I make it every spring, it is best to harvest the root when the sap is in the root, which mean as soon as the ground is thawed enough to dig them up.
I prefer the roots of small saplings, with root from 3/8" to 1/2' diameter which I make into an extract Or Tea. By striping off the bark and simmering it for 15 to 20 min
I make it in 3 gallon batches using 1 gallon extract. 2 gallons water, enough sugar to bring to Preferred SG usually 1.090 for me. 3 pounds raisins, 1/2 tsp Tannin, bring Ta to .55% usually around 2 tsp acid blend. Yeast nutrient, and lalvin K1 V1116 yeast. This is also excellent if sugar is replaced with honey.
It is some good stuff and I usually run out before the next batch finished aging. But that's Okay. The anticipation increases the savor.