I couldn't tell whether anybody replied to Alberto's query about using vinegar on weeds. Yes, it works on most but not all weeds. Spray cooking vinegar (5% acidity as sold in the USA) on young weed seedlings. It seems less effective on older seedlings or plants, especially dandelions. By the way, judging by the number of people writing me privately for unobtainable plant material, this is by far the most gullible plant group to which I subscribe. Leo Martin