This plant has many names including but not limited to Florida Cranberry, Indian Sorrel, Jamaican Sorrel, Rosella, Queensland Jam Plant, Hibiscus sabdariffa.
It is a HOT weather plant that grows up to 6' tall and as wide as it is tall. Plant it outside after the freezes and it will slowly take over a 6' sq patch in your garden. I recommend planting it against something because it will fall over from weight and a supporting fence can be most helpful. Dark green leaves overwhelm the delicate white blossoms which are gradually replaced with ruby red seed capsules. It is the ruby-red calyce surrounding the seed-pod which is the treasure that tea and jam makers lust after.
Watch the calyce grow large and once it begins to open to expose the seed pod within, you can cut the red calyce and pod away from the plant, peel away the calyces to dry for tea or cook into jam.
My first years growing roselle, I would wait to harvest all the calyces at once but found this method impractical because the pods ripen at different times AND molds can set in and damage the pods if there is too much rain and not enough air circulation. Now I harvest the pods as they ripen and peel off the calyces to air dry for tea. The aromatics that jump out of my roselle tea jar are amazing, and the tea itself is scrumptious.
Pick up some seeds at the Seed library and start your plants. Grow them in a protected space away from the freezes, making sure they get 6-8 hours of sunlight. After the danger of frost is past, place them where they can grow BIG without constraint.