Perennials for Clay Soil
The problem with clay is that it holds moisture and this tends to rot out the roots of all but the toughest of plants.
If you decide that you'd like to amend your clay soil, here's how you can do it.
Perennials for Clay Soil
Acanthus will accommodate itself to the heavier soils although it doesn’t make them any hardier in the wintertime (if you can’t grow them in regular soil, you can’t grow them in clay).
Achillea will grow anywhere.
Aconitum or monkshood is a classic lover of heavier soils.
Alcea or Hollyhocks surprisingly grow well on clay soils.
Amsonia should do well on clay.
Anchusa is good once established and protected from slugs (slugs like damper soils and they love anchusa).
Anemone are excellent perennials for clay soils and will thrive and flower well on clay. The taller varieties are excellent.
Asters will grow anywhere. Clay or concrete does not matter to this plant.
Bergenia should be fine.
Brunnera macrophylla should do well although I’m not sure about the newer hybrids – you’ll have to trial them.
Campanula the taller species do better than shorter, so do C persificolia. You’ll find variations between varieties. ‘Loddon’s Pink apparently does well but “Telham Beauty’ is variable.
Chrysanthemum (Shasta Daisies) do well enough although they will be shorter-lived on clay than in well drained soils.
Coreopsis verticillata is the best in clay. Forget all others.
Doronicum spring bloomer, one of the earliest of yellow daisies.
Digitalis or foxglove – scatter the seed and let nature take its course.
Echinops make good clay soil plants. These things will grow anywhere but in a closet.
Geranium: most of the geraniums will tolerate clay soils.
Helenium are very showy daisies and they will grow handsomely on clay soils.
Helianthemum or perennial sunflowers will grow nicely (if it can be said that this plant ever grows “nicely”) :-)
Heliopsis is another of the perennial sunflowers and it too grows well.
Hellebore surprisingly enough are listed as surviving quite nicely.
Hemerocallis are great on clay. They do take a little longer to become established but can’t be killed. Heuchera are great perennials for clay soils and this is a relief given the amount of semi-shaded clay around
Iris germanica or flag iris will grow on heavier ground although many of the species iris will not
Kniphofia will tolerate clay.
Lysimachia will tolerate heavy soils as well but given the fact that you can grow this plant in asphalt and not kill it, this does not surprise me.
Lythrum will do quite nicely
Monarda or beebalm survive and thrive on the regular moisture of clay.
Rudbeckia believe it or not, the biennial forms will live on clay as will the taller species such as ‘Herbstonne’ and even the most popular ‘Goldsturm’ will be fine.
Salvia nemerosa is reputed to do well on these soils but other salvia are very short-lived and are to be considered as annuals.
Senecio are long-lived but then again, I’ve never been a major fan of this plant.
Solidago will live quite comfortably and this is a good thing.
Thalictrum is a good plant and will do well.
Verbascums will tolerate clay but I note that they are short lived at the best of times. I haven’t seen reports of the newer hybrids and their performance. I’ve only grown the newer hybrids (and they rival Delphiniums in colour now) on well-drained soils.
If you have other perennials for clay soils that do well in your garden, please let me know and I'll add it to this list.
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