The most inhospitable spots in the garden that no one wants to put any work into seem to be the domain of cacti, whether or not any cacti actually live there. “Oh, I will just put some cactus there!” is cliché in regard to shadeless and dry spots that get too hot with glare from a south-facing wall. Yet, such spots typically continue to be neglected, and the cactus never get planted.
Why are such distinctive and interesting plants considered to be so lowly that they should be banished to the badlands? Why should they be expected to endure what not other plants are expected to endure? After all, there are so many other distinctive xeric plants, like yuccas, agaves and some aloes, that are just as resilient, and according to some, just as lowly.
Cacti really are not as independent as commonly believed. New plants should actually get watered occasionally until they disperse their roots. If they get watered regularly, they need coarse soil that drains very well. Cactus plants that were grown in sheltered spots really can get scaled if planted where they are too harshly exposed during hot weather.
The main problem with cactus is their nasty spines. Simply planting small plants without getting poked is a challenge. Moving big potted specimens or removing overgrown cactus plants without getting seriously perforated can be daunting. So, even though they might do well in the harsh exposure at the curb, they do not belong in such a high traffic area.
Without foliage or conventional stems, cactus are either awkward to prune, or can not be pruned at all. Barrel cactus have only one or very few round stems. If one of these stems gets to wide, it can not be pruned back. Prickly pear cactus is easier to accommodate only because it has enough stems to spare those that grow out of bounds.
What makes cacti so excellent is their distinctive form. Some have strictly upright stems that resemble those of the organ pipe cactus. Some grow as clumps of short and fat stems. Others grow upward and outward with rounded and flat stems like those of the beaver tail cactus.