I had 2 DCO's and a Burgamble stored in moist sphagnum peat, in one quart zip locks, that did not have radicals in the spring. When this happens I put them back in the fridge to plant later. Then fall came and they had radicals, but it was too late to plant. I left them in the fridge until the following spring. At that point they had sprouted trunks (1 to 3 inches) and I opened the bags a touch in February. Planted them in the spring (April) and although they were slow to start, they grew fine. So, 18 months stored - fall 2016 to spring 2018. I have about 20 shagbark hickory I collected in fall of 2017. Last spring 2018, they had no radicals. Last fall, I checked and they had 3 inch radicals. I put them all back in the one gallon zip lock bag with moist peat and they are waiting to be planted this spring.