Dividing and Transplanting Perennials Safely in August
August is an ideal time to refresh your perennial beds by dividing and transplanting established plants. As summer fades but before cooler autumn weather sets in, many perennials pause their top growth and focus energy on growing healthy roots—making it the perfect window for moving, splitting, and rejuvenating your garden.
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Why Divide and Transplant Perennials in August?
- Rejuvenate tired clumps: Older perennials often flower less and get crowded or bare in the center.
- Expand your garden: Turn one mature plant into several—perfect for filling new beds or sharing with friends!
- Refresh soil and reduce pests: Dividing breaks up congested roots and exposes hidden slugs or vine weevils.
- Give divisions time: Warm soil in late summer helps new plants establish roots before winter.
Which Perennials Should You Divide Now?
- Most summer- and autumn-flowering perennials:
- Daylily (Hemerocallis)
- Iris
- Shasta daisy
- Rudbeckia
- Hostas
- Phlox
- Coreopsis
- Crocosmia
- Asters
- Spring-flowering perennials (like peony or hardy geranium) are best divided in early spring or after autumn bloom.
Step-by-Step Guide to Safe August Division
- Prep and Water:
Water the plant and surrounding bed a day before to ease digging and reduce shock. - Lift Carefully:
Use a garden fork to dig around the plant—start wide, then loosen the soil and ease out the whole clump. - Divide:
- Pull clumps apart by hand for loosely rooted plants.
- For tightly packed roots, slice down the middle with a sharp spade or cut with a knife.
- Keep several shoots and roots on each new division.
- Trim and Clean:
Remove damaged or dead roots, old stems, and weeds. - Replant Promptly:
- Dig a hole twice as wide as the root ball.
- Set division at the same soil level as before.
- Water in well and mulch to keep moisture around the roots.
- Aftercare:
- Water regularly for the next month, especially in dry spells.
- Shade new divisions for a few days if August is hot.
Extra Tips
- Work early or late in the day—not during blazing midday sun.
- Don’t divide if the soil is bone dry or in a heatwave; wait until after a rain if possible.
- Label your new plants!
By dividing and transplanting in August, you keep borders healthy, prevent overcrowding, and enjoy even bigger, brighter displays next year. It’s one of the most satisfying (and economical) garden jobs of the season.