Divide These Five Perennials in August for
Gardening Know How recommends dividing bearded iris, Shasta daisies, common yarrow, hostas, and daylilies in August to rejuvenate plants and propagate new
August is an ideal time to divide overgrown perennials as cool nights and warm soil encourage quick root regrowth. Dividing now gives you free plants for next year and tidier borders this fall.
Bearded Iris
Bearded iris (Iris germanica) features six petals, three upright, three drooping, and a frilly beard that attracts pollinators. It grows up to 4 feet tall and thrives in USDA zones 3-9 with well-draining, sandy soil and full sun. After several years, clumps become crowded and tangled, making August the perfect time to divide. Cut foliage to 6 inches, lift roots, divide, and replant with the rhizome top exposed.
Shasta Daisies
Shasta daisies (Leucanthemum x superbum) have white petals with yellow centers and dark green leaves. They grow in USDA zones 5-9, preferring sun to partial shade and well-draining soil. After 2-3 years, clumps get woody and flower poorly. Divide in late summer or early fall by digging up the clump, shaking off soil, discarding the worn center, and splitting the rest with a sharp knife. Replant sections at original depth.
Common Yarrow
Also known as gordaldo or milfoil, common yarrow (Achillea millefolium) has feathery leaves and flat clusters of tiny yellow, white, or pink blooms. Stems reach 3 feet tall. It grows in USDA zones 3-9, tolerating poor, clay, or sandy soil if well-draining. Plants benefit from division every few years when the center dies out. Dig up, discard the center, and replant outer chunks.
Hostas
Hostas are shade-loving perennials prized for their foliage, growing from rhizomatous roots in USDA zones 3-9. They prefer shade but tolerate dappled sun. By autumn, foliage may yellow, brown, or collapse. Divide on an overcast August morning, ensuring each section has healthy roots and shoots. Keep pieces damp and store for weeks before replanting.
Daylilies
Daylilies are drought-tolerant, pollinator-attracting perennials with trumpet-shaped blooms in red, orange, yellow, purple, and pink. They thrive in USDA zones 3-10 and outgrow their space every three to five years. Divide after flowering ends, usually late August. Clip foliage close to the ground, dig up the clump, separate root ball by hand, and replant with crown just below soil surface.
Teo Spengler, a master gardener and docent at the San Francisco Botanical Garden, authored the guide. She has over two decades of horticulture writing experience and splits her time between San Francisco and the French Basque Country.
