Hi I have been trying for years to grow healthy Basil plants, I have tried seeds, plugs and those plants you get from the supermarket. The basil always seems to get so big, then the stems near the soil go black and it gets covered in tiny flies. I keep the plants on my kitchen window sill, as they are mediteranean plants, but this seems to happen every time!!! I don't want to spray them with insecticide, and whaen I used a soap solution the plant died spectacularly (although I suspect I may not have made the soap solution correctly ) any helpful hints would be much appreciated!!