I used to be nervous about dividing my perennials, but once I gave it a try, I was hooked. Some plants actually bloom better and grow stronger after being split up—like they needed a little breathing room.
Over the years, I’ve learned which ones love it and which ones would rather be left alone. If you’re wondering what to divide (and what not to touch), this list will save you a lot of guesswork.
Your garden might just thank you with an even bigger show next season.
1. Black-Eyed Susan
These sunny golden bloomers practically beg to be divided every 3-4 years. Without division, the centers start to die out, leaving you with a donut-shaped plant that produces fewer flowers.
After splitting them up, you’ll notice more vigorous growth and an explosion of those cheerful daisy-like blooms. Fall or early spring works best for dividing these hardy perennials, and they’ll thank you with a spectacular show the following summer.
2. Daylily
Nothing signals the need for division quite like daylilies that have stopped flowering abundantly. When these reliable workhorses form dense clumps, they compete with themselves for nutrients and moisture.
Digging up and separating them every 3-5 years rejuvenates the plants completely. The outer sections typically perform best when replanted. Even better, each division quickly grows into a full-sized flowering plant, giving you free plants to spread throughout your garden!
3. Bearded Iris
Those magnificent ruffled blooms start to diminish when bearded iris rhizomes become overcrowded. The telltale sign is decreased flowering and a congested mat of rhizomes pushing up out of the soil.
Every 3-4 years, lift these beauties after flowering and cut the rhizomes apart, keeping only the newest portions with healthy fans of leaves. Replant them with the top of the rhizome exposed to sunlight. You’ll be rewarded with a spectacular rainbow of blooms!
4. Hostas
When spring reveals hostas that have grown into massive mounds, it’s division time! These shade-loving favorites actually benefit tremendously from being split every 4-5 years, especially if the center starts looking sparse.
Early spring is perfect for digging up the entire clump and cutting it into sections with a sharp spade. Each piece needs at least one growing point. The rejuvenated divisions will quickly establish and produce those beautiful mounds of distinctive foliage that make hostas so beloved.
5. Yarrow
Few perennials respond as dramatically to division as yarrow. After about 3 years, these drought-tolerant beauties start to lose vigor at the center, producing fewer of those flat-topped flower clusters that pollinators adore.
Spring division works wonders – simply dig up the entire plant and pull apart the outer sections, discarding the tired middle. The divisions establish quickly and will reward you with stronger stems, more abundant blooms, and that silvery, aromatic foliage that makes yarrow such a garden standout.
6. Coreopsis
Those cheerful daisy-like blooms start to diminish when coreopsis gets overcrowded. After about 2-3 years, you’ll notice the centers becoming woody and producing fewer flowers – a clear signal it’s time for division!
Spring is ideal for digging up these sunshine-loving perennials and gently pulling the clumps apart. The rejuvenated sections quickly establish and will bloom more profusely than before. As a bonus, dividing helps prevent these enthusiastic growers from spreading too aggressively throughout your garden beds.
7. Astilbe
When those feathery plumes start diminishing in size and number, your astilbes are crying out for division. These shade-tolerant beauties form dense root masses that eventually choke themselves out after 3-4 years of growth.
Early spring division works wonders – simply lift the entire clump and separate it into smaller sections with a sharp knife. Each division should have several growing points. The rejuvenated plants will quickly establish and produce more abundant and colorful plumes than before.
8. Garden Phlox
After several seasons, the centers of garden phlox clumps start to decline, producing fewer of those fragrant summer blooms. Division every 3-4 years keeps these cottage garden classics performing at their peak while helping prevent powdery mildew issues.
Early spring is perfect for lifting and dividing these beauties. Replant only the vigorous outer sections with healthy root systems. The rejuvenated divisions will establish quickly and reward you with more abundant flowering and better disease resistance than their overcrowded predecessors.
9. Shasta Daisy
Those iconic white daisies with sunny centers start to diminish when plants become congested. After about 3 years, Shasta daisies develop woody centers that produce fewer blooms – the perfect signal it’s division time!
Spring division works wonders for these summer bloomers. Simply dig up the entire clump and separate the vigorous outer sections, discarding the tired middle. The rejuvenated divisions establish quickly and will produce stronger stems and more abundant flowers than before, bringing that classic daisy charm back to your garden.
10. Coral Bells
When your coral bells (Heuchera) start lifting themselves out of the ground and flowering less vigorously, they’re signaling it’s division time. These colorful foliage plants benefit from being split every 3-4 years to maintain their vigor and distinctive leaf patterns.
Early spring is perfect for lifting and dividing these woodland natives. Each division should have several growing points and healthy roots. The rejuvenated plants will quickly establish and produce more abundant flowering stems and that stunning foliage that makes coral bells such garden standouts.
11. Asters
Those spectacular fall blooms start to diminish when asters become overcrowded. After about 3 years, you’ll notice fewer flowers and leggier growth – clear signals it’s time to divide these autumn stars!
Spring division works wonders for asters. Simply dig up the entire clump and separate it into smaller sections, each with several growing points. The rejuvenated divisions establish quickly and will reward you with more compact growth, stronger stems, and a more spectacular fall display than their congested predecessors.
12. Bee Balm
When bee balm starts producing fewer of those shaggy, colorful blooms that pollinators adore, it’s crying out for division. These enthusiastic spreaders form dense mats that eventually choke themselves out after 2-3 years of growth.
Spring division rejuvenates these native beauties completely. Dig up the entire patch and separate the vigorous outer sections, discarding the tired middle. The divisions establish quickly and will reward you with more abundant flowering and better resistance to powdery mildew than their overcrowded predecessors.
13. Siberian Iris
Unlike their bearded cousins, Siberian irises form dense clumps that eventually flower less profusely as they compete with themselves for resources. The telltale sign is a diminishing number of those elegant blooms rising above the grassy foliage.
Every 3-4 years, these beauties benefit tremendously from division. Early fall works best – simply lift the entire clump and separate it with a sharp spade. The rejuvenated divisions establish quickly and will produce more abundant flowering than their congested predecessors.
14. Sedum
When those succulent rosettes in the center start to die out, leaving a donut-shaped plant, your sedums are begging for division! These drought-tolerant beauties benefit from being split every 3-4 years to maintain their attractive form and abundant flowering.
Spring division works wonders for sedums. Simply dig up the entire clump and separate the vigorous outer sections. The rejuvenated divisions establish quickly in well-drained soil and will reward you with more compact growth and spectacular late-summer to fall blooms that pollinators absolutely adore.
15. Ornamental Grasses
When the centers of ornamental grass clumps start dying out, creating unsightly bare spots, it’s division time! Most varieties benefit tremendously from being split every 3-4 years to maintain their attractive form and vigorous growth.
Early spring works best for dividing these garden workhorses. Simply dig up the entire clump and cut it into sections with a sharp spade. The rejuvenated divisions establish quickly and will reward you with more upright growth, better fall coloration, and those spectacular seed heads that add winter interest.
16. Lamb’s Ear
Those velvety silver leaves start losing their charm when lamb’s ear becomes overcrowded. After 2-3 years, the centers often die out, leaving bare patches in what should be a lush carpet of touchable foliage.
Spring division works wonders for these tactile favorites. Simply dig up sections and replant the healthiest pieces with strong root systems. The rejuvenated divisions establish quickly in well-drained soil and will form those attractive rosettes of soft, fuzzy leaves that make lamb’s ear such a garden standout.
17. Peonies
Unlike most perennials, peonies strongly prefer to be left undisturbed for decades. These long-lived beauties can happily bloom for 50+ years without division! When disturbed, they often sulk for years before returning to full flowering.
If absolutely necessary (like rescuing or moving), divide peonies in early fall, making sure each division has 3-5 eyes (growth buds) and plenty of roots. Plant them at exactly the same depth they were growing before – too deep and they won’t flower. Patience is essential as they reestablish.
18. Baptisia
False indigo develops an enormous taproot that absolutely despises being disturbed. These prairie natives can live for decades without division and actually perform better when left completely alone to establish their deep root systems.
Attempting division often kills the plant or sets it back severely for years. The taproot makes division extremely difficult and traumatic for the plant. If you need more plants, collect and sow the abundant seed instead. Your patience will be rewarded with those spectacular spires of lupine-like blooms year after year.
19. Butterfly Weed
Despite being in the easily-divided milkweed family, butterfly weed develops a deep taproot that strongly resists division. These monarch butterfly magnets perform best when left undisturbed to establish their substantial root systems over many years.
Attempting to divide butterfly weed often results in plant death or years of recovery with minimal flowering. If you want more of these orange beauties, collect and sow the seeds instead. The established plants will reward your hands-off approach with abundant blooms that attract butterflies and beneficial insects.
20. Russian Sage
Those aromatic silver stems topped with lavender-blue flowers come from a woody base that strongly resists division. Russian sage develops extensive roots that don’t appreciate being disturbed once established in their sunny, well-drained location.
Attempting division often results in plant loss or years of recovery with minimal flowering. If you need more plants, take softwood cuttings in early summer instead. The established plants will reward your non-disruptive approach with that spectacular silver-blue haze that makes Russian sage such a standout in hot, dry gardens.