See How to Refresh an Overgrown Succulent Gardens. You will need rocks. Check out my review to find out why. Take care to weed in the garden beds, and areas that guests often see first or where they are likely to linger. The needle-like structures present on the surface of cactus are known as spines and represent modified leaves. The plant's plump, grayish-blue leaves have 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. I cover this topic in Designing with Succulents (2nd Edition).