All you need to pick hops is the farming skill. No level is necessary. I'm pretty sure all you need to pick grapes is the farming skill. Winemaking skill is only needed to replant the seeds. Full hands make no difference, a scythe is never needed, any level is sufficient although the lower levels degrade the seeds, so anything harvestable should have been good to go.
So this is rather a puzzle...
Dumb question: Are you sure you have farming, which you get after foraging> plant lore? It can be confusing where you can raise your farming skill level without actually having the farming skill.
Obviously your plant cannot have been ferns, so I am curious what it could have been. Was there any sign that the ground had been ploughed underneath it? If the plant was immature that means that someone must have planted it. What colour was it? pink? Did it have tiny orange semi-circles under each stalk? Were there white dots like aphids all over the plant? Was it as tall as a fern or shorter? Did it look vaguely like marijuana?