Black Spots on Succulents
Sunburns and fungus and virus, oh my. Here’s what to do when black spots spoil your succulents.
Last week your jade plant was gorgeous. This week, there are black spots on its leaves. Gah! What’s happening? Succulents are supposed to be easy to grow and hard to kill and yours looks terrible. Here are some possible problems.
If the spots are mushy, the plant has gotten too much water. It’s drowning. See, succulents store extra water in their leaves, roots and stems so they can survive the arid conditions of their native desert. Too much water overfills the plant’s water storage tissue and causes it to bloat and explode. The black spots are a fungus that has developed in the damaged plant tissue.
Solution: You may not be able to save your succulent. Unpot the plant and check its roots to see if they are still healthy. If they are, trim off all damaged leaves and stems and repot the succulent in dry soil. Go lighter on the watering this time. If the roots are mushy, they’re dead and the plant’s a lost cause. Trim some cuttings off any remaining healthy parts of the plant, let the cut ends callous over and root them in new soil. Yep, just start over by making a new plant. Throw out the mother plant along with the soil it was in because both are probably infected by fungus from the plant rot.
If the spots on the leaves are dry, the leaves may be sunburned. Yep, your sun-loving succulent can get too much sun. This happens when the plant is put in strong light before it’s had time to acclimate to it. If you buy a plant that’s been in partial shade at a nursery and put it on your sunny deck, or move an indoor succulent outdoors, you could end up with burned leaves.
Solution: You can save a sunburned succulent. Remove the burned leaves, because they won’t heal, and put the plant in the shade. You need to give your succulent a couple of days to adjust to full sun, so put it in the sun for three or four hours in the morning on the first day, and increase its sun time by one to two hours per day. Bring the plant inside or place it in full shade at night. By the fourth or fifth day, your succulent will be adjusted, and you can let the sun shine in with no worries of sunburned succulent.
If the spots are small and look like a cascade of freckles, insects may be the problem. Mealybugs, spider mites and aphids feed on succulent leaves, leaving little areas of dead tissue that then grow sooty black mold.
Solution: Remove the damaged leaves and throw them away. To kill the bugs, wipe the leaves with cotton balls dipped in rubbing alcohol, or use insecticidal soap. Repeat the treatment daily till the little buggers are gone.
If the spots are on the underside of the leaves, they may be black ring virus. Tospovirus, the same one that causes tomato wilt, can also infect succulents.
Solution: There’s no cure. Cut the affected leaves off the plant and sterilize your clippers with alcohol when you’re done so you don’t spread the disease to other plants.
Most succulents have very shallow roots, making them easy to dig carefully and replant.
Succulents are pretty low maintenance compared with other plants, but they do have certain requirements for light.
No two gardeners use the same potting mix for succulents, but they all start with similar basic ingredients.