It's the year of the iris, and it's time to divide

By Lynette L. Walther | Oct 01, 2020
Photo by: Lynette L. Walther Every color of the rainbow, that’s what you get with bearded iris.

Novelist and garden observer, John Updike, apparently was no fan of bearded iris. In his novel “Rabbit Run,” his main character, Rabbit, waxed poetic about the unfolding of flowers and foliage in the spring, praising the trumpets of azaleas, the ruffled rhododendrons he took care of while working as a gardener. But when it came to the bearded iris blooms, Rabbit observed them as the “ugly purple tatters.”

However in the opinion of many, bearded iris are some of the most spectacular late-spring, early-summer blooming perennials.

Also called German iris, these tuber perennial plants produce large, handsome blooms in every color of the rainbow with many variegations and flower forms. Their distinctive drooping sepals display a fuzzy “beard,” hence the name bearded. If you have not already cleaned up the iris bed and made divisions, now is the time.

There are many species of iris, and most only need a quick trim of foliage in the fall. But bearded iris benefit from a specific end of season routine.

According to the National Garden Bureau (NGB), unlike most perennial irises, which remain green and lush through the summer, the bearded iris go into a partial dormancy six to eight weeks after flowering and their foliage dies back a bit at the tip. Normally that would be the time to divide them, but some folks like to wait until the end of the season.

Most other irises can stay in the same spot for ten years or more without needing division. However bearded irises decline fairly quickly if we neglect to divide them. After three to five years of growth, most will have reached a stage where no there no longer are blooms in the center and even the bloom on their periphery decreases.

The NGB advises that to divide a bearded iris that has started to decline, start by cutting back its foliage by half or even two thirds. This will reduce its subsequent water requirements as well as transplanting shock. Then, dig up the plant, keeping as many roots as possible.

This will often result with a huge clump, sometimes three feet wide. Rinse the root ball well with a garden hose to wash off enough soil to get a better view of the plant.

With a sharp knife, begin to separate the rhizomes, keeping only the plump ones with a fan of leaves at their tip. Spent rhizomes won’t bloom again and you can compost them. Allowing the divisions a day or so to dry out before replanting is advised. This allows the wounds to heal and reduce the risk of rot.

In a hurry? Brush the wounds with a solution of one part bleach and 10 parts water in order to sterilize them, says Larry Hodgson, the “Laidback Gardener.”

Bearded iris prefers a site with good drainage, one that dries out completely between waterings, unlike some iris which require a lot of moisture. Provide a bed with rich soil which is neutral, with a pH of 6.8 to 7.0 and full sun. Working in some slow-release fertilizer now will help insure plenty of blooms next year.

To replant, lay each rhizome on a mound of soil in which there is a planting hole about five inches deep. Spread out the roots and cover them with soil to anchor the plants leaving about half of the rhizomes exposed and situating them about a foot apart. Alter directions in which fans of leaves point to enable the rhizomes to develop in varying directions. Water in well.

Opinions differ on mulching bearded iris. For neatness some gardeners like to mulch with a thin layer of mulch. Pine needles are a good choice and mulches help to prevent grass and weeds from filling in between plants.

Dividing bearded iris can often result with a surplus of plants, or rhizomes. That’s your opportunity to spread the joy of these dependable blooming perennials.

Help friends and neighbors provide a good home for your shared plants by teaching them how to establish their own bed of bearded iris to spread the joy and color of this favored plant in this the Year of the Iris.

Lynette L. Walther is the GardenComm Gold medal winner for writing and a five-time recipient of the GardenComm Silver Medal of Achievement and the National Garden Bureau’s Exemplary Journalism Award. Her gardens are in Camden.

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Comments (1)
Posted by: Lynette Walther | Oct 02, 2020 09:53

Thank you Lynette for featuring NGB in your article.



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