Iris is a flowering plant genus of 310 accepted species with showy flowers. As well as being the scientific name, iris is also widely used as a common name for all Iris species, as well as some belonging to other closely related genera. A common name for some species is flags, while the plants of the subgenus Scorpiris are widely known as junos, particularly in horticulture. It is a popular garden flower.
Bearded Iris, scientifically known as Iris x germanica, is native to Southern Europe and the Mediterranean region and is widely cultivated for its ornamental value. This iris usually blooms in late spring to early summer, with the blooming period lasting up to three weeks. Some reblooming cultivars provide a second flush of flowers in summer or fall.
Bearded Iris blooms in spring and comes in a variety of colors including red, orange, yellow, blue, purple, brown, white, pink, and many bicolors. The flowers are composed of six petals: three upright petals (standards) and three drooping petals (falls). The falls often have a fuzzy or “bearded” patch, which is a contrasting color to the rest of the flower, giving the plant its common name.
Plants sprout from underground rhizomes, forming lush clumps of green, sword-like foliage and, depending on the particular cultivar, plants can grow over 3 feet tall. However, there are dwarf cultivars that typically grow to a height of around 8 inches. This plant is considered deciduous, as the foliage eventually yellows and dies while the rhizomes collect all the nutrients to create new plants and bloom again.
There are two basic types of bearded iris based on their blooming habits – those that bloom only once in springtime or early summer and the reblooming types, which bloom again in fall.
Bearded Iris prefers full sun to partial shade and well-drained soil. It is a hardy plant, tolerant of a wide range of conditions, and is generally easy to grow. However, it is susceptible to pests such as the iris borer and diseases like soft rot if not properly cared for.
The plant grows from rhizomes, which should be planted shallowly, with the top of the rhizome exposed. The rhizomes should be divided every few years to prevent overcrowding and to ensure continued blooming.
When planting iris bulbs in pots and deciding which cultivar to grow, determine whether one round of blooms is enough to fulfill your desires or more is better. Most reputable plant sellers are able to identify whether a particular bearded iris is a reblooming variety or flowers only once each year.
Bearded irises make excellent border plants, cut flowers, and companions for other perennials like roses, peonies, salvia, daylilies, and Russian sage. Dwarf varieties work well in rock gardens.
In terms of USDA hardiness zones, Bearded Iris is quite hardy and can grow in zones 3 through 9. This means it can tolerate a wide range of climates, from cold regions with temperatures as low as -40°F (-40°C) to warm regions with temperatures as high as 20°F (-6.7°C).
Classification of Bearded Iris (Iris x germanica)
The bearded irises are classified by their ultimate size at maturity. The American Iris Society breaks down the iris as follows:
- Miniature Dwarf Bearded: These are the smallest of the bearded irises, growing around 8 inches tall and producing the earliest blooms.
- Standard Dwarf Bearded: Plants range from 8 inches to 16 inches tall and begin blooming as the flowers on the miniature dwarf bearded plants are fading.
- Intermediate Bearded: This is another early bloomer, blooming around the same time as the miniatures and standard dwarfs, with plants averaging around 16 inches to 27.5 inches tall.
- Border Bearded: The ruffled flowers are smaller versions of the tall bearded types and bloom in late spring to early summer. Plants grow anywhere from 16 inches to 27.5 inches tall.
- Miniature Tall Bearded: Called table irises due to their suitability as arrangements, plants produce dainty and delicate blooms and grow 16 inches to 27.5 inches tall. Blooming occurs in late spring or summer.
- Tall Bearded: Plants bloom in late spring or summer, producing ruffled flowers on plants that grow 27.5 inches tall and even taller.
Cultivation
Growing Irises in Pots
- Choosing the Right Pot: Select a pot that is at least 12 inches in diameter and has good drainage holes at the bottom. The pot should be deep enough to accommodate the iris rhizomes, which should be planted just below the soil surface.
- Soil Mix: Use a well-draining soil mix that is rich in organic matter. A good mix can be made by combining equal parts of compost, peat moss, and perlite. This will provide the necessary nutrients and aeration for the iris roots.
- Planting: Plant the iris rhizomes with the roots spread out and the top of the rhizome just below the soil surface. Space the rhizomes about 8-12 inches apart. Water the soil well after planting.
- Sunlight and Location: Place the pots in a sunny location that gets at least 6 hours of direct sunlight per day. Bearded irises prefer full sun, but they can tolerate partial shade.
- Watering: Water the irises regularly, keeping the soil moist but not soggy. Allow the top inch of soil to dry out between waterings. Overwatering can lead to root rot.
- Fertilizing: Feed the irises with a balanced fertilizer once a month during the growing season. This will provide them with the nutrients they need to produce healthy growth and blooms.
- Winter Care: If you live in a cold climate, you may need to move the pots to a sheltered location during the winter to protect the rhizomes from freezing temperatures. Alternatively, you can bury the pots in the ground to provide insulation.
- Pruning: Cut back the foliage to about 6 inches above the soil surface after the flowers have faded. This will encourage new growth and prevent the plant from going to seed.
- Dividing: Divide the iris clumps every 3-4 years to prevent overcrowding and promote healthy growth. Lift the rhizomes from the pot, separate them into smaller sections with healthy roots and fans, and replant following the same planting instructions.
- Pest and Disease Control: Keep an eye out for common iris pests and diseases, such as iris borers, thrips, and fungal diseases. Treat any issues promptly to prevent them from spreading.
Propagation of Bearded Iris
Division
This is the most common and easiest method of propagating Bearded Iris. It involves dividing the rhizomes into smaller sections, each with a fan of leaves and a portion of roots. The best time to divide Bearded Iris is in late summer or early fall, after the plant has finished blooming.
Here are the steps to follow:
- Dig up the clump: Use a garden fork or spade to gently lift the entire clump of Bearded Iris. Be careful not to damage the rhizomes.
- Trim the leaves: Cut the leaves back to about 4-6 inches to reduce water loss. This also makes it easier to handle the rhizomes.
- Inspect the rhizomes: Look for firm, healthy sections of the rhizome, each with at least one fan of leaves and a portion of roots. Discard any sections that are soft, mushy, or show signs of rot.
- Divide the rhizomes: Use a sharp knife or garden shears to cut the rhizomes into smaller sections. Each section should have a fan of leaves and a portion of roots.
- Let the rhizomes callus over: Place the divided rhizomes in a cool, dry place for a few days to allow the cut ends to callus over. This helps prevent rot and disease.
- Plant the divided rhizomes: Plant the divided rhizomes in well-draining soil, with the growth point just above the soil surface. Water well and keep the soil moist until the plants are established.
Seed Propagation
- Collect the seeds: Collect the seeds from the spent blooms in late summer or early fall. The seeds are usually located in the seed pods at the base of the flower stalk.
- Prepare the seeds: Soak the seeds in water for 24 hours to soften the seed coat. This helps with germination.
- Sow the seeds: Sow the seeds in well-draining soil, about 1/4 inch deep. Keep the soil moist but not soggy.
- Germination: Germination can take several weeks to several months. Be patient and keep the soil moist until the seeds germinate.
- Transplant the seedlings: Once the seedlings have several leaves, transplant them to individual pots or directly into the garden.