Clay soil is a challenge in the garden. After a heavy rain, water doesn’t percolate well, it stays wet and it can cause plant roots to rot and soil to compact and become hard and crusty. Clay’s density makes it difficult for new plants to get established, too, as young roots have trouble growing through it. Over time, this makes the plant more susceptible to rot and disease.
While all clay soil has the same basic properties, different types have specific qualities. In the Southeast, for example, clays (like that red Georgia clay above) tend to be low in nutrients and benefit more from regular fertilizing than other areas. (A thorough soil test will tell you the best type of fertilizer and how much to use to ensure your clay offers your plants all the nutrients they need to thrive.)
In the West and Southwest, clay can combine with calcium to form caliche, a concrete-like layer. This makes it difficult for plant roots to grow and water to move through. It has a high pH, and that can cause plants to suffer micronutrient deficiencies. (The best way to handle caliche is to remove it. If that’s not feasible, break it up with a pickaxe so water has an easier time reaching plant roots.)
One important step to growing a garden in clay soil is to amend with organic matter, such as compost or manure. The other is to choose clay-compatible plants that can tolerate the clay soil in your region. Heavy clay may not be your best friend, but with some organic matter, the right plants and a little patience, it doesn’t have to ruin your garden. Read on to find out more about plants that will grow in your clay soil!
Clay soil is slow to warm in spring, shrinking already short seasons.
False indigo (Baptisia australis)
Type Perennial Blooms North American native has blue flowers in late spring Light Full sun to part shade Size 3 to 4 ft. tall and wide Hardiness Cold-hardy in USDA zones 3 to 9, heat-tolerant in AHS zones 9 to 1
Lily of the valley (Convallaria majalis)
Type Perennial Blooms Fragrant, white flower spikes in spring Light Part to full shade Size 6 to 8 in. tall, spreading Hardiness Cold-hardy in USDA zones 2 to 7, heat-tolerant in AHS zones 7 to 1
Purple coneflower (Echinacea purpurea)
Type Perennial Blooms bees and butterflies love the pink or white summer flowers Size 24 to 48 in. tall, 18 to 24 in. wide Light Full sun to part shade Hardiness Cold-hardy in USDA zones 3 to 9, heat-tolerant in AHS zones 9 to 1
Heavy clay may leave standing water for days after summer thunderstorms.
Canna (Canna spp. and hybrids)
Type Rhizome Blooms Big, bold leaves and dramatic red, orange, pink, yellow or white summer flowers Light Full sun Size 18 to 96 in. tall, 12 to 48 in. wide Hardiness Cold-hardy in USDA zones 7 to 11, heat-tolerant in AHS zones 12 to 1
Daylily (Hemerocallis spp. and hybrids)
Type Perennial Blooms Flowers of almost any color bloom in summer; thrives in practically any soil Light Full sun to part shade Size 12 to 72 in. tall, 9 to 40 in. wide Hardiness Cold-hardy in USDA zones 3 to 11, heat-tolerant in AHS zones 12 to 1
Hardy hibiscus (Hibiscus moscheutos)
Type Perennial Blooms Large red, pink or white blooms in summer Light Full sun to part shade Size 2 to 5 ft. tall, 2 to 6 ft. wide Hardiness Cold-hardy in USDA zones 4 to 9, heat-tolerant in AHS zones 9 to 1
High-pH clay soils in this region often leave plants starving for iron.
Russian sage (Perovskia atriplicifolia)
Type Woody perennial Blooms Pollinators love the silvery foliage and violet flowers in mid- to late summer Light Full sun Size 2 to 5 ft. tall, 2 to 4 ft. wide Hardiness Cold-hardy in USDA zones 5 to 9, heat-tolerant in AHS zones 9 to 1
Lead plant (Amorpha canescens)
Type Shrub Blooms Blue-purple flowers in summer Soil?? Foots add nitrogen to the soil Light Full sun Size 24 to 36 in. tall, 24 to 30 in. wide Hardiness Cold-hardy in USDA zones 2 to 9, heat-tolerant in AHS zones 9 to 1
Yarrow (Achillea millefolium)
Type Perennial Blooms Golden-yellow flowers in summer Light Full sun Size 6 to 60 in. tall, 8 to 36 in. wide Hardiness Cold-hardy in USDA zones 3 to 10, heat-tolerant in AHS zones 10 to 1