Q.what is the best cultivar of coneflower to grow in the heavy clay soil in bellaire (Houston) texas?
I would like to plant them along a concrete fence. Most areas get full sun, some are under a tree.
The most consideration is to buy a native coneflower. These are the plants that have adapted to your area. The same plant from a different region will have slightly different characteristics. Here are two websites to help you out: https://npsot.org/wp/houston/go-native/
https://www.wildflower.org/plants/combo.php?fromsearch=true&distribution=&habit=habit_herb&duration=duration_perennial. This page is for East Texas. On the right, you can change the search terms if you wish. Several coneflowers are listed (Echinacea). Click on a plant for more information; near the bottom of the page it tells you where you can find this plant or seeds.