Purchase the Seeds. Florence fennel is grown for its bulblike stalk, while regular fennel is grown solely for its herby foliage. Both the bulb and the edible foliage of Florence fennel have a sweet, licorice-like flavor.The seed is sometimes sold as sweet fennel or under its Italian name finocchio.arvest Sweet Florence Fennel. When the fennel is about 12 tall, begin harvesting some of the feathery foliage to use as an herb. Once the swollen bulb is about 3 to 4 wide, it is ready to harvest. View original photo.