The iris is a globally recognized flower, admired for its intricate structure and the vast spectrum of colors reflected in its genus name, which is derived from the Greek word for “rainbow.” Cultivating this perennial offers a rewarding experience, but successful planting requires understanding the various forms in which irises are sold. A gardener must distinguish between buying live plant material for propagation and purchasing pre-cut blooms for immediate display. The purchasing decision also involves selecting the right physical form of the plant and timing the acquisition to align with seasonal planting requirements.
Sources for Live Irises (Rhizomes and Potted Plants)
Gardeners typically acquire irises intended for planting through two main channels: local suppliers and specialized mail-order companies. Local retail options, such as independent nurseries, allow the buyer to physically inspect the plant material before purchase. This inspection is beneficial for ensuring the plant stock is healthy, firm, and free from pests or signs of rot. Local experts at these nurseries can also provide region-specific advice on planting times and soil amendments.
However, local garden centers and big-box stores often stock a limited range of common varieties, generally focusing on the most popular Bearded Iris hybrids. For access to rare colors, unusual patterns, or specialized types like historic cultivars, mail-order suppliers become the preferred source. These online retailers or specialty farms offer a selection that spans thousands of cultivars, far exceeding the inventory of any single local store.
While online purchasing offers unparalleled variety, it prevents the customer from visually assessing the health of the rhizome or potted plant prior to shipping. The material from online vendors is generally shipped during the peak planting season. Specialized iris farms typically focus on the highest quality stock, often shipping freshly dug rhizomes immediately after the plant’s summer rest period. This direct-from-grower model ensures a wide selection of healthy stock, provided the buyer is prepared to plant quickly upon arrival.
Choosing the Right Form (Rhizome, Bulb, or Potted)
Irises are primarily sold in three distinct physical forms, each representing a different approach to cultivation. The most common form is the rhizome, a thickened, horizontal underground stem that stores nutrients for the plant. Bearded Irises, the largest and most widely recognized type, are almost exclusively sold as rhizomes. These rhizomes should be firm to the touch and possess healthy, trimmed roots. They are ideally planted with the top surface exposed or only lightly covered with soil to prevent rot.
A second form is the true bulb, a specialized underground structure designed to store food in layers of modified leaves. The Dutch Iris (Iris hollandica), a popular variety, is grown from a bulb and is typically smaller than the bearded type. These bulbous irises generally require a colder dormancy period and are often used primarily for cut flowers.
The third option is the potted plant, an actively growing iris sold in soil, often found at nurseries in the spring. Potted irises provide immediate gratification, as they are usually in bud or bloom when purchased, allowing the buyer to confirm the flower’s color and size instantly. They are often more expensive than dormant rhizomes or bulbs due to the cost of growing them to maturity. Potted plants generally offer a smaller selection of cultivars compared to the vast range available as dormant rhizomes.
Purchasing Iris Cut Flowers
For those seeking the beauty of irises for an immediate indoor arrangement, cut flowers are the appropriate purchase. The Dutch Iris is the variety most frequently sold as a cut flower due to its long, straight stem and lasting vase life. These blooms can be sourced from a variety of retailers specializing in floral products.
Dedicated florists offer irises either as standalone bouquets or integrated into custom arrangements, ensuring high quality and careful handling. Grocery store floral departments also regularly stock Dutch Irises, providing a convenient and generally more affordable option. Farmers markets, during the iris blooming season, can also be a source for locally grown cut irises, which may include unique varieties.
When selecting cut irises, look for stems that feel firm and where the buds show some color but are not yet fully open. Choosing buds that are still closed will maximize the time the flowers spend blooming in the vase.
Timing Your Purchase and Planting
Successful establishment of irises relies heavily on purchasing and planting the material at the correct time of year.
Bearded Iris Rhizomes
The optimal period for planting Bearded Iris rhizomes is late summer through early fall. Planting during August or September allows the rhizome sufficient time, typically six to eight weeks, to develop a robust root system before the ground freezes. This root establishment is necessary for the plant’s survival over winter and its ability to produce blooms the following spring.
Purchasing rhizomes too late in the fall, especially within six weeks of the first hard frost, increases the risk of the plant not establishing roots, leading to poor overwintering and potential rot. Spring is not the ideal time for planting dormant rhizomes, as they may focus energy on developing foliage instead of roots, potentially delaying the first bloom until the second year. Potted irises, however, can be purchased and planted in the spring to enjoy immediate flowers, though they may require more attention to watering during the summer heat.
Bulbous Irises
Bulbous irises, such as the Dutch Iris, follow a different seasonal schedule. These are purchased and planted in the fall, generally after the weather cools but before the soil becomes frozen. This fall planting is necessary to provide the bulbs with the extended cold period they require to stimulate the growth cycle that results in spring bloom. Adhering to these seasonal windows ensures the iris plants thrive and deliver their expected display.