White Owl's Eyes not pool-friendly 2–3 feet in containers or

2–3 feet in containers or tight groupings

This staked form grows as a small upright tree rather than a sprawling shrub

Foliage Evergreen — blue-green to gray-green knobby stems year-round Form Monstrose — irregular bumps and ridges

Absolutely — this is one of the best crested cacti for container growing

Plant it away from walkways and play areas

White Owl's Eyes not pool-friendly 2–3 feet in containers orThe Prettiest White Clumping Cactus for Phoenix Container Gardens Mammillaria parkinsonii (White Owl's Eyes Cactus) is a stunning silvery white clustering cactus prized by collectors and landscape designers alike. Its dense white radial spines create an almost woolly appearance, and in spring it erupts with a crown of delicate pink flowers. This compact, easy care species thrives in the Phoenix Valley's heat and is perfect for containers, rock garden