Re: glyphosate "known to have a half life of at least 2-1/2 years, the use of them has been banned in Denmark because large quantities have been found in their ground water and the USEPA has found glyphosate in the ground water in this country". This is a repetition of completely discredited disinformation that continues to circulate on the web. Glyphosate in temperate soils has a half life of around a month, does not bioaccumulate, and breaks down completely into natural constituents eventually by microbial action. It can only persist for longer periods of time in soils that are frozen. As the CPDR summarizes "In general, glyphosate is moderately persistent in soil. Soil studies have determined glyphosate half-lives ranging from 3 to 130 days (U.S. EPA, 1990; USDA, 1984). The soil field dissipation half-life averaged 44-60 days (Kollman and Segawa, 1995; WSSA, 1989). In the soil environment, glyphosate is resistant to chemical degradation, is stable to sunlight, is relatively nonleachable, and has a low tendency to runoff (except as adsorbed to colloidal matter). It is relatively immobile in most soil environments as a result of its strong adsorption to soil particles." Use of glyphosate has not been banned in Denmark, in fact after examining the science their government stated that they believe that no unacceptable risk of pollution of groundwater is associated with their use of glyphosate. Glyphosate is not a herbicide that has presented groundwater contamination issues unlike atrazine and others. There is much misinformation constantly repeated on the web about glyphosate. For those interested, a decent introduction into the properties of glyphosate is Williams, Kroes, Munro (2000). "Safety evaluation and risk assessment of the herbicide Roundup and its active ingredient, glyphosate, for humans". Regulatory Toxicology and Pharmacology 31-N2: 117-165.â http://www.ncbi.nlm.nih.gov/pubmed/10854122

Best way--and hardest work--is to just keep pulling the bermuda grass out. Water well, then start pulling when the soil firms and water has soaked in a bit. There are a number of herbicides that target grasses, however few of them have labels for flower beds. In some cases, the grass herbicides will also have some activity against certain broadleaves, so if you go off-label and just try something, you might get a few of your flowers as well. You might look at Preen in a small area as it is recommended for grasses, but don't know what it may do to the plants you want.

Last spring , I had a huge crop of it everywhere and I tore it out all spring and hauled it off to the compost heap. When it flowered I pulled the seed heads and bagged them and composted the rest. Irritating plant. Bugs,beetles, flies, bees and butterflies seem to like it. They seem to die in the summer heat and dryness here.

You can use it after the chickweed has gone to seed but it will only kill the plants, not the seeds. You'll need to eradicate the subsequent offspring, by what ever method you choose, possibly several times if seeding has been going on for some time. How big is the area? Is it impossible to set aside some time and methodically pull the plants out?