You can also learn how to deal with common succulent pests if this is your first time dealing with an infestation. Scales can be small, gray-colored oval-shaped insects that are commonly found on succulent stems and leaves. In fact, garden pests have been devastating my aeoniums in the past year. They usually appear in spring and summer, but can survive for a good portion of the growing season. Root rot can be caused by soil moisture. So the soil you plant your cacti in must allow for ample drainage. Cacti look great on a table especially when there are a variety of colours and shapes.