Cover the seed â¦ I wish all plant producers could be as fantastic as they are they really do take wonderful care of you... Can't say enough! This F1 hybrid was produced by Dowdeswell's Delphiniums in New Zealand who hand-crossed delphiniums to produce seed. I haven't had much luck with delphiniums up here so when I heard about this company I ordered a packet of 25 seeds. Products Per Page. document.write(" "); Plant Delphiniums Seeds: Sow seeds in cell packs or flats, press into soil, fully cover. document.write("