Walnut blooms in May, along with the beginning of the opening of the leaves. At the same time, on the same tree, the staminate (male) and pistillate (female) flowers do not open at the same time, but with a difference of about a week.
The staminate flowers are arranged in catkins, located on the increments of the previous year. For medicinal purposes, they are carefully collected from a tree, dried in the shade or in special dryers (at a temperature of 50 degrees), and then ground on a coffee grinder and poured into paper bags.
The shelf life of dried walnut flowers is 1 year.