It turned out, it is hard to convince farmers to ditch their trusty excel sheets and notepads and start typing all those info into computer program. I managed to find few customers, but they haven't stick for longer than one year.
I spent about one year of fulltime work (spread over two years). I always tried to expand the product: I started with vineyard management software, then add the production part and then started coding all the CRM, POS and warehouse management. I hoped to attract more users with more complex solution, but I was wrong.
After three years I am still using it daily (I do own winery), but I am only active user right now and I did give up trying to sell it. I do some occasional development, from time to time when I need something in my farm, but thats it.