See How to Refresh an Overgrown Succulent Gardens. You need rocks? Read my review below. Take care to weed in the garden beds, and areas that guests often see first or where they are likely to linger. Spines, which are needle-like structures found on the surface of cactus, can be described as modified leaves. The plump leaves of this plant are usually grayish-blue with hints of pink. This will allow you to spot hidden pests and then treat a specific plant, rather than the entire garden. In my book Designing with Succulents (second ed.