Cheerful, bright yellow fringed blooms floating over deep green foliage certainly help "Early Sunrise" coreopsis (Coreopsis grandiflora "Early Sunrise") live up to its name. This cultivar and other coreopsis varieties thrive in full sun and average to poor garden soil in U.S. Department of Agriculture plant hardiness zones 4 to 9. Most coreopsis species and cultivars are yellow, some with red-brown spots at the base of the petals. Varieties may have single, double or cone-shape petals. "Early Sunrise" has 2-inch flowers with a double layer of fringed petals on dark yellow to orange centers on 12- to 18-inch stems. Relatively trouble-free perennials, there are a few problems to troubleshoot when your "Early Sunrise" doesn't perform.
Rich, fertile soil and moist conditions are ideal for most perennial and annual plants, but not so for "Early Sunrise" and other coreopsis. Coreopsis plants prefer dry, poor soil and tend to sprawl -- flop over and open up at the center -- when given too much of a good thing. Cut "Early Sunrise" back to within a few inches of the ground in late summer to spur the growth of new, compact foliage. Consider moving the plant to a drier site with less rich soil in the fall or early spring.
"Early Sunrise" can bloom from spring through fall with proper care. The plant produces a first, profuse flush of bloom in mid-spring -- "Early Sunrise" flowers earlier than other varieties -- followed by regular, but less profuse bloom. Cut the stems down to the basal or base foliage after blooms fade to increase flower production. Coreopsis and "Early Sunrise" in particular needs plenty of sun to flower. Michigan State University tests published in the July 2005 issue of "Greenhouse Product News" found that the cultivar flowers best with a full 14 hours of sunlight. The plant can be moved to a sunnier location in late fall or early spring.
Though they are perennials, coreopsis have a reputation for early die-back when the plants become overcrowded and may only live for three to four years. Dig up and divide the clump-forming plant in late fall or early spring to give the plant a new lease on life. Allow 12 to 15 inches between divisions when replanting. Plants that sit in wet soil over a rainy winter may also not come back in the spring.
Crown Rot and Powdery Mildew
Coreopsis grown in too-moist conditions can suffer from crown rot. Plants affected by crown rot may actually look like they need more water, with wilted, brown foliage. It also develops small white fungal growths and webs. Remove and discard these plants. Plant coreopsis crowns slightly higher than soil level and keep any mulch from around the base of the plant to prevent the fungus from developing. Powdery mildew -- a dusting of white fuzz on the upper surfaces of leaves -- can also be an issue with coreopsis, though mainly cosmetic. Improve air circulation by increasing spacing between plants or apply copper sulfate at first sign of the diseases.
Insects are not a big problem for coreopsis, but they can be affected by aphids. Aphids suck fluid from the leaves, stealing nutrients and giving leaves a distorted, puckered appearance. Their secretions can also lead to the development of sooty mold, which can decrease photosynthesis. Knock off aphids with a strong stream of water early in the day to allow the water to evaporate in the sun.
- Missouri Botanical Garden: Coreopsis Grandiflora "Early Sunrise"
- University of California Marin County Master Gardeners: Coreopsis Grandiflora "Early Sunrise"
- University of Florida Extension: Coreopsis spp., Tick-seed, Coreopsis
- Greenhouse Products News: Coreopsis: A Great All-American Genus
- Orlando Sentinel: Gardeners Smile on Easy, Showy, Sunrise Coreopsis
- University of Illinois Extension: HortAnswers: Tickseed Coreopsis
- Penn State Extension: Coreopsis Diseases
- University of California Integrated Pest Management Program: Aphids