Check out this article: How to Refresh an Overgrown Succulent Plant. You really need rocks. Find out why in my review. In garden beds and those areas that guests see first or are likely to linger, be vigilant about weeding. Spines, which are needle-like structures found on the surface of cactus, can be described as modified leaves. The plump leaves of the plant tend to be a grayish-blue with a hint of pink. This will give you a chance to detect any hidden pests and treat an individual plant rather than your entire garden. This is what I discuss in Designing with Succulents (2nd edition).