I had some in a dry crawlspace in a gallon size zip-loc bag and never got them planted last summer. They had long, white sprouts about 12" long. I assumed they were dried out but when I was cleaning in June the sprouts were still tender. I plopped them in the ground and away they went, so they will store for at least 21 months because I dig in October. Cool and dark with good and careful moisture control is the key. Pack in sawdust, peatmoss, paper bags, or anything that will allow a little airflow but helps retain moisture.