As yet, I have not been able to classify the specific cacti in my garden. Despite this fact, certain general characteristics pertain to all cacti grown in Iowa. First, as warm climate perennials, they cannot tolerate cold temperatures (usually anything below 40-50° F). This means that they must be brought indoors to overwinter prior to the first frost. Second, all cacti do best in full sun. Third, whenever transplanting any cactus, make sure not to damage the roots. If the roots do become damaged, wait several days to replant the cactus, keeping it dry, or it might rot due to bacteria or other organisms. Finally, if you want your Iowa cactus to flower in the summer, provide it with adequate moisture during dry spells, watering the plant every 1-2 weeks. If you are looking for a plant that is low maintenance, exotic, and easy to transplant, catci are just right for your indoor and outdoor garden.
http://www.bestgarden.net/Photo_Album/Pages/Cactus.htmWATCH YOUR FINGERS!