Onion Sets - F1 Centurion RHS Award of Garden Merit winner. There is no doubt in our minds why the Onion Sets - F1 Centurion is a winner of the RHS Award of Garden Merit. It is simply superb. Producing heavy crops that mature early, this first rate onion is very strong growing. The Onion Sets - F1 Centurion will fare well in the indifferent British summers and produce beautiful onions all the same. The even skin colour and uniform globe shaped bulbs create stunning onions, perfect as a show bench subject. Not to mention they taste absolutely great! They’ll certainly enhance any meal you add them to.