Spider mites prey on weak plants. Keeping your coleus healthy is the best way to avoid these and most other pests. However, that is easier said than done. Just a day or two of forgetting to water can leave them weak enough for these pesky mites to attack.

If you notice just a few webs on some of the leaves, start with a good spray with the hose. This will have to be done often to be effective. Insecticidal soap spray can be purchased from any garden center. Use this weekly or as directed to get rid of the mites.

Aphid Infestation

Aphids are a common problem with all plants, including coleus. These are the little transparent bugs that line the stems and underside of the leaves. They suck the life out of plants. Again, aphids attack weak plants, so healthy coleus is far less likely to get an aphid infestation.

I always start by blasting aphid-infested plants with the hose and hand-squishing them off if there are not many. But if they get too out of control, it is time to spray your coleus with an insecticidal soap. Make sure to spray the stems and undersides of the leaves where the aphids like to hang out.