If your back is in good shape, try hand pulling. Set a timer for
10min each week, leave the smaller weeds for the next week. You'll be
weed free in no time. Here's some fancy gadgets to look for:

http://www.leevalley.com/home/search...=1&pageGroup=1

Also consider doing something like this:

http://www.cityline.ca/homeandgarden...D=43&topicID=4
http://www.cityline.ca/homeandgarden...D=45&topicID=4