I spent the day picking dandelions myself! Let's see- you can freeze them, no problem. I've read that some people do leave a little green (the calyx area) on the flowers, but I never have. I depetal them all- a real pain, but awesome wine. My recipe is in the database. I've read that the green stems and/or calyxes can impart a bitter taste to the wine, so I've always removed all green. I picked three or four grocery bags of whole flowers and ended up with 600 grams of flower petals (enough for only two gallons) so I froze them until I can collect some more tomorrow.