Thanks for the input on the weed issue. I was considering soil amendments before next season, make the soil richer, if even just with lime, to be more inhospitable for them. But I kind of hate to thwart all the other 'good' desert plants I am getting attached to. Ideally i guess I would like to acidize the young growth next year while encouraging more friendly groundcovers. I can see where certain things tend to compete and crowd out the goatheads, where other things happily coexist with it. It is a learning curve. Nice to have a research librarian with lots of answers and ideas handy!