Will the recent mild winter temperatures around the country impact the winter dormancy cycle of the bearded Iris? Hard to say at this point. Iris are tough. However, any heaving of the soil from the hard freezes which might still come could dislodge the rhizomes, which could be disastrous for their survival. We recommend keeping a close watch on the Iris beds should the weather bring hard freezes. A winter protection can help minimize any potential damage typically caused by hard freeze cycles. Straw, evergreen branches or leaves, or even mounding the soil up around the rhizomes are recommended forms of winter protection. The key with winter protection is to remove it when the threat of hard freezes has passed in the spring. If a spring-time freeze is forecast after new shoots have begun to show, be sure to shield these shoots with recommended protection.
So, what do Iris do all winter? They sleep – or rather, they prepare for the springtime show. Bearded Iris grow best in temperate climates because they require a dormant period which is brought on by winter’s low temperatures (consistently below 40° Fahrenheit (below 5° Celsius) for an extended duration). This dormant period allows the rhizome to convert the energy, which it collected all spring and summer through the plant’s foliage, into the production of new foliage and bloom stalks. Should the current warm trend continue in areas that typically see much colder temperatures this time of year, gardeners might see mixed results in the springtime bloom of the Bearded Iris. Unusual weather patterns, such as sudden freezes following periods of mild temperatures can result in bent stems or wavy leaves (known as “pineappling”), for example. Despite the disfigured appearance of the stem and foliage, the plant is healthy. As long as the rhizome remains firm, the plant will continue to grow. Remember, lack of bloom does not necessarily mean that the Iris plant has died.
We hope that you have found this tidbit of information useful. We welcome your questions and comments in the Comments section below.
Here we share a collage of images from our archives of the Display Gardens in winter through the years …
May you find peace and fulfillment in gardening!
Happy New Year!
The Schreiner Family