Using a 1" mulch of gravel helps a lot ... the weeds come right off. RJ

I use an environmentally friendly pre-emergent herbicide, corn gluten. It is marketed under several brand names, including WOW (without weeds) and Amaize. I can get it from the feed store, too, but I have to tell them I am using it for livestock feed. Another source is permitted to sell it only to be used as fertilizer (8-0-0). The advantage of the brand name stuff is that it is granulated, and therefore easier to apply if there is any breeze; on the other hand you pay a lot more.

The research has been done on this years ago already, at a Midwestern university. Use Google to search. It is totally safe and leaves no toxic residue. You can even eat it!

Pre emergent herbicide otherwise known as seed germination inhibitor regardles of whether it is organic or chemical will not harm your plants. It simply prevents seeds from sprouting for a month or more depending on the weather conditions, amount of rain etc.

You can use the CGM suggested, but you need to apply it fairly heavily for best results. If you go the chemical route you can use the same stuff that would be put on a lawn to control crabgrass although it can be difficult to find in stores in a pure form, usually it is mixed with a high nitrogen fertilizer which you will want to avoid.

I, also, am having problems with weeds. I have a sloped rock garden about 50 feet long by 6 feet along the side of our pool area with lots of rocks. I use Preen early in the season and throughout, but some of the weeds have underground tubers and it seems like the grasses come from nowhere, not to mention the small trees that try to take root or have already. I brush weed killer on the leaves to try to kill them, but that is so time consuming. I am afraid to spray for fear of hitting the perennials. Any other ideas?

I covered as much of the ground as I could with big old rocks- and I just weed by hand between them- the next door neighbor getting rid of the messy old maple tree in his yard has helped immensely.

Safariofthemind, if you mulch with gravel, how do you handle digging when you need to split or transfer plants. I tried gravel in a couple areas and found it was a pain to deal with later. Could a person use bark mulch?