Heavy and clay soils can appear to be very resilient to drought and high temperatures and they certainly hold moisture better than sand and chalk. However, the danger is that once they dry out, the top layer of the ground bakes hard and then water can’t penetrate it, effectively baking the plants trapped within. Following which weeds do best in your soil can be the easiest way to gauge the type of plants that will cope, and on heavy cold clay soil in southern Scotland the clear winner has always been DOCKS! Perennial plants with big leaves to shade out more delicate plants and a huge taproot, they easily dominate given the chance.
Now although dock flowers can bring a rusty textured beauty to arrangements, I’m not suggested all those on clay soil actually plant them, just think about their characteristics and look for similar plants. Inula is certainly one that can outcompete the humble dock. It has huge leaves, sturdy stems and flowers that held their own on the hottest day yet recorded in Scotland (34.1C at Charterhall, a few miles from here). It’s definitely not a small plant but it churns out glorious big flowers over a long period, they can be used singly in bouquets, in clusters in arrangements, as big buttons once the petals have died and the dry seedheads look like soft gold mushrooms. The long taproot gives it access to deeper moisture even in drought conditions and it’s reliably perennial even down to -20C. We have 2 varieties that flower in succession - Inula hookeri with clusters of big golden daisies that mature to a rich brown and Inula magnifica which is taller, flowers a few weeks later and has slightly smaller daisy blooms. And they’re both perfectly yellow!
Paula
Mill Pond Flower Farm
Inula magnifica - gorgeous yellow daisies on long strong stems, brilliant for cut flowers
Inula hookeri - after the petals have gone, the flower heads are big brown buttons, brilliant for cutting and arrangements