Growing Bearded Irises These majestic flowers are surprisingly easy to grow, and actually require less attention than almost any other garden flowers. Your iris roots will arrive already growing in a small pot, with this springs growth beginning. When you plant, you’ll find the root is not really a bulb, but what is called a rhizome–an irregularly shaped bulbous root that grows at a right angle from the foliage. Simply plant the iris as it is, with the top of it showing through the soil surface. Bearded irises grow best with the tops of their rhizomes exposed. Once planted, new foliage and the flower spikes will sprout strongly from the rhizome. Whats more, this summer, you’ll notice the rhizome multiplying for even more flowers as years go by.