First aid for itches ouches
Opuntia and related cacti, such as Cylindropuntia, have two types of spines. The long, wickedly pointed ones are the most visible, but tiny, hairlike spines called glochids grow in clusters at the base of larger spines. These readily break off when handled and work their way into the skin, causing intense irritation. Given their prickly nature, hand-weeding a cactus is out. Instead, mulch with a five-centimetre-thick layer of pebbles to suppress weeds; any that do appear can be pulled out at the base with fine-nosed pliers. Despite these precautions, if you do have a close encounter of a prickly kind, remove true spines from your skin with tweezers or pliers (it's a painful process!); remove glochids by lightly pressing masking tape over the area and quickly pulling away the tape.
When choosing hardy cacti, find out where the original plant was collected from. Selections from northern areas (e.g., Canada, North Dakota) tend to be considerably hardier than those of the same species from Mexico, Texas or California.
Making new plants
• Multiply prickly pears and chollas by rooting their pads or stem sections before placing in coarse, sandy soil; best done during active growing season
• Divide clumps of ball-type cacti in early spring
• Fresh seeds sprout readily; dried ones may take several years to germinate, as well as require a few three-month periods of alternating cold and warm stratification to break dormancy
Growing cacti is often easier than naming them. Many cover huge territories (brittle prickly pear, for example, ranges from Texas to near the Arctic Circle and from the Pacific Coast to Ontario) and exhibit considerable physical variability as they adapt to local conditions. Also, cacti, notably Opuntia spp., are notoriously promiscuous-place two different species together and it's very likely they'll cross - so natural hybrids abound. Consequently, many species have been classified under different botanical names. DNA studies are making some sense out of the confusion, but be aware that no matter what name your cactus currently bears, it may well change in the future.