The brown spots on the succulents can be due to various reasons like
sun damage, overwatering, underwatering, or pest infestations, and once noticed, try to find out the reason at the earliest so that these brown spots can be fixed.
How To Fix Brown Spots On Succulents?
- If the brown spots are due to excess sun, keep your plant in shade.
- Avoid watering an overwatered succulent for some days till the soil is dry. An under-watered plant should be given enough watering and let the soil dry before watering it again.
- Brown spots on succulents due to pests like mealy bugs, aphids, slugs or fungus can be treated with alcohol or pest control sprays.
- Some insects, such as scale, which appear as brown spots on succulents can be treated with a cotton swab soaked in rubbing alcohol. Dab the plant and remove the scale insects.
- Brown spots can also be due to fungal rot. Succulents are resilient plants with thick fleshy leaves, stems or roots that are vulnerable to pests and diseases that can be spotted easily.
- Succulents grow best when the soil is allowed to dry between waterings. In wet or waterlogged soils, succulents develop edema forming brown, airy spots on the leaves. The spots can be formed on the undersides of leaves and are hard to notice at times.
What Causes Brown Spots On Succulents?
Some of the main causes of brown spots on succulents are:
- Pests like mealy bugs, aphids or slugs,
- Fungus, rot and water warts
- Sun burns,
- Warts due to excess water,
- Scratches or puncture marks
All these can lead to brown spots on succulents, but it is very hard to figure out which factor is responsible for brown/black spots on succulents.
Pests feeding on succulents can be tiny aphids, slugs, bigger snails, grasshoppers, caterpillars, and even animals like mice, deer, birds, possums, or kangaroos.
The big animals eat big portions whereas small insects and pests make small marks in the leaves and stalks which later darken leaving brown or black spots as the plant heals. The marks on the succulent are permanent.
Aphids and mealybugs ooze a sticky sap that sticks to the plants thus deteriorating the appearance and they hide in the tender growth like new leaves, further aggravating the situation.
So it is very unfortunate that these small pests make ugly marks on the succulents and it seems impossible to protect your succulents from these pests as they are very common and infest very rapidly. Taking an immediate action is the most significant thing, not just leaving them expecting them to disappear ultimately. Lingering on even for a day or two can result in multiples of mealybugs or aphids waiting to invade your plants.
Aphids have a short life cycle and can be easily removed from the succulents.
- You can make this solution and use it like natural aphid spray with these ingredients:
- Water: two cups
- Vegetable oil: one tablespoon
- Liquid dish soap: one tablespoon
- Add all these ingredients into a spray bottle, shake thoroughly and spray the whole plant.
- This spray should directly come in contact with the pests to get rid of them and ensure that you don’t miss any surface, cracks or crevices where aphids hide mostly.
- This works efficiently as the dish soap damages the aphids’ protective coatings, thus dehydrating them.
- In addition, the oil blocks their spiracles (breathing parts), leading to suffocation.
- To make a more powerful spray, you can replace horticultural oil or Neem oil with vegetable oil. A pinch of cayenne pepper can also be added to it.
- Clean the leaves of the plant with a slightly moist cloth to remove excess soapy remnants, after many hours.
- Repeat this procedure every two or three days till there are no traces of aphids.
- Now, rinse your plant thoroughly to remove excess soap and oil as these substances not only damage aphids, but will damage your plant also.
- Neem oil, insecticidal soaps, and horticultural oils can also be used against aphids. Make sure to follow the instructions on the packaging.
- Diatomaceous earth (DE), a non-toxic, organic material is also effective to kill aphids. Do not apply DE when the plants bloom. It is harmful for pollinators also.
- Aphids can be killed easily by using pyrethrum-based sprays. If aphids on your plant are only a few in number and are not many, they can be crushed with a toothpick and washed off. Also, separate the plant from others till no more aphids are there. Large outbreaks should be dealt with pesticides.
- Dry and patchy spots caused by sunburn can be eradicated by removing the individual leaves and keeping your plant indoor where it receives indirect sunlight. If the spots are squishy and the plant is overwatered, get rid of the damaged leaves and replant the succulent in dry soil.
Aphids can be easily spotted by looking at their color, usually, they are green, black, brown, and can even be orange.
- Mealy bugs are gritty as they can grow resistant to pesticides and have a fuzzy cover for protecting them. They can hide easily and can adjust themselves in the narrow space between leaves and stem, in dried leaves, under the tip of the pot, under the table, under any rubble found around their food source.
- They lay their eggs (300-600) hidden but closer to the plants so that after hatching the little nymphs can easily reach the plant. Mealy bugs are very fast in their early days, covering a larger distance, so they can spread over many plants.
- It is very hard to control mealy bugs, so it is better to detect early and isolate the plant. Keep your garden clean. On finding one or two mealy bugs, squash them with a toothpick or thin skewer. The infected plant and other plants nearby need to be properly checked ( check leaves, remove from the pot to ensure there are no mealy bugs on roots etc.).
- Separate the infected plant and monitor for some weeks for any further eruption. If mealy bugs are numerous, then spray with a 70% rubbing alcohol or isopropyl solution. Various pesticides claim to control mealy bugs but they are not effective like 70% alcohol solution, which needs multiple applications and observations as this is also not 100% effective. As most succulents are prone to getting infected with mealybugs and so you need to regularly check and keep your area clean.
- If a plant is infested with mealybugs or aphids, we also have to check for ants as they appear with these pests. Ants easily spread as these pests produce a sugary honeydew which ants collect.
- Ants also guard mealies and aphids (some scale insects too) from predators like parasitic wasps or ladybugs. This relationship between ants and pests destroys your succulents.
- In this way, ants are also pests and should be stopped from reaching plants.
- This can really be tricky as ants can infest any part of the garden very fast. Chemicals will kill the workers and other insects too. The best way to avoid ants is to keep the garden clean and spray these ants with a pyrethrum-based spray.
Slugs And Snails
- Slugs and snails make little holes into the succulent leaves leading into a series of dark coloured marks.
- They hide in crevices, rocks, under pots, or moist dark areas and come out at night making them difficult to catch.
- The green elimination techniques are good for slugs and snails. Bury a shallow dish of beer into the ground and the slugs will drink to death.
Fungus, Rot & Water Warts
- Fungus infection, rot and warts due to overwatering in succulents are very common in humid and warmer areas of the world. Many succulents of dry and arid environments love to stay away from humidity. Even plants that are watered less often and are kept under cover can be infected with fungus in high humidity.
- Fungal infections in succulents result in black or brown round spots that can grow all over the leaf which will wither and fall off. At times, there can be only one or two spots per plant or many more. The spots can also change into a wart or a scab.
- All of these need to be treated with a fungicide which you can buy from garden centres, online and even big grocery stores. Most fungicides will also harm useful insects and so it is advisable to spray in the evening when they are not active.
- During high humidity, fungicide should be applied every other week. For some succulents, limit watering in an already humid environment, but for others it can result in stress, causing shrivelled leaves.
- Water your succulents once a week when it is very hot, allow the potting mix to dry between waterings. Avoid spraying the succulents with water as they cannot absorb water through their leaves.
- It is recommended to water around the root area for sensitive succulents. Use a succulent potting mix or other well-draining mix in pot plants. It is better to avoid using heavy potting mix that retains water.
- Some succulents like Echeveria, some Graptopetalum, Graptoveria, Pachyveria and Pachyphytum are more prone to getting infected with fungus. Plants such as Echeveria Black Knight, Echeveria Romeo, Graptoveria Amethorum & Pachyphytum Fittkaui get infected with fungus on rainy days.
- It is slow to attack and can be avoided if the plants are kept under cover to avoid rain. Some sensitive plants mentioned above will not have this problem if they are planted in the ground, though the reason is not known.
- If your plant rots and the root, stem & leaves become black and mushy, not much can be done. If the rot has not reached the top part of the plant without affecting the leaves, cut it off from the rotting bit and plant it as a cutting.
- Rot can be hard to find. At times, warning black marks can be seen and at times, the plant will collapse at once. Then the plant cannot be saved at any cost.
- Succulents can get sunburn and different succulents have different resistance to sun, but most can get sunburn as the temperature starts rising over 40°C (104°F).
- The forecast temperatures are the shade temperatures and if you note temperature in full sun during the hottest part of the day, you’d record higher than what the forecast tells. And that’s why even tough plants such as succulents get burns.
- Temperatures above 40°C will cause burn marks on the foliage of most potted succulents. Plants in the garden have more tolerance of sun as the roots remain cool in the ground than in pots.
- Succulents react differently to extremely hot sun as some drop leaves, some fall down in a heap of slush and some get dark coloured marks or spots. The marks due to burns will not disappear, but with time, the plant will come out of the damage.
- Remember that small plants or newly propagated plants are more prone to sunburn than mature plants.
- Move the potted plants to shade to prevent burns during the hotspell. Putting a shade cloth or an umbrella over the plants is also a good idea, if pots cannot be moved. This can also be done for succulents in the ground.
- Frost has similar effects on succulents as the sun. Dark spots develop on the foliage due to frost. In extreme situations, the succulents will collapse.
- Succulents can be protected from mild frosts by using a frost cloth over the plants. Except for a few plants like Sempervivum, succulents are not frosted tolerant and in areas with cold winters where snow remains for several days, it is difficult for succulents to survive outside even with a frost cloth over and should be kept inside in winters.
- Succulents can remain outdoors if there is no frost and the temperatures do not dip below 0 Celsius (32°F). Frost cloth can be used through the coldest of winters in such areas.
Puncture Marks & Scratches
Tiny pests feed on succulents by scratching the surface of the leaves and form brown/ black spots on the plants. This can also happen if anything falls on the succulents, when the foliage is harmed during repotting or if it hails.
Is The Plant Salvageable?
If the stem is pulpy or brittle, check the roots for similar conditions. The roots should be flexible but firm. If both the stems and roots are pulpy or brittle, the plant is dead and you will need to grow a new plant.
Some succulents are more susceptible to black/brown puncture marks and scratches than others except the plants with a good, thick and dusty coating on the leaves and stems called Farina, get marks more easily.
The precaution is to handle succulents carefully and to not rub the leaves. If the damage has been done, the only way the spots will go away is to grow out of them.
Black or brown marks can be due to different reasons. Sadly, they won’t disappear, but will be hidden by new foliage.
The damaged leaves will fall off and new leaves grow in their place.
What Potting Mix Or Soil You Use Can Make A Difference
Cactus and succulent mix are best to be used for succulents. Succulents are plants with lesser water needs that prefer thinner soil that dries out faster. Cactus and succulent mixes have a higher ratio of perlite, sand or other inorganic material to provide perfect drainage and air to the roots.
This is everything you should know about how to fix brown spots on succulents. I hope reading this article will help you not only in identifying the brown spots and reasons behind them, but will also help you in fixing them.