First you have to take out the rhizomes you already have and to separate them. Shake the clump to remove any loose soil.
Using your hand or a hand fork, split the clump into manageable pieces. Discard any old rhizomes, then detach the new, young rhizomes from the clump and neatly trim off their ends. Make sure that every piece have at least one healthy leaf and his own roots. Dust the cut areas with fungicide. Trim long roots by one third. Shorten the leaves to about 15 cm long to prevent wind rock.
Find a sunny place in your garden, with hummus-rich soil, preferably acid. Plant the rhizomes about 12 cm apart. The rhizomes should be half buried, with their leaves and buds upright. Firm well and water.