Awesome find, PP. If there are any trees shading the patch, cut them down (if they're not too valuable to you) because the raspberries will expand their territory and be fatter in full sunshine and if you thin out any competing bushes and weeds. We have a patch here, but, unfortunately it's on the north side of our garage (it was here when we bought the place) and we'd have to tear down the garage to give ours more sun, so that ain't happening.