I've done quite a bit of research over the past several months, and finally settled on an Expert Gardener 4 Amp Electric Trimmer/Edger for keeping the grass in my ditch and at the edges of my lawns Neat. The area is fairly large, so I decided that the 2.2 Amp 8" trimmer wouldn't be large enough, so I went with the 13" 4 Amp unit. I tried it out the other day, and was quite pleased. The ditch and edges along my driveway were pretty overgrown, so it took a while, but it worked quite well. I'd been using a gas trimmer, but had problems with it getting caught in the weeds and choking, but I haven't had that issue at all with this electric unit, so I definitely recommend it. The electric unit is lighter than the gas trimmers, which is why I chose to buy an electric unit and deal with the cord. There are some battery ones available, but I've never had luck with battery tools, so I'm sticking with this, and I'm very happy with it so far. Also, I looked all over the place for the lowest price, and found it at Walmart. There is generic replacement string available if you want to wind it yourself, but I'm going to order replacement cartridges online, since winding is difficult for me.
