Dividing Perennials
Daylily - Image via pxHere - CC0 Public Domain
Spring is the perfect time to give your perennial garden a refresh, and one of the best ways to do that is by dividing your plants. Dividing perennials not only rejuvenates them but also helps control their size, encourages vigorous growth, and gives you more plants to spread around your garden or share with friends. Here’s a step-by-step guide to dividing perennials in spring, along with tips to ensure success.
Why Divide Perennials in Spring?
Dividing perennials involves splitting mature plants into smaller sections, each with roots and shoots, to replant elsewhere. Spring is ideal for this task because plants are just waking up from dormancy, the soil is warming, and there’s plenty of time for roots to establish before summer heat arrives. Benefits include:
Healthier Plants: Dividing reduces overcrowding, improves air circulation, and prevents root competition, leading to stronger growth.
More Blooms: Many perennials, like daylilies or irises, bloom less when overcrowded. Dividing restores their vigor.
Free Plants: You’ll create new plants to fill gaps in your garden or swap with fellow gardeners.
Garden Control: Keep aggressive spreaders, like bee balm or phlox, in check by dividing them regularly.
When to Divide Perennials
The best time to divide most perennials is early spring, just as new growth emerges but before plants are in full leaf. Aim for a cool, cloudy day to minimize stress on the plants. However, not all perennials should be divided in spring.
Spring Division: Best for late-summer or fall bloomers like asters, hostas, daylilies, coneflowers, and sedum.
Avoid Spring Division: Early bloomers like peonies, columbine, or bleeding hearts are better divided in fall to avoid disrupting their flowering cycle.
Check your plant’s specific needs, but a general rule is to divide every 3–5 years or when you notice reduced flowering, crowded clumps, or a “dead” center in the plant.
How to Divide Perennials: Step-by-Step
Prepare Your Tools and Space
Gather a sharp spade or garden fork, a trowel, pruning shears, and a bucket of water. Clean and sterilize tools to prevent disease spread. Water the plants a day before to soften the soil and hydrate roots.
Dig Up the Plant
Dig around the plant’s drip line (the outer edge of its foliage), about 6–12 inches from the center, to capture as many roots as possible. Lift the clump gently with a fork or spade, shaking off excess soil to expose the roots.
Divide the Clump
Depending on the plant’s root system, you can divide it in different ways:
Loose, Fibrous Roots (e.g., hostas, daylilies): Gently pull apart sections by hand or use a sharp knife to cut through the crown.
Tough, Woody Roots (e.g., ornamental grasses): Use a spade or saw to slice the clump into smaller pieces.
Rhizomes or Tubers (e.g., irises, dahlias): Cut apart rhizomes with a knife, ensuring each section has at least one growth point or “eye.” Each division should have 3–5 healthy shoots and a good portion of roots.
Trim and Inspect
Trim away any damaged, dead, or overly long roots. Cut back foliage by about one-third to reduce stress on the plant. Inspect for pests or signs of disease, discarding any unhealthy sections.
Replant Promptly
Replant divisions immediately to prevent roots from drying out. Dig a hole twice as wide as the root ball and as deep as the roots. Place the division so the crown sits at soil level, spread the roots, and backfill with soil. Water thoroughly to settle the soil.
Care After Planting
Keep the soil consistently moist (but not waterlogged) for the first few weeks. Add a 1–2 inch layer of mulch to retain moisture and suppress weeds. Avoid fertilizing right away; let the plant focus on root establishment first.
Tips for Success
Label Your Plants: If you’re dividing multiple varieties, label them to avoid confusion.
Work Quickly: Roots exposed to air can dry out, so keep divisions in a bucket of water or covered with a damp cloth if you can’t replant immediately.
Improve Soil: Mix compost or well-rotted manure into the planting hole to give divisions a nutrient boost.
Space Properly: Check the mature size of your perennial and space divisions accordingly to avoid future overcrowding.
Divide in Moderation: Don’t over-divide; each section needs enough roots and shoots to thrive.
Popular Perennials to Divide in Spring
Here are some common perennials that benefit from spring division, along with specific tips:
Daylilies: Divide every 3–5 years. Each division should have a fan of leaves and healthy roots.
Hostas: Cut through the crown with a sharp knife. Larger divisions establish faster.
Irises: Divide rhizomes after flowering, ensuring each section has a healthy rhizome and fan.
Coneflowers: Divide every 4 years to maintain vigor. Keep at least 2–3 shoots per division.
Sedum: Easily divided by cutting through the root ball. Replant shallowly to avoid rot.
Troubleshooting Common Issues
Wilting After Division: This is normal as the plant adjusts. Keep soil moist and provide shade for a few days.
No Blooms the First Year: Some perennials focus energy on roots rather than flowers after division. Be patient!
Rotting Roots: Ensure good drainage and avoid planting too deeply.
Final Thoughts
Dividing perennials in spring is a rewarding task that keeps your garden vibrant and flourishing. With a little planning and care, you’ll enjoy healthier plants, more blooms, and the satisfaction of expanding your garden for free. So grab your shovel, pick a cool spring morning, and give your perennials the TLC they deserve.
