It is late to plant them but you normally start dry Hedychium / hardy ginger in Feb/Mar indoors. Soak for a few hours then place in a pot with well draining soil in a hot place like a hot water cupboard and keep dampish but not wet as they rot. When the shoots start to come up (can take months) then you place in a windowsill until the first frosts have stopped. You can then plant out where you want to place them and as long as the area is well drained and you cover with a few inches of mulch, they come up by themselves every year - normally June. Normally flower in August/Sept.