September brings the perfect weather for Pennsylvania gardeners to divide and transplant perennials before winter sets in. Splitting overcrowded plants not only keeps your garden healthy but also gives you free new plants to expand your garden or share with friends.
With cooler temperatures and typically more rainfall, your divided perennials will have time to establish roots in their new locations before frost arrives.
1. Choose The Right Time
Early September mornings or evenings provide ideal conditions for dividing perennials in Pennsylvania. The soil remains warm while air temperatures cool down, reducing transplant shock.
Avoid dividing on hot, sunny days which can stress newly exposed roots. Work on overcast days or when rain is in the forecast to give your plants natural watering assistance.
Most spring and summer bloomers respond well to fall division, while fall bloomers should wait until spring.
2. Pick Proper Candidates
Look for perennials that have formed dense clumps, spread beyond their boundaries, or developed dead centers – these are prime division candidates. Hostas, daylilies, black-eyed Susans, and coneflowers typically respond wonderfully to September division in Pennsylvania.
Skip any plants showing signs of disease or pest problems. Dividing stressed plants can kill them rather than rejuvenate them.
Woody perennials like lavender and Russian sage generally don’t divide well, so leave these intact.
3. Gather Essential Tools
Sharp spades and garden forks make lifting established perennial clumps much easier. For tough root systems, keep pruning shears or a serrated knife nearby to slice through stubborn connections.
Prepare a bucket of water to rinse roots if needed, making divisions clearer to see. Have fresh compost ready to amend both the original planting hole and new transplant locations.
Don’t forget a tarp for placing divided sections and keeping your work area organized as you go.
4. Water Plants Thoroughly
Soak your perennials deeply the day before dividing them. Well-hydrated plants experience less shock and their root systems separate more easily when moist.
Morning watering works best, allowing plants to absorb moisture throughout the day before tomorrow’s division. For clay-heavy Pennsylvania soils, this pre-watering helps loosen the ground, making digging less strenuous.
Avoid dividing during drought conditions unless you can provide consistent aftercare watering.
5. Dig With Care
Start digging about 6 inches from the plant’s drip line, working in a circle to minimize root damage. Pennsylvania’s varied soil types might require different approaches – rocky soils need more careful work than loamy areas.
Gently pry upward with your garden fork after loosening the soil all around. For large established clumps, you may need to dig deeper to get under the main root mass.
Lift the entire plant if possible rather than removing portions while it remains in the ground.
6. Make Clean Divisions
Once lifted, shake or rinse excess soil to reveal natural division points in the root system. Some perennials like daylilies and hostas can be pulled apart by hand into smaller clumps with 3-5 shoots each.
Tougher roots may require cutting with a sharp knife or spade. Always make clean cuts to prevent disease entry points and promote faster healing.
Remove any dead or damaged sections, keeping only healthy portions with strong roots and several growth points.
7. Replant Promptly With Amendments
Don’t let divided perennials dry out – replant them within an hour of division if possible. Prepare new planting holes twice as wide as each root ball and mix in compost to refresh Pennsylvania’s often clay-heavy soils.
Position plants at the same depth they were growing previously, with crown just at soil level. Spreading roots outward rather than circling them gives plants a stronger foundation.
Firm soil gently around new plantings to eliminate air pockets without compacting too much.
8. Provide Attentive Aftercare
Water newly transplanted divisions deeply and consistently for the first three weeks. Pennsylvania’s September weather can be unpredictable, so monitor rainfall and supplement as needed.
Apply a light mulch layer of shredded leaves or compost to retain moisture and insulate roots as temperatures fluctuate. Avoid fertilizing right away – wait until spring to prevent tender new growth that could be damaged by winter.
Mark new plantings clearly so you don’t accidentally step on them or forget their locations come spring.