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
June 27, 2020 at 12:58 pm
What do you do with a dead bloom from the first bloom of a re-blooming irises? Do I remove it do I cut back all the green?
June 29, 2020 at 9:40 am
Hello. Yes, remove the springtime bloom stalk. Trim the bloom stalk off at its base. Leave the other foliage on attached to the rhizome. Apply a low-Nitrogen fertilizer now (follow manufacturer’s instructions). Water once every 7 to 10 days to soak the top 2 inches of soil. Ensure that soil drains well. Second bloom can be temperamental, and is dependent upon a wide range of factors. Let us know if we can be of further assistance.
October 24, 2016 at 9:49 am
i just turned my last home into a rental property, and decided to dig up about 30 or so shriener iris tubers and not leave them behind with my rental. I don’t have any area as of yet prepared for all those tubers i dug up… What and how can I overwinter them? I was thinking of putting them in a bucket of peat moss and sulfur dust. i live in the seattle area.
December 29, 2015 at 9:21 pm
Here on the coast, the rains have been so heavy and continuous, rhizomes have washed up out of the ground and “floated” away. I have 300+ of your iris and have seen at least 45 “a float.”
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April 8, 2016 at 1:24 pm
My goodness! Please accept our apologies at the long delay in responding to you comment. How did the floating Iris fair? I do hope you were able to recover at least some of them! The warm weather at the Oregon coast must we well-received right about now! The warm temps in the valley are pulling bloom stalks straight up out of the soil. Stop by to visit in May if you can!