Clay soil is one of the most difficult conditions a gardener can face. Dense and slippery when wet, it's even more of a challenge as it bakes brick solid when dry. Clay particles are extremely small and tend to pack together, leaving no room for air or water movement. Not every plant is going to be able to grow in clay, but plenty can and some even help make clay soil better.
The first order of business for any gardener with clay soil is to improve the texture of the soil with organic matter.
Unfortunately, soil keeps trying to go back to its native state, so there is no one time fix. This will be an ongoing process, but the benefits will pay off in the long run. Generously amending or top dressing with compost, leaf mold, composted manure or other types of organic matter will gradually bulk up the texture of your soil, lessening the compaction.
Choosing plants to grow in clay soil takes some discretion. Certainly, plants that need a well-drained soil are not going to be happy growing in clay. Don't give up. There are plants that not only tolerate clay soil, many will also help break up and improve its texture and therefore improve its drainage. Tap-rooted plants can get deep enough so that their roots don't rot and they break up the texture of clay on their way down. In addition to them, rugged native prairie plants have the constitution to hold up in clay.
It can be a bit more effort to get plants established in clay soil than in loamy soil, not to mention the effort it takes just to dig a hole in clay.
However, the good news is that clay tends to be much higher in nutrients than a sandy soil.
Plants Recommended for Growing in Clay Soil
You will still need to meet other growing requirements, like sun exposure and USDA Hardiness Zones, but the plants listed here are all capable of not just growing in clay soil, but also thriving.
- Amsonia Blue Star (Zones 5-9)
- Asclepias tuberosa Butterfly Weed (Zones 4-9)
- Aster (various) Aster (Zones 4-8)
- Coreopsis Tickseed (Zones 4-8)
- Echinacea purpurea Coneflower (Zones 3-9)
- Eryngium yuccifolium Sea Holly (Zones 5-10)
- Helianthus angustifolius Swamp Sunflower (Zones 6-9)
- Helianthus x laetiflorus False Sunflower (Zones 5-9)
- Heliopsis helianthoides Ox Eye (Zones 4-9)
- Hemerocallis Daylily (Zones 3-10)
- Liatris pycnostachya Kansas Gayfeather (Zones 4-9)
- Liatris spicata Blazing Star, Gayfeather (Zones 4-9)
- Monarda fistulosa Wild Bee Balm (Zones 3-9)
- Ratibida pinnata Drooping Coneflower (Zones 3-10)
- Rudbeckia hirta Black-eyed Susan, Gloriosa Daisy (Zones 3-7)
- Sedum 'Autumn Joy' (Zones 3-10)
- Silphium integrifolium Prairie Dock (Zones 4-7)
- Silphium laciniatum Compass Plant (Zones 5-9)
- Silphium perfoliatum Cup Plant (Zones 5-9)
- Solidago Goldenrod (zones 5-9)
- Vernonia noveboracensis Ironweed (Zones 5-9)
- Yucca filamentosa Adam's Needle (Zones 5-10)
Ornamental Grasses Suited for Clay Soils
- Acorus gramiineus Grassy-leaved Sweet Flag (Zones 10-11)
- Andropogon gerardi Big Bluestem (Zones 2-7)
- Elymus canadensis Canadian Wild Rye (Zones 3-8)
- Miscanthus sinensis Eulalia Grass (Zones 4-9)
- Panicum virgatum Switch Grass (Zones 5-9)
- Pennisetum (various) Fountain Grass (Zones 6-9)
- Sorghastrum nutans Indian Grass, Wood Grass (Zones 5-8)
- Spartina pectinata Prairie Cord Grass (Zones 4-7)