I bought 18 beautiful coreopsis plants (all in bloom) brought them home and planted them. I was told to keep them watered until they were established. It appears that the buds are turning black before they bloom. Too much water??? I deadhead every day. Please help.
Check the soil; it should be moist, never soggy or dry.
Make sure the soil and the container have a drainage hole and that the excess water is draining.
You may need to water daily, and even twice a day if the temperatures are above 85 degrees F.