My strawberries do not grow larger than a purple grape!

strawberryplants.org/2015/08/what-causes-small-strawberries

Check the type of strawberry you have, too. Not all types grow to be large.

Plant the strawberries in a hanging pot. Water often.

mulch....mulch...mulch...strawberries needs loads of moisture...keep it in the soil...straw is the cheapest mulch....as for slugs....cornmeal kills them...put in small jar laying on it's side in garden...slugs crawl in...feed...and it kills them. They love it and so do we.

beer also kills slugs, a tin pie plate filled with beer wonders also diatomaceous earth kills them

Clip the runners so the main plant can bare more fruit.

You need the type of plants that produce large berries (I grow several different types of berries so I'll have them all summer and different sizes and sweetness). Second, appropriate fertilizer (see http://garden.lovetoknow.com/wiki/Fertilizer_for_Strawberries). Third, how much sunlight and water are they getting? If the runners have some roots showing I cut the runner off on both ends. And fourth I planted my strawberries in window boxes which I was able to bring inside to "winter" on my enclosed front porch (I kept them inside until the weather was always above 75 degrees). I have tried the beer in deterring slugs (didn't work) and the cornmeal (also got rid of ants besides the slugs). If you can find some old bundt pans or angel food pans and can get your strawberry plants through the center holes you can put about 1/2" of water in the "tube" portion which keeps all sorts of insects away from the plants (if the plants hang down into the water a little it's ok)--just keep an eye on the water level.