Opuntia microdasys, and the varieties of the species, are common houseplants, often encountered in dish gardens or in small pots at big box stores.
Fortunately, O. microdasys is attractive and tends to be of a size that it can be impressive without being troublesome, it's maximum size is three feet tall and wide, but in pot culture, you can expect about half that. It is therefore common as a houseplant, and for some collectors, (who let's face it, can be pretty picky about what plants they're willing to have around) this may be the only prickly pear allowed to rub shoulders with their much rarer specimens.
This native of Mexico is heavily covered with glochids, which are the small hair-like spines that are the calling card of prickly pears, and, like a few other species of opuntia, do not have the longer needle like spines of most cacti.
There are four variations of the species that you may encounter... This, with its yellow glochids, is the standard or main species, and may produce yellow blooms.
Opuntia microdasys v. rufida has glochids that are a cinnamon, reddish brown color, and is sometime called the Teddy Bear cactus.
Opuntia microdasys v. albispina has glochids that are white, and is sometimes called Bunny Ears.
The other variety of the species is a mutation often referred to as Golden Ruffles, where each pad of growth grows ruffled edges, and is properly named O. microdasys v. crestata.
Despite the cute common names, don't feel tempted to give them a cuddle. Glochids are not something that you want to deal with on an up close and personal level. They're not exactly painful, but they can be maddeningly irritating. Duct tape pressed against the skin to yank them out is usually the easiest way to deal with them. To be blunt... I'd rather deal with spines, but there we are.
I've grown all varieties over the years, and the care is more or less identical. They can take all the sun you can give them. They appreciate watering about once a week in the heat of summer, but can take less if they have to... if they start looking limp or shriveled, you may need to water them a bit more... potted plants tend to need more water than specimens in the ground.
Currently, I only grow the yellow standard because it's the only variety that is really winter hardy in my climate. Here, in the Dallas/Fort Worth area on the line between zone 7 and 8, this plant will survive the winter outside provided it's in a pot, rock garden, or in a part of the yard that doesn't collect water. The key to almost any cactus surviving a cold winter outside is drainage.
This species can take cold. But they cannot take cold and wet.
During hard winters, I may lose some of the plant, but there's usually enough to recover so that by late spring it's looking impressive. However, I don't get blooms off of the outside plants, so I'm probably really pushing it's cold tolerance.
The other forms, do not tolerate cold, and must be moved inside for the winter. Placed in the brightest window possible, and watered very little, they will usually overwinter fine.
Besides the cold issue... any good cactus soil, or even any potting soil with lots of perlite and sand mixed in will suit it fine. The plants are pretty heavy feeders, and if they're given fresh soil every spring, they quickly show their gratitude with lots of new growth. Feed them every other watering with about half recommended strength plant food, they'll be happy. While they're heavy feeders, too much food results in growth that is too lush and too soft to stand up for long, especially to cold... I usually stop feeding the plants in September to help them tough up for the coming winter.
Like all prickly pears, propogation is simple from cuttings. Actually, the cuttings root so easily, that Opuntia will often propogate themselves without any help from you. It's not uncommon to find a pad that has broken off, rooting and growing under the parent... but to do it intentionally... break or cut off a pad, let it sit somewhere for a week or two so that the cut edge will dry out, then pot up the pad in soil. Within a month it'll be rooted and growing. If you really want to increase the amount of plants you have, you can actually cut each pad in to four pieces, once from top to bottom and then cut those two pieces in half across. After the cuts have dried, those four pieces will, when planted, each grow roots and pads. I once knew someone who would line a black plastic nursery tray with canvas, fill it with potting soil, and place about fifty of these cuttings of cuttings in there. Each would grow and within 2 months he had plants to pot up and sell in another month.
Personally, as an experiment, I once rooted six pads, two of each of the three color varieties, in a hanging basket. It was interesting looking on the patio, and, with hindsight, it was such a relief to have a hanging basket that didn't need watered twice a day, that I kind of wonder why I didn't do it again...