Answers to questions:
No, I am not deadheading at all. I wait til the Spring, then just break off all the stems a few inches above ground. I get lots of birds feeding on the flower seeds, and hopefully dropping the seeds along the fenceline. By doing nothing myself, the echis have spread nicely along the fenceline, from bird droppings I assume. But existing clumps are shrinking every year.
Groundhogs. Hmmm. I did see a groundhog outside my fence a few weeks ago.
Native vs storebought. Don't know. I think we bought them as small plants 30 years ago. I have tried planting seeds, and sometimes they actually come up, but usually nothing happens. Have tried planting seed pods from the actual plants, and they sometimes come up.
I think they must be propagating in some spots, too.
Hot lately. I have been watering them every day. Usually I never have to water them, but some of the flowers are falling off, I assume due to all the heat and no rain.