Coreopsis verticillata is a native plant of the Americas and belongs to the Asteraceae (aster/daisy) family. The word coreopsis is derived from the Greek "koris" meaning bug and "opsis" meaning appearance, and refers to the shape of the seed. It is an airy, mounding perennial with delicate fern-like leaves and masses of yellow, star-shaped 1-2 inch diameter summer-blooming flowers.
Coreopsis is an extremely tolerant plant, putting up with poor soil, dry conditions, and even neglect. It is deer resistant. It prefers full sun but will tolerate part shade. Over the years, the part of the garden where I planted coreopsis has become more heavily shaded, and the plants produce fewer blooms in full shade.
The only pest I have noticed on this plant is the occasional spittlebug. Spittlebugs suck at the sap in the stem of the plant. You can identify a spittlebug by the appearance of bubbly foam (looks like spit) on the plant. The foam protects the spittlebug from predators because they are hidden in the middle of it. Sometimes I have ignored the spittlebugs because the amount of damage they do is minimal. However, if they seem to be getting out of hand, I will use gloves and pluck them off the plants and dispose of them.
(no damage to coreopsis from grasshoppers in my experience)
Deadheading is recommended in order to encourage continuous blooms, but this can be difficult as the fresh blooms and those needing to be deadheaded are all mixed together. I don't usually bother with it, although later in the summer I may shear off the entire tops of the plants.
You can dig it up in the fall and separate the roots to spread the plant to other parts of the garden. I admit to having successfully spread this plant by simply cutting and digging a portion of it away using a spade.
I thought at one time that I would add the pink coreopsis to my garden too, since I was so pleased with the yellow. I was told that by the local garden center that the pink version doesn't bloom as well and is on a much earlier schedule than the yellow, so I dropped that idea. When I visited my sister later, I found out that she had the same idea, had followed through on it and wasn't pleased with the results.
Threadleaf Coreopsis is easy to grow, provides cheerful color that complements many other flowers, makes a good cut flower, and attracts butterflies! I highly recommend it as an easy-to-grow perennial to include it in your own garden!
Great Spangled Fritillary on Threadleaf Coreopsis