11 Plants You Should Never Divide, According to Gardening Experts

lavender flowers — Credit:
ASIFE / GETTY IMAGES

Plant division is a propagation technique used to multiply plants, control plant size, and prevent overcrowding. While it is often a necessary step for plants that grow in clumps or have tubers or rhizomatous root systems, not all plants can handle being divided. The process involves digging up the plants and separating them into smaller sections, which can be too disruptive for plants with tap roots or woody perennials. Ahead, gardening experts share which plants you should never divide—and why.

Edwin Dysinger, expert gardener and co-founder of Seedtime, a leading garden planning and management app
Adrienne Roethling head gardener for a private estate and former curator of Juniper Level Botanic Gardens at Plant Delights Nursery

01 of 11

Milkweed

Typically, plants with taproots don't take well to division. Milkweed (Asclepias spp.), a North American native perennial, falls into this category. "Milkweed has a long single tap root," says Edwin Dysinger, expert gardener and co-founder of Seedtime. "It is best propagated by seed or through cuttings from the stem."

02 of 11

Butterfly Weed

A relative of milkweed, butterfly weed (Asclepias tuberosa) is an exceptionally easy plant to grow, but it doesn't tolerate division well. "Butterfly weed does not like its roots disturbed and has a hard time recovering if disturbed," says Adrienne Roethling, head gardener for a private estate. "The best way to gain multiple plants is to collect seeds. Seed pods resemble skinny, short bean pods. Once they split, the individual seeds disperse with their dandelion-like structures. The hairy seeds carry well with the wind, and almost all seeds will germinate into a new plant."

03 of 11

Baby's Breath

Baby's breath (Gypsophila paniculata) is a beautiful, whimsical plant to grow in the garden. However, experts warn against disrupting baby's breath once it's established in your garden. "These are difficult to divide because of their single long taproot," says Dysinger. "They will do much better propagated by seed or cuttings."

04 of 11

Columbine

Columbine (Aquilegia spp.) self-seeds happily throughout the garden, which may lead to you relocating it if it pops up in an unsuitable location. But Dysinger recommends against moving this plant. "Many columbine species have either a tap root or a combination tap root and fibrous root system, making successful division difficult," he says, adding that they are easier to grow from seed.

05 of 11

False Indigo

False indigo (Baptisia spp.) is a legume, and plants in this family generally don't like being disturbed. According to Dysinger, the roots of false Indigo can grow as deep as 12 feet, making this plant difficult to move successfully. He recommends propagating it by seed or cuttings instead.

06 of 11

Balloon Flower

Balloon flower (Platycodon spp.) produces numerous fleshy tap roots that are easily damaged during division. "This plant self-propagates with vigor, sending out many new shoots that pop up in the spring," says Dysinger. He notes that while you may find dormant rootstock for sale, they are fragile and resistant to transplanting. "They do propagate easily from seed, as well as via nursery starts or stem cuttings," he says.

07 of 11

Sage

Close-up of a green plant with textured leaves — Credit:
Stefano Madrigali / Getty Images

Woody perennials, like sage (Salvia officinalis), don't handle division well. "Once established, it does not like to be disturbed," says Dysinger. "It can be propagated by seed or cutting, but cutting is probably the easiest and best method."

08 of 11

Lavender

Like sage, most species of lavender (Lavandula) form a woody stem with narrow, aromatic, evergreen leaves and purple flowers. Because it is a woody plant, lavender is difficult to divide. "If it does get to be a multi-stemmed shrub, it would be difficult to divide into multiple plants," Roethling says. "In addition, moving the plant could cause severe leaf drop and will be difficult to revive."

09 of 11

Rosemary

Rosemary (Salvia rosmarinus) is a resilient plant that is heat- and drought-tolerant, but it won't tolerate being divided. "Rosemary forms a multi-stemmed woody shrub. It would be difficult to get into the center of the plant to divide it," says Roethling, adding that the result could be fatal to the plant.

10 of 11

Clematis

Some species of clematis (Clematis spp.) form a woody stem, making them difficult to divide. "Most clematis have a finicky root system; the roots like shade and cooler soil while the tops thrive in full sun," says Roethling. "They really should be left alone, as trying to divide the roots to get more plants poses a challenge. The clematis may not rebound if disturbed."

11 of 11

Spurge

Shrubby evergreen form of Euphorbia with large heads of vivid greeny yellow flowers in spring. — Credit:
Penpak Ngamsathain / Getty Images

Spurge (Euphorbia) is made up of a large group of plants, ranging from herbaceous perennials to cacti and woody shrubs or trees, says Roethling. Many varieties spread quickly, and you may be tempted to divide the plants, but it's not recommended. "Most herbaceous spurge produce a thick tap root and don't like to be disturbed," she says. "More than likely, if the roots were divided, the plants will not recover even with the best efforts."