Common Reason Why Irises Fail to Bloom

03.05.2024 - 14:12 / gardenerspath.com / Nan Schiller

11 Common Reasons Why Irises Fail to Bloom

Irises, Iris spp., are flowering perennial rhizomes for USDA Hardiness Zones 3 to 9. They bloom in full sun from late spring to midsummer with organically rich, well-draining soil.

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Our guide to growing irises has all you need to introduce these showy seasonal blossoms to your outdoor living space.

This article focuses on understanding and avoiding 11 common reasons irises may fail to bloom. Here’s what we’ll cover:

Let’s jump in and solve this problem!

A plant that falls victim to disease is unlikely to perform well because it devotes energy to fighting pathogens instead of producing lush foliage and flowers.

Four ailments that may pose a threat are:

1. Fungal Crown Rot
2. Leaf Spot
3. Rust
4. Soft Rot

An aggressive soil-borne fungus, Sclerotium rolfsii, causes fungal crown rot, aka southern blight. The leaves turn yellow, then brown, becoming wilted and mushy at the base.

In moist, humid conditions, a cotton-like coating and yellow spores may be visible on the foliage and nearby soil.

Remove affected plant material and sanitize garden equipment. Consider treating new rhizomes with a 10 percent bleach solution (nine parts water to one part bleach) before planting.

Submerge each rhizome, promptly remove, allow it to dry, and plant.

The Cladosporium iridisfungus causes leaf spot. It causes wet lesions on the foliage that merge to create large dry patches. Remove all affected material and apply a foliar fungicide like neem oil.

The Puccinia iridis fungus causes rust and looks like reddish blisters that merge, resulting in a thinning