Clay tolerant herbaceous flowering plants for herbaceous borders & mixed planting

All the plants listed below will tolerate heavy clay soils whilst providing a show of summer blossom and then die back to the ground in the winter months. Some might simply classify these plants as border flowers, but seeing as they come back year on year (if you look after them) we prefer to call them herbaceous perennials.

There is a wide selection of flowering plants that will tolerate heavy clays; many will also tolerate light shade as well as a degree of water logging during the winter months. Clay will often dry out to form a hard impenetrable crust during the summer months, so don’t assume that moisture loving plants will put up with clay soils, as more often than not they won’t.

As with all other herbaceous plants you will need to put some time into maintenance; mulching around plants with well rotted compost - but not bark! Regular mulching will improve soil fertility over time, making the clay easier to dig and plant into and greatly improving the lot of your border plants. Mulch will also lock in soil moisture greatly reducing the risk of summer hardening and surface cracking, allowing establishing plant roots to penetrate deeper into un-compacted soil. A deep mulch can reduce weed growth, in fact you might say that mulch is an all round wonder treatment for the soil and plants alike, and I think I would go along with that statement.

Many of these clay tolerant herbaceous plants will also require lifting and dividing to encourage rejuvenated growth and flowering, alongside other regular maintenance tasks such as summer stacking to stop taller plants from collapsing and good winter bed tidy.
Of course you can always mix herbaceous perennials in with shrubs and ground cover – but even in clumps they will still require regular maintenance.