Hi, Looking to grow some Parsnips which have never done before. Have tried many times with carrots, but always poor results , they never seem to get down into the soil, which is not heavy clay , but does have some in there , though it has had plenty of compost etc over the years. Seems a raised bed or container of sorts is needed, so any suggestions of how deep a container it should be and whats the best medium to use, I assume lots of sand ? Any particular variety suited to northern England ? Only looking for cooking not exhibition.