The Concertina Bearded Iris adds vertical interest and abundant blooms to any garden. This elegant, low-maintenance perennial is a popular choice for borders, cottage gardens, or as a sunny focal point.
What Makes Concertina Bearded Iris Unique
The ‘Concertina’ bearded iris features a unique floral display. Its ruffled petals blend colors like dusty rose or amaranth rose standards (upright petals) with falls ranging from pastel yellow to peach-pink or periwinkle-purple. A distinctive bushy beard, which can be violet-blue, orange-laced, or indigo, contrasts strikingly with the petals.
This reblooming iris offers two main flowering periods: late spring to early summer, and again in late summer or early fall. Mature plants typically reach 22 to 36 inches tall, suitable for mid-border placement. It is also noted for its pleasant fragrance and natural resistance to deer and rabbits.
Planting and Site Selection
Concertina Bearded Iris requires careful site selection, prioritizing ample sunlight. They perform best with at least six hours of direct sunlight daily, though partial shade is tolerated in hotter climates. Good soil drainage is essential, as rhizomes are susceptible to rot in waterlogged conditions.
Ideal soil is well-drained, humus-rich, and slightly acidic to neutral. For heavy clay soil, consider raised beds to ensure proper drainage. Position rhizomes with their tops just at or barely exposed above the soil surface to absorb warmth from the sun. Space rhizomes 12 to 24 inches apart for future growth and air circulation. The optimal planting time is late summer to early fall (July through October), allowing roots to establish before winter.
Essential Care for Thriving Blooms
Ongoing maintenance is important for encouraging vigorous growth and abundant blooms from your Concertina Bearded Iris. While relatively drought-tolerant once established, they benefit from moderate watering, especially during dry spells and their initial establishment period. Allowing the soil to dry out between waterings helps prevent rhizome rot.
Fertilization supports their reblooming habit and overall plant health. Apply a low-nitrogen fertilizer, such as a 5-10-10 formulation, in early spring as new growth emerges and again one month after the spring bloom cycle concludes. Apply fertilizer around the rhizome, not directly on it, to avoid burning the plant. After blooms fade, deadhead spent flower stalks by cutting them back to an inch or two above the rhizome; this redirects the plant’s energy from seed production toward developing new blooms. In late fall, cut back foliage to 6 to 8 inches above the ground to maintain tidiness and prevent overwintering pests. Avoid mulching directly over rhizomes, as this can trap moisture and lead to rot.
Addressing Common Challenges
Concertina Bearded Irises are generally robust, but gardeners may encounter a few common issues. Iris borers represent a significant pest concern, with larvae chewing holes in leaves and tunneling into the rhizomes, leading to internal damage and potential rot. Signs of borer activity include notched leaves or slimy, water-streaked areas on the foliage. Bacterial soft rot is another problem, causing rhizomes to become mushy and emit an unpleasant odor; poor drainage and excessive nitrogen can contribute to this condition.
Leaf spot, characterized by rusty patches on the leaves, can also occur, particularly in wet conditions. Slugs and snails may damage newly planted irises and seedlings. To manage these issues, maintain garden hygiene by removing old foliage and debris, which can harbor borer eggs. Promptly remove any affected plant parts and ensure proper air circulation and drainage to deter fungal diseases and rot.
Propagating and Dividing
Propagating and dividing Concertina Bearded Irises rejuvenates overgrown clumps and encourages vigorous flowering. Irises typically benefit from division every three to five years; reblooming varieties like ‘Concertina’ may require it every two to three years due to faster growth. This prevents overcrowding, which can diminish bloom production.
The best time to divide is four to six weeks after spring flowering concludes, or mid-summer to early autumn (July through September). To divide, carefully dig up the entire clump and gently separate healthy, firm rhizomes, ensuring each section has at least one fan of leaves and roots. Discard any old, withered, or soft rhizome sections. Trim the foliage of separated rhizomes back to 6 inches and shorten roots slightly before replanting at the appropriate depth.