Dividing perennials is a tried-and-true gardening technique, but not every plant appreciates being split apart. Some perennials thrive best when left undisturbed, as dividing them can weaken their roots, disrupt growth, or even lead to their demise.
Here are 16 perennials that prefer to grow uninterrupted—saving you time and sparing your plants unnecessary stress.
1. Lavender
Lavender is a fragrant, shrubby herb prized for its essential oils. It attracts pollinators to the garden and develops a woody base over time. This Mediterranean native detests having its roots disturbed.
Avoid the temptation to divide mature lavender plants, as doing so will likely kill them. Instead, propagate lavender by taking stem cuttings.
Lavender thrives in full sun and well-draining soil. Prune it annually after flowering to maintain an attractive, compact shape. With the right growing conditions and care, lavender can live in your garden for a decade or more without division.
2. Butterfly Weed
Butterfly weed (Asclepias tuberosa) is a native wildflower that serves as a critical food source for monarch butterfly caterpillars. This clumping perennial features vibrant orange flowers that bloom from summer into fall. Butterfly weed grows a deep taproot that doesn’t tolerate being disturbed.
Attempting to dig up and divide the taproot will damage the plant and may cause it to die. Once established, butterfly weed is best left in place.
It’s a low-maintenance perennial that will slowly spread and self-sow in the right growing conditions. Instead of division, start new butterfly weed plants from seed.
3. Peonies
Peonies are old-fashioned favorites admired for their huge, ruffled blooms in pink, red, and white shades. These long-lived perennials resent having their roots disturbed and can sulk for years after transplanting or division. Peonies perform best when allowed to settle in and mature over time.
If you must move or divide a peony, do so in the fall and expect the plant to take two to three years to rebloom well afterward.
Peonies can live for 50 years or more when left to grow in peace. Enjoy their gorgeous flowers each spring and allow them to grow into sizable clumps.
4. Baptisia
Baptisia, also known as false indigo, is a native prairie plant with spires of blue, purple, yellow, or white flowers in early summer. This shrub-like perennial develops a deep taproot and doesn’t divide well.
Baptisia resents root disturbance and can take several years to reestablish after transplanting.
Once established, baptismia’s extensive root system makes it very drought-tolerant. Allow baptismia to form a large clump over time, as bigger plants produce more of the showy flower spikes. It also fixes nitrogen in the soil, making it a great companion plant in the perennial garden.
5. Euphorbia
Euphorbia is a diverse genus of plants. Some make excellent perennials for sunny, dry areas. However, many euphorbias contain a milky sap that can irritate skin. Digging and dividing euphorbias causes this sap to flow, potentially exposing you to the irritant. It’s best to allow established euphorbias to grow undisturbed.
To propagate euphorbias, take basal cuttings in spring or remove rooted pieces from the edge of the clump. Some euphorbias self-sow readily, so you can collect and plant the seeds.
There’s a euphorbia for almost any sunny garden spot, with various foliage colors, textures, and forms available.
6. Hellebores
Hellebores, called Lenten roses, are some of the first perennials to bloom in late winter and early spring. These evergreen plants have attractive, leathery leaves and nodding cup-shaped flowers in various colors. Hellebores grow very slowly and dislike being moved or divided.
It can take a hellebore seedling two to three years to reach flowering size. Mature clumps can eventually spread to 2 feet wide or more.
Once your hellebores are established, allow them to grow undisturbed to reach their full potential. Over time, hellebores will gently self-sow around the garden.
7. Columbine
Columbines are short-lived perennials with delicate, nodding flowers that float above lacy blue-green foliage. These spring bloomers set seed prolifically, so they move around the garden yearly. Columbines grow from a woody taproot that doesn’t divide well. It’s better to allow your columbines to self-sow.
To encourage your columbines to self-sow where you want them, lightly scratch the soil right after they flower. This will create an ideal environment for the seeds to sprout.
Columbines are a charming addition to any spring garden, and they have various flower colors and forms available.
8. Bleeding Heart
Old-fashioned bleeding heart is a classic spring perennial with arching stems of dangling, heart-shaped flowers. This ephemeral plant goes dormant in summer, so it’s easy to accidentally dig up the roots. Bleeding heart grows from brittle, fleshy roots that bleed sap and don’t divide well.
It’s best to plant a bleeding heart and allow it to grow undisturbed. Mark its location so you don’t accidentally dig in the area while it’s dormant. Bleeding heart will slowly spread over time, forming a graceful clump.
Enjoy the romantic blooms in spring, then plant summer perennials around it that will fill the space later.
9. Goatsbeard
Goatsbeard is a bold perennial with creamy white plumes of flowers in early summer that resemble astilbe. This plant prefers moist, organic-rich soil and will slowly form an impressive clump. It grows a thick, woody rootstock that doesn’t respond well to division.
Once you have goatsbeard situated in your landscape, avoid moving or dividing it. The plant gets quite large, so give it plenty of space to mature.
Pair goatsbeard with other moisture-loving perennials like ligularia and rodgers for a lush planting. The flowers also make a unique addition to fresh bouquets.
10. Monkshood
Monkshood is an old-fashioned perennial with spikes of hooded purple flowers in the fall. Its parts are extremely poisonous, so it’s crucial to wear gloves when handling it.
The plant grows from a tuberous root that doesn’t tolerate disturbance. It’s best to plant monkshood and then leave it be. The clumps will gradually spread over time, but growth is slow.
Monkshood pairs well with other fall bloomers, such as asters and ornamental grasses. However, this toxic plant should be kept away from children and pets.
11. Delphiniums
Delphiniums are the early summer garden queens with towering blue, purple, pink, or white flower spikes. These short-lived perennials grow from a tuberous root that doesn’t divide easily. They often exhaust themselves after a few years, so starting new plants from seed is better.
They require staking to support their tall flower spikes and prevent wind damage. To encourage a second flush of blooms, cut the flower stalks back to the ground after the first round of flowers finishes.
With their showy flowers and stately form, delphiniums are worth a little extra effort.
12. Lupines
Lupines are another early summer favorite, with spires of pea-like flowers in a rainbow of colors. These plants grow from a deep taproot that doesn’t respond well to division. They are short-lived but will self-sow prolifically in the right conditions.
To encourage lupines to self-sow, leave some flower spikes in place to form seed pods.
The seeds have a hard coating, so nick or soak them before planting to speed germination. Lupines need excellent drainage and perform well in rock gardens or slopes.
13. Poppy
Poppies are a diverse group of plants, but most varieties don’t divide well due to their taproots. Oriental poppies go dormant in summer, so it’s easy to damage their roots accidentally while digging nearby.
Allow oriental poppies to form large clumps over time and mark their location so you don’t disturb them.
Iceland poppies are short-lived perennials that self-sow readily, so division isn’t necessary. California poppies are annuals that will come back year after year from seed. With a wide variety of colors and forms available, there’s a poppy for almost any sunny spot in your garden.
14. Russian Sage
Russian sage is a subshrub with airy spikes of lavender-blue flowers in late summer. This drought-tolerant plant thrives in hot, dry conditions and doesn’t like having its roots disturbed. It tends to flop open in the center as it matures.
Cut the stems back to 6 inches in early spring to rejuvenate an older plant. Avoid digging and dividing Russian sage, as this will likely kill it.
This plant pairs beautifully with other sun-loving perennials like coneflowers and black-eyed Susans.
15. Sea Holly
Sea holly is an architectural plant with spiny, silvery-blue foliage and thistle-like flowers in summer. This drought-tolerant perennial grows a deep taproot that doesn’t tolerate disturbance. It performs best in lean, sandy soil and will rot in heavy clay or overly moist conditions.
Give sea holly a sunny spot with excellent drainage, then leave it be.
The striking foliage and flowers work well in gravel gardens or rock gardens. Sea holly also makes an excellent cut flower, both fresh and dried.
16. Foxtail Lily
Foxtail lily (Eremurus) is an impressive perennial with towering spikes of bottlebrush flowers in early summer. This plant grows from a starfish-shaped rootstock that doesn’t divide well. It is prone to crown rot, so excellent drainage is necessary.
Plant the foxtail lily in a sunny spot with lean, well-drained soil and allow it to mature over time. In ideal conditions, the flower spikes can reach up to 8 feet tall.
Foxtail lily pairs well with ornamental alliums and makes a spectacular cut flower.
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Nancy has been a plant person from an early age. That interest blossomed into a bachelor’s in biology from Elmira College and a master’s degree in horticulture and communications from the University of Kentucky. Nancy worked in plant taxonomy at the University of Florida and the L. H. Bailey Hortorium at Cornell University, and wrote and edited gardening books at Rodale Press in Emmaus, PA. Her interests are plant identification, gardening, hiking, and reading.