The only way to control grasses growing in a planting bed is to dig out the roots and then place a barrier the grass roots outside cannot get through. Any grass will send roots into the nice loose, rich, soil of a planting bed, there are none so well behaved they would not. Maybe, depending on the grass, you could cover that with a good mulch and stop its growth, if the grass is one of the wimpy fescues that tend to die whenever they feel unwanted.

Oh, perhaps I should have pointed out that we don't have any lawn nearby. We've laid landscape fabric and mulch everywhere we won't have flowers and/or groundcover.

I guess I do have to dig further down, though, and really get at the root. Maybe a thicker layer of mulch will help, also. We went light in order to allow the groundcover to spread, but further research has shown that those groundcovers will need some manual propogation to really fill in quickly.

Thanks.

(Any more ideas certainly welcome.)

Color me surprised! I never expected something like that to actually exist, so I didn't even bother googling for "narrow-leaf herbicide". After your post, I did and I found some. I'll tuck it away for last resort. Thanks!

Is narrow leafed weedkiller still available ? I was told it wasn't I have long strands of grass growing in my flower beds impossible to get rid of driving me crazy what is the brand name and is it obtainable in the UK ?????
ETERNALLY GRATEFUL FOR ANY HELP !!!!

Gordon--what you are looking for is sold in the US as Grass-B-Gone, made by Ortho I believe. For agricultural uses, it is sold as Fusilade, the active ingredient is Fluazifop. I would suspect it is available in the UK.

Other selective grass killers include the ag herbicides Poast, Select, and Assure II.

You can look these up to get the active ingredients, then look for products with the active ingredient in the UK.

I think the ingredient in Grass-B-Gone is probably the safest for your non-grass plants. I've used some of the others on flower beds and found that some are very hard on phlox, iris, corn lillies, and a few others and have started using the active ingredient in Grass-B-Gone since it doesn't seem to affect anything in my flower beds that aren't in the grass family.

It's a good idea to know which are the dicot and which the monocots in your garden. SOMETIMES, these selective herbicides work on one OR the other because of the physiology of the plant. Thus, some other monocots might be injured right along with the grass you want to get rid of. Others seem to be very safe on everything but the grasses.