How to Divide and Transplant Perennials in Southeast Wisconsin

In southeast Wisconsin, there are many perennial plants that can (and should!) be divided and transplanted in the fall. Dividing perennials not only helps rejuvenate old plants and control their size but also provides new plants for other areas of your garden. Fall division allows these plants to establish their root systems during the cooler months, which can lead to stronger, healthier plants in the spring.

Here are some perennials that are typically good candidates for fall division in southeast Wisconsin:

1. Daylilies (Hemerocallis): Daylilies can be divided every 3-4 years if they become too crowded or if flowering decreases.
2. Hostas: These shade-loving plants can become very large and might benefit from division every few years.
3. Peonies (Paeonia): While they don’t require frequent division, older clumps can be rejuvenated by dividing them in the fall.
4. Siberian Iris (Iris sibirica): These can be divided when flowering decreases or they become overcrowded.
5. Bee Balm (Monarda): Divide when centers of the clumps die out or plants become less vigorous.
6. Goldenrod (Solidago): These can be divided to maintain their vigor.
7. Astilbe: When flowering decreases, it’s a good indication they need dividing.
8. Black-eyed Susan (Rudbeckia): Divide if plants become too crowded or if the center of the clump dies.
9. Coneflower (Echinacea): Like Black-eyed Susans, divide when overcrowded or if the center of the clump dies.
10. Yarrow (Achillea): Divide every 3-4 years to rejuvenate plants.
11. Phlox: Dividing can help reduce susceptibility to powdery mildew and other issues.
12. Coreopsis: Divide every 2-3 years for best performance.

Steps to Successfully Divide and Transplant Perennials

• Plan to divide perennials a few weeks before the first hard frost so that the plants have time to establish roots before winter.
• Water the plants a day or so before you plan to divide them; this will make the division process easier, ensure the plants are well-hydrated, and reduce stress on the plants.
• Using a sharp spade, dig around the perimeter of the plant, going deep enough to encompass the majority of its roots. Gently lift the clump from the ground.
• Separate the plant into smaller sections either by gently pulling apart with your hands or using a knife for tougher roots. Ensure each division has 2-3 growth buds and a good amount of roots.
• Dig holes for the new divisions, ensuring they’re at the same depth as they were previously planted. Space them appropriately for their mature size. Fill in with soil and water well.
• After dividing, replant the perennials immediately. Plant them at the same depth they were previously growing
• Mulch around the newly planted divisions to retain moisture and provide insulation for the upcoming winter. Water regularly until the ground freezes.

Remember, while many perennials can be divided in the fall, some prefer spring division. Always research specific plants before dividing to ensure you’re choosing the optimal time for the process.

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