WHY AREN'T MY IRISES BLOOMING?

HORTICULTURE TOPIC: Why Aren't My Irises Blooming?

Irises are known for their beautiful, showy blooms, but if yours aren’t flowering, you’re not alone. At our recent meeting, Horticulture Chair Nancy Percivall discussed common reasons why irises may fail to bloom and how to fix them. The iris, named after the Greek goddess of the rainbow, is celebrated for its striking form and dazzling range of colors. With over 300 recognized species worldwide, irises vary widely in size—from dwarf varieties just 6 inches tall to towering types that can reach up to 5 feet, such as Iris pseudacorus and some Japanese or Louisiana irises. Overcrowding is a common issue, as irises multiply quickly and compete for nutrients and space; Nancy emphasized dividing clumps every three to five years to ensure healthy growth and flowering. Planting depth also matters—if rhizomes are buried too deep, they may not receive enough sunlight. Nancy advised keeping the top of the rhizome exposed or just barely covered for best results. Irises also require at least six hours of direct sun daily; too much shade can result in lush foliage but no flowers, so relocating to a sunnier spot may help. Too much nitrogen can inhibit blooming by promoting leafy growth instead; Nancy recommended using a low-nitrogen fertilizer like 5-10-10 in early spring and after blooming. Improper pruning is another factor—cutting back leaves too soon weakens the plant, so it’s best to let foliage die back naturally to allow energy storage. Finally, newly planted or recently divided irises may take a season to establish before flowering. Patience and proper care are key. As a fun note, Vincent van Gogh, captivated by their bold color and unique shape, famously painted irises during his stay in a psychiatric hospital, seeing in them a symbol of hope and freedom. By following Nancy’s expert tips, you can help your irises thrive and enjoy their spectacular blooms year after year.

Nancy Percivall, CVGC Horticulture Chair