Cactuses intrigued me when I was a child. They posed an interesting dilemma; they would not die, but I could never nudge them into doing anything except producing elongated, etiolated growth. Eventually I found out that to bloom many require a cold dormant period. This led to an occasional foray into the realm of hardy cactuses. Our climate is hardly cactus friendly, but there are plenty of hardy species which will survive and bloom in our gardens. If you decide to give them a try, don't even think of asking me to help weed them.
The plant shown above is Mammillaria plumosa, long a favorite among cactus collectors. It grows wild in northeast Mexico, and has no trouble surviving the winter here in a cold frame. The plant shown in the image had a recent drenching, and so the plumose quality of its spines is somewhat lessened. The big surprise for me, of course, are the flowers. I had other plants of this species in the past, but they were grown as house plants and never bloomed. Yet the young plant shown above is blooming freely: evidently life in the cold frame is good for it.