Q.Why Are The Coreopsis Dying?
I planted Jethro Tull coreopsis about a month ago. They are starting to brown and die, starting with the innermost leaves. What am I doing wrong? I have been watering every 3 days using drip irrigation (1 gph for 1 hour).

Certified GKH Gardening Expert
This looks like a bacterial infection, likely, from a little too much water.
Rather than watering on schedule, make sure to water when the soil dries out down to about 3 inches, thoroughly. I would even say to let them go even longer than that, though. They are a drought tolerant wildflower, and they will not tolerate overwatering. \
These articles will help:
https://www.gardeningknowhow.com/ornamental/flowers/coreopsis/growing-coreopsis-flowers.htm
https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/testing-moisture-in-plants.htm