Indoor succulent mold
This is only a cheap succulent from the supermarket back in April but I really like it. For the last 3 months it has been put in a glass terrain (it looks like a mini greenhouse) in a conservatory and today I’ve just noticed this growing on it and tried to wipe it off but ended up breaking some of it off. Have I killed it? As you can see it has grown in height (unfortunately it has grown curved because of the shape of the terrain!)
Certified GKH Gardening Expert
Succulents have very large gel filled leaves to store moisture. Because of this, they require a dry climate, and dry soil. A citrus or succulent mix is best. Moist soils and soils that naturally retain moisture will cause mildew, which is what you are seeing. Paired with being in containment such as a terrarium, this makes the perfect environment for mildew to thrive.
Now, lets address the plant... This will eventually grow in a hanging form, with long trailing stems. Because of these, they are usually hung, or placed in an area which allows them to flow or crawl. They will also take root at any point that touches a suitable growth media. Since they root very easily, they can be clipped off to make new plants in this way. It will not harm the parent in any way.
Now, the cure... You will have to get that out of a terrarium, and into a container with succulent mix soil. Make sure this is in open air, and has plenty of time to dry out between waterings. To cure the existing infection after replacing the soil, you will mix 1/4 peroxide to 3/4 water and spray the plant, and water into the soil. Make sure to allow excess liquid to drain away. After the one treatment, you will not have to treat again unless this happens down the line. It is important not to mist these plants, either. They do not need it, and often it will cause more harm than good.