You don't need a card to grow, only to buy in the shops. You can 'donate' to a grower to cover his expenses and he can 'give' you marijuana legally. If your single and growing your own, you can have 6 plants, 3 in late stage flower. (you can only have 3 budding plants per adult) If you have 2 adults, you can have 12 plants, 6 in flower. If you are a carded grower (redbadge), you can have an additional 6 plants for each patient that signs up under you.