Have you ever stood in your garden, looking at a gorgeous perennial and wondering if you could divide it to create more plants?
While division works wonderfully for many perennials like hostas and daylilies, there are quite a few popular garden favorites that simply won’t cooperate with this approach.
But what makes some perennials impossible to divide, exactly?
The answer often lies beneath the soil surface. Plants with deep taproots, woody bases, or extremely brittle root systems resist division attempts – and for good reason.
These root structures have evolved to serve specific purposes, whether it’s accessing deep water sources, storing energy, or anchoring the plant against strong winds.
Today, we’ll explore 15 beautiful perennials that you’ll want to propagate using alternative methods, along with practical guidance on how to successfully multiply these garden gems.
1. False Indigo (Baptisia australis)
Alternative propagation method: Seed starting or stem cuttings
If you’re looking for a showstopper that delivers months of blue blooms followed by architectural seed pods, false indigo should be on your list. This North American native develops multiple sturdy stems that might fool you into thinking division would be simple. However, beneath that bushy appearance lies an extensive taproot system that can extend several feet into the ground.
False indigo invests heavily in root development during its first few years, which explains why young plants might seem slow to establish. Once mature, though, these plants become incredibly drought-tolerant and long-lived – some specimens can thrive for decades without any intervention.
For propagation, collect the dark seeds from the rattling pods in late fall. The seeds have hard coats, so you can either scarify them manually or plant them in fall to let winter’s freeze-thaw cycles do the work naturally. Stem cuttings taken in early summer will also root, though they may take a full season to establish properly. North Carolina State University
2. Burning Bush or Dittany (Dictamnus albus)
Alternative propagation method: Seed starting
Here’s a perennial that might not be on your radar yet, but it deserves serious consideration. Also called gas plant or fraxinella, this European native produces elegant spikes of white, pink, or purple flowers that emit such volatile oils they can briefly ignite on calm summer evenings – hence the dramatic common name.
Dittany develops a substantial taproot that makes it incredibly long-lived once established. Plants can flourish for 50 years or more without disturbance, but they absolutely hate being moved or divided. The flowers appear in late spring to early summer, followed by attractive star-shaped seed capsules.
If you want more plants, patience is your friend. Collect fresh seeds in late summer and sow them immediately, as they lose viability quickly. Germination can be slow and irregular, and seedlings may take 3-4 years to reach flowering size. However, the wait is worthwhile for such a distinctive and durable perennial. Missouri Botanical Garden
3. Lavender (Lavandula species)
Alternative propagation methods: Stem cuttings or layering
While lavender doesn’t have a traditional taproot, its compact, woody root system strongly resists division attempts. The fibrous roots form a tight network around the plant’s woody base, and disturbing this structure often leads to transplant shock or plant death.
Lavender’s Mediterranean origins show in its preference for well-drained soil and minimal root disturbance. Mature plants develop thick, woody stems at the base that become increasingly brittle with age, making division even more challenging.
Fortunately, lavender propagates beautifully from cuttings. Take 4-6 inch pieces from non-flowering shoots in early summer, remove the lower leaves, and root them in a well-draining potting mix. You can also try layering – simply bury a low-growing branch while it’s still attached to the parent plant, and roots will develop at the buried nodes within a few months.
4. Bleeding Heart (Dicentra spectabilis)
Alternative propagation methods: Stem cuttings or root cuttings
Those graceful, arching stems covered in heart-shaped flowers make bleeding heart a cottage garden essential. While these plants don’t have taproots, they possess something equally challenging for division: brittle, sap-filled roots that break easily and don’t recover well from damage.
Bleeding hearts naturally form larger clumps over time, so you might be tempted to dig up half the plant for transplanting. However, the roots are so fragile that this approach often fails, leaving you with a damaged original plant and unsuccessful divisions.
Instead, try taking stem cuttings from non-flowering shoots in late spring. These root readily in moist potting mix. You can also carefully take root cuttings in fall when the plant is dormant – pieces of thick root about 2-3 inches long will develop into new plants when planted vertically with the top end just below soil level.
5. Evening Primrose (Oenothera macrocarpa)
Alternative propagation methods: Seed starting or plantlet separation
Evening primrose might seem like an unusual choice for ornamental gardens, but if you’ve never experienced its intoxicating fragrance on a summer evening, you’re missing something special. The large, yellow flowers open at dusk and release a sweet scent that can perfume an entire garden area.
This plant develops a substantial taproot, but it also produces horizontal runners that create new plantlets around the mother plant. Rather than attempting to dig up the main taproot, wait for these natural offsets to develop their own root systems, then carefully separate them using a sharp knife.
Seeds are another excellent option. Collect them from the dried capsules in fall and either plant immediately or store them for spring sowing. The seeds don’t need special treatment and germinate readily in ordinary garden soil.
6. Columbine (Aquilegia species)
Alternative propagation method: Seed starting
Columbines possess a combination of fibrous roots and a central taproot that makes division difficult and often unsuccessful. But here’s the wonderful thing about these cottage garden favorites – they’re such enthusiastic self-seeders that you rarely need to worry about making more plants.
The distinctive spurred flowers come in an amazing range of colors and combinations, from deep purple and blue to pink, white, and yellow. After blooming, the plants produce small pods filled with glossy black seeds that scatter naturally if left undisturbed.
For controlled propagation, collect seeds just as the pods begin to split open in midsummer. Sow them immediately in a cold frame or protected area, as fresh seeds germinate much better than stored ones. Seedlings will appear the following spring and bloom in their second year. While hybrid varieties won’t come true to type, the results are often delightfully surprising. University of Wisconsin Extension
7. Sage (Salvia officinalis)
Alternative propagation methods: Stem cuttings or layering
Like other Mediterranean herbs, sage develops a woody base as it matures, making division increasingly difficult with age. The plant’s root system is designed for stability and drought tolerance rather than easy propagation, so attempting to split mature plants often results in shock or death.
Sage varieties offer incredible diversity, from the classic gray-green culinary type to purple, golden, and variegated ornamental forms. All share the same growth habit and propagation preferences.
Softwood cuttings taken in late spring or early summer root easily in well-draining potting mix. You can also layer low-growing branches by covering them with soil while they remain attached to the parent plant. Within a few months, roots will develop at the covered nodes, and you can sever the new plants from the original.
8. Rosemary (Rosmarinus officinalis)
Alternative propagation methods: Stem cuttings or layering
Another woody Mediterranean herb, rosemary forms an extensive root system that strongly resists disturbance. The plant’s needle-like leaves and aromatic oils help it survive in harsh, dry conditions, but these same adaptations make it intolerant of root disruption.
Rosemary cuttings root readily in spring and summer. Take 4-6 inch pieces from the current year’s growth, strip the lower needles, and place them in a well-draining rooting medium. Keep them consistently moist but not waterlogged, and you should see roots developing within 6-8 weeks.
Layering works well too, especially with prostrate varieties that naturally trail along the ground. Simply pin a flexible branch to the soil surface and cover the middle section with compost or potting mix, leaving the tip exposed.
9. Foxtail Lily (Eremurus species)
Alternative propagation method: Seed starting (patience required)
These spectacular spikes of densely packed flowers can reach 6 feet tall, creating dramatic vertical accents in the garden. The flowers emerge from ground level in late spring, rising like colorful rockets above the surrounding perennials.
Below ground, foxtail lilies develop unique octopus-like root systems with thick, fleshy roots radiating from a central crown. This root structure is extremely brittle and doesn’t divide successfully. Even minor damage during transplanting can kill the plant.
Seeds offer the best propagation method, though you’ll need patience. Collect fresh seeds from the dried flower spikes in late summer and sow them immediately in a cold frame. Germination can be irregular, and seedlings may take 4-5 years to reach blooming size. However, established plants are incredibly long-lived and will produce more flower spikes as they mature.
10. Sea Holly (Eryngium species)
Alternative propagation methods: Seed starting or root cuttings
With their spiky blue or silver flowers and architectural form, sea hollies add unique texture to perennial borders. These plants develop deep taproots that help them access moisture in their native coastal habitats, but this makes traditional division nearly impossible.
Sea holly flowers are magnets for beneficial insects, particularly hoverflies and native bees. The blooms retain their color and structure well into autumn, providing late-season interest when many other perennials have finished their show.
For propagation, collect seeds from the dried flower heads in fall and sow them immediately, as they need a cold period for germination. Some species also respond well to root cuttings taken in late fall – pieces of thick root about 2 inches long can be planted vertically in a cold frame.
Interestingly, some sea holly species do produce plantlets around the base of mature plants, and these can sometimes be carefully separated with their own roots intact. However, this natural division should only be attempted if you can clearly see independent root systems on the offsets. The Morton Arboretum
11. Lavender Cotton (Santolina chamaecyparissus)
Alternative propagation methods: Stem cuttings or layering
Despite its common name, lavender cotton is neither lavender nor cotton – it’s a Mediterranean perennial prized for its silvery, aromatic foliage and button-like yellow flowers. Like true lavender, it develops a woody base that resists division and prefers minimal root disturbance.
The plant forms neat, compact mounds that work beautifully as edging or in herb gardens. The feathery, gray-green leaves release a pleasant, camphor-like scent when brushed or crushed, and they retain their color through winter in mild climates.
Cuttings taken from new growth in late spring or early summer root readily in sandy potting mix. The plant also layers naturally where branches touch the ground, making it easy to propagate without disturbing the parent plant.
12. Balloon Flower (Platycodon grandiflorus)
Alternative propagation method: Seed starting
Those inflated buds that give balloon flower its charming name open into star-shaped blooms in shades of blue, pink, or white. The flowers appear continuously from midsummer through early fall, making this one of the most reliable late-season bloomers.
Beneath the attractive foliage, balloon flowers develop thick, fleshy roots that resemble small turnips. These storage roots help the plant survive adverse conditions but make division extremely difficult. The roots are brittle and full of milky sap, and damage to the root system often proves fatal.
Seeds germinate easily when sown in fall or early spring. Fresh seeds give the best results, so collect them from the dried seed pods in autumn and sow immediately. Seedlings typically bloom in their second year and will often self-seed once established.
13. Fall Anemone (Anemone hupehensis)
Alternative propagation method: Seed starting
Just when most perennials are winding down for the season, Japanese anemones burst into bloom with masses of delicate pink or white flowers. These late bloomers are invaluable for extending garden color into autumn, and they perform well in partial shade where many other flowering perennials struggle.
Fall anemones develop substantial taproots that can extend deep into the soil, making division impossible without destroying the plant. However, they’re generous self-seeders, producing fluffy seed heads that look remarkably like cotton candy.
Collect the seeds just as the cottony seed heads begin to expand in late fall. The seeds can be sown immediately in a cold frame or saved for spring planting. Fresh seeds germinate much more readily than stored ones, so don’t delay if you want the best results.
14. Baby’s Breath (Gypsophila paniculata)
Alternative propagation method: Seed starting
The clouds of tiny white, pink, or purple flowers make baby’s breath a classic choice for cutting gardens and cottage garden borders. Despite its delicate appearance above ground, this plant develops an surprisingly robust taproot system that can extend several feet deep.
This extensive root development allows baby’s breath to thrive in poor, dry soils where other plants might struggle. However, it also makes the plant nearly impossible to divide successfully and extremely sensitive to transplanting.
Seeds are readily available and germinate well when sown in spring or fall. The plants are typically biennial or short-lived perennial, so regular seed sowing ensures a continuous supply. Keep in mind that baby’s breath is considered invasive in some areas, so check local regulations before planting.
15. Lupine (Lupinus species)
Alternative propagation method: Seed starting
Those dramatic spikes of densely packed flowers in shades of blue, purple, pink, white, and yellow make lupines standout performers in the early summer garden. The palmate leaves and sturdy flower spikes create excellent vertical accents among lower-growing perennials.
Lupines develop substantial taproots that can reach impressive depths, allowing them to access nutrients and moisture that shallow-rooted plants can’t reach. This root system makes division impossible and transplanting extremely difficult.
Seeds offer the most reliable propagation method, though they require some preparation. Lupine seeds have hard, waxy coats that benefit from scarification – either nick them with a file or soak them in warm water overnight before planting. Cold stratification also improves germination, so fall sowing often gives better results than spring planting.
