Boost Your Iris Flower Power: Learn How To Divide and Conquer

Irises are beautiful, hardy plants that bloom in various colors and are easy to care for. According to Greek mythology, the iris is named after the goddess of the rainbow, and the genus consists of around 300 species. Bearded iris are the most commonly planted and have rhizomes, a horizontal root-like structure that provides food storage. Digging up and dividing the rhizomes every 3-5 years is essential to ensure your irises continue thriving and producing beautiful blooms. 

Here are the top 5 steps for successfully dividing your bearded iris rhizomes:

Step 1: Choose the right time

The best time to divide irises is in late summer after they have finished blooming. This mid-summer chore allows the plants to establish new roots before winter. Sufficient rooting typically takes 4-6 weeks and should be timed before the first killing frost.

Step 2: Prepare the soil

Before digging up your irises, prepare the soil. Adding compost or other organic matter is beneficial at this time as it will help improve soil structure and provide nutrients for your plants.

Step 3: Dig up the iris rhizomes

Using a garden fork or spade, dig up the clump of rhizomes. Be sure to dig deep enough trying to minimize damaging the roots. 

Step 4: Divide the clump

Divide the clump into smaller divisions using a sharp knife or garden scissors. Each division should have a single healthy rhizome and a few leaves or "fans." You can discard the older rhizomes with no leaf fans. Avoid composting the older rhizomes, as they can harbor borers.

Step 5: Replant the divisions

Replant the divisions in your well-prepared bed, spacing them about 6-12 inches apart. The top surface of each rhizome should be visible, just above the soil surface. Water the plants thoroughly. Adding a light amount of wood mulch is optional.

By following these simple steps, you can ensure that your irises continue to thrive and provide beautiful blooms year after year. So don't hesitate to get out there and give your irises the attention they deserve! As a bonus, you'll likely have extra divisions for friends and fellow gardeners.

Our video below shows the entire process of digging up a large clump of bearded iris, dividing, and replanting. Enjoy the video!

For additional tips on additional Iris varieties, including Siberian, Unguicularis, and Pacific Coast, visit this article at The Royal Horticulture Society.

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Kevin

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