One raised bed in our community garden 7.5' x 7.5' is infested with bindweed from last year's gardener. We hesitate to re-assign it to someone new. Any ideas how to get rid of the weed. Black plastic cover and no use for a year? Dig out all the dirt some inches down and replace with new?
Denver County Colorado bindweed
Replacing the soil in the raised bed probably would not be a permanent solution because the bindweed roots are so deep they most likely extend beyond the raised bed so the bindweed eventually would reappear in the new soil.
Herbicides are your surest best, but if your community garden doesn't permit their use or you choose not to go that route, then plastic and persistence are your next best options.
Here's more information: http://planttalk.colostate.edu/topics/weeds-cultural-problems/2104-controlling-bindweed/