The Magic of Irises

The Magic of Irises The backbone of a perennial border I know that everybody’s focus is on vegetable gardening right now, but that doesn’t mean we can’t enjoy the return of our favorite garden flowers, like roses, peonies or irises. Most gardeners are familiar with irises as part of the backbone of a summer perennial border, especially the classic tall bearded iris, bursting into bloom in May and June. However, the world of irises is surprisingly huge, encompassing 280 different species from all around the world. Available in every color of the rainbow and very easy to grow, irises have a place in any sunny garden, and even though bloom is usually quite short-lived for each individual plant, as a group, their bloom can extend nearly all year round. All Iris have strappy leaves, some wide and stiff but others very grass-like. The flowers are sixpetaled, with three upright “standards” and three downward “falls.” The main categories are bulbous, beardless, and bearded, each having distinct care needs. Bulbous Iris include tiny early Iris (such as Iris reticulata, I. danfordiae, and I. histroides), which bloom in February, sometimes coming up through snow, and the popular Dutch Iris (I. xiphium), often sold for Mother’s Day bouquets. While most other Iris have rhizomes, these grow from a bulb similar to a daffodil. These are planted just like other bulbs in the autumn, and will come back every year if conditions are right. A sunny exposure and good drainage are important to keep the bulb from rotting, and a bit of slug control is often necessary as the flowers emerge. Beardless Iris are a huge category, with native species from all over the world. Probably the most commonly grown beardless irises are Siberians (I. siberica), which are free flowering through May and into June, and are very easy to grow. They love regular moisture but will tolerate a wide range of conditions, but they do not want to be in standing water. Japanese Iris (I. ensata) and Louisiana Iris (I. fulva and other species) both love water and will grow in bogs or ponds, but don’t confuse these with yellow flag (I. psueudocorus), a water-loving invasive species on the Washington State Noxious Weed list. Gladwin’s Iris (I. foetidissima), also called roast beef plant, has beautiful brilliant red seeds that last into the fall, but the leaves emit an unpleasant meat-like odor when crushed. Other wonderful species are Algerian Iris (I. unguicularis), which can bloom as early as November and continues to throw flowers all winter, bamboo Iris (I. confusa), which has graceful bamboo-like leaves, and butterfly Iris (I. spuria), which produces huge flower stalks that open in mid-June after all other iris are finished. A Siberian Iris in the Discovery Garden in Mount Vernon brings a startling splash of purple. If you like to plant natives, consider hardy west coast species like Oregon Iris (I. tenax) or Douglas Iris (I. douglasiana), but if you are a collector you might enjoy going down the rabbit hole of Pacific Coast hybrids, which have a reputation for being difficult to grow but include some spectacular blossoms. Modern bearded Iris are believed to come from the species I. germanica, originally native to the Mediterranean. The “beard” is a furry line running down the flower’s throat, and like the flowers, can come in any color. Bearded Iris come in any combination of dwarf, intermediate or tall height, plus standard or miniature bloom, with the shortest usually blooming earliest. Older “historic” Irises often are extremely vigorous and easy to grow, while newer Iris hybrids may be fussier but have ruffles or elaborate features like “horns” or “spoons.” Some bearded Iris, like the white variety ’Immortality’ will rebloom in the fall, making them extremely desirable. The main requirements of bearded Iris are sun and good drainage. They do not like to be heavily shaded, overgrown by other plants, or overly wet, and a lack of flowers usually indicates one of these conditions. They also need to be divided every few years, which is best done in late summer or early autumn when bloom is over but before roots have begun to grow. This is a great reason to have your plants labeled, since by fall they all look the same! Old sections of rhizome can be pruned off and discarded, and the new rhizomes be separated and replanted. When planting bearded Iris, make sure to dig a hole deep enough for the roots, but keep the rhizome itself right at soil level so it is exposed to air and sunlight on top (in hotter climates the rhizome can be shallowly buried). You may want to cut back the leaves when replanting to keep wind from knocking the plant over before its roots take hold. Leaves can also be trimmed in autumn as part of your garden cleanup, but it’s not required for the health of the plant unless you have pests or disease that need removal. Apart from occasional division and weed control, irises are an easy care plant that will keep blooming in your garden for years to come. And it’s impossible to stop at just one. Removing overgrown iris clumps at the Discovery Garden in Mount Vernon.