We moved to a house in central Virginia which there was an already established cactus plant. I was wondering how to weed it without using round up? Is there some other chemical that will kill the grasses that has grown up in it? Any ideas? Or should I use round up and try to get a day where there is no wind and try to spray just the grass and other weeds? Thanks for any help that I can get

What you can do is use roundup on a paint brush. Let the grass grow long and then paint roundup on. Roundup is systemic, so you only need to get it on the upper part of the grass. Adding a little rubbing alcohol to it allows it to etch into the plant better. Or use a piece of cardboard as a shield and then spray it.