10 Plants You Should Never Grow in Clay Soil, Experts Say

A field with blooming lavender flowers — Credit:
Jose Gonzalez Buenaposada / Getty Images

Clay soil can be difficult for gardeners to work with because it is slow-draining and compacts easily, causing plants to suffer from root rot and other fungal diseases. While some plants can thrive in these boggy, compacted conditions, others will struggle to establish and may ultimately die. To save you time and money when planning your garden, we spoke to experts who shared a number of plants you should never grow in clay soil.

Tabar Gifford, partnership cultivator and master gardener at American Meadows
Alexander Betz, landscape designer and founder of Plant By Number

01 of 10

Lavender

Lavender (Lavandula) is native to the Mediterranean, where soils are rocky, alkaline, and well-draining, meaning its roots will rot in heavy clay. "In clay, water pools at the crown and around the roots, depriving them of oxygen and encouraging fungal pathogens," says Tabar Gifford, partnership cultivator and master gardener at American Meadows. "Within a single wet winter, you’ll often see root rot, yellowing foliage, and eventual collapse of the entire plant—no amount of pruning will save a lavender drowned in clay."

02 of 10

Beardtongue

Beardtongue (Penstemon) thrives in areas with dry, rocky soil that allows air to circulate around the crown. "In clay, water collects at the stem base, causing crown and root rot—you’ll notice stems collapsing at the soil line and leaves turning yellow or wilted," says Gifford. "Even the most robust penstemon cultivars cannot withstand prolonged soggy conditions."

03 of 10

Peony

Peonies in the garden — Credit:
Jasenka Arbanas / Getty Images

Peonies (Paeonia) will come back bigger and better every year if they're grown in well-draining soil, but these beloved perennials struggle in clay-based environments. "Peonies dislike being waterlogged, and clay soil retains too much moisture around the roots, leading to poor growth or rot," says landscape designer Alexander Betz. "Peonies do best in well-drained, loamy soil enriched with compost."

04 of 10

Tulips

If you planted tulips (Tulipa) last year and they didn't come up in spring, it may be because your soil is clay-based. "Tulip bulbs will rot in clay soil, as it tends to trap too much moisture around them during winter and spring," says Betz. "Light, well-drained soil with a slightly alkaline to neutral pH allows for best results."

05 of 10

Clematis

Clematis (Clematis spp.) is a vining plant that won't perform in clay. "Also vulnerable to root rot, clematis does not do well in damp, heavy clay soil," says Betz. "Plant in well-drained, rich, slightly alkaline soil that retains moisture but doesn’t become waterlogged."

06 of 10

Hostas

Frances Williams hosta — Credit:
Marina Kositsyna / Getty Images

While hostas (Hosta spp.) can tolerate some moisture, these shade-loving plants dislike constantly soggy soil, says Betz. He adds that clay's poor drainage causes hosta's roots to rot. For best results, grow these plants in rich, well-draining, slightly acidic or neutral soil.

07 of 10

Azaleas

Pink azalea bushes in bloom. — The flowering of the azaleas signals that spring is well under way. Credit: Van Hickman / EyeEm/Getty Images

Azaleas (Rhododendron) like moist environments, but they need the soil to be well-draining. Clay soil has a dense structure that prevents proper root spread and retains too much water, causing root rot, says Betz. To grow healthy, thriving azaleas, plant them in acidic, organic-rich soil with good aeration.

08 of 10

Russian Sage

Russian sage (Perovskia atriplicifolia) needs gritty, fast-draining soil to keep the base of the plant healthy. "In compacted clay, moisture lingers at the plant’s crown, leading to crown rot and a sudden flop of stems," says Gifford. "Even hardy varieties like 'Blue Jean Baby' will struggle—roots suffocate, and the plant loses its upright form and vigor."

09 of 10

Blanket Flower

Blanket flower (Gaillardia spp.) is native to prairies and sandy meadows. Its deep taproot searches for moisture in drought-prone soil. "When forced into heavy clay, that taproot cannot penetrate the dense ground, and the crown sits in a waterlogged pocket," says Gifford. "The result is suffocation of the root system, poor flower production, and rapid decline of foliage and blooms."

10 of 10

Prairie Zinnia

A low-growing, tap-rooted groundcover, prairie zinnia (Zinnia grandiflora) thrives in the dry, sandy plains of the American West. "Transplanted into clay, its roots struggle for oxygen, leading to chlorosis (yellowing leaves), stunted growth, and a failure to set buds," says Gifford. "Without quick drainage, prairie zinnia often becomes leggy, weak, and unrecognizable from its robust prairie origins."

10 Plants You Should Never Grow in Clay Soil, According to Gardening Experts