my method is to fling them around in march -although i have done seed sowing in autumn too. and no, don't bother pulling dandelions, their leaves are edible when young and buttercups are just gorgeous. have fun. also, if you are keen on wild flowers, can i recommend chilterns seeds - absolutely the widest variety ever - this year, i am sowing a californian meadow with platystemon, layia, escholzias, phacelia, thelesperma, madia, argemone and chrysanthemum segetum - not all californian i know but....last year, i had an african one with loads of osteospermums, ursinia, arctotis, gazania, gaillardia and felicia. have fun!