I live in northwestern PA and I have this cactus that I grow year round, outside in summer, inside in winter. It does very well. I also always put in impatiens. Had one of my cacti sitting near my impatiens 3 yrs ago, brought it inside in the fall. I thought weeds were growing in the cacti, but I let them go to be sure. Well, sure enough there were impatiens growing in it. I have impatiens year round and I do nothing special for them than I do for my other plants. Is this uncommon for impatiens and should I be doing anything special for them? I have to keep cutting them down, have started other plants, and they are getting ahead of me.