Mine don't grow much during the summer because we don't usually get rain very often from some point in May until some point in August or September. Just yesterday I was thinking that I do need to move the largest one because it's grown to the point that it will soon be encroaching on the handicap accessible ramp I have leading up to the playground. The thorns on the prickly pear cacti that we have aren't too bad. The thorns on the rambling roses are much, much, worse. Even some of the lemon trees have more vicious thorns. The plants that look deceptively less threatening than the prickly pears are the century plants. Those have gashed my leg or arm more than once when I've accidentally brushed against them.