Coreopsis leavenworthii is a Florida native annual or short-lived perennial and the official state wildflower of Florida. It produces bright yellow ray flowers with dark centers from late spring through fall and is well suited to open meadows, rain gardens, and naturalized plantings across the Gulf Coast region.
The plant self-seeds prolifically and can colonize open, disturbed, or seasonally flooded sites with little intervention. It tolerates prolonged wet conditions and brief dry spells once established, making it one of the most adaptable wildflowers for warm, humid climates. It is closely related to Coreopsis tinctoria and is sometimes grouped with it in older botanical references. Sandy or loamy soils with neutral to slightly acidic pH suit it well; rich, amended soils encourage lush foliage at the expense of blooms.
As a native Asteraceae, it provides consistent nectar and pollen through the growing season for native bees, skippers, and butterflies. Allowing plants to go to seed at the end of the season sustains naturalized stands without annual replanting.
Powdery mildew
White or grey powdery coating on leaves - usually starting on older growth in humid conditions or when nights cool.
Improve air circulation by thinning plants. Apply neem oil or potassium bicarbonate spray at first sign. Avoid overhead watering.
Fungal leaf spot
Brown or purplish spots on the leaves, often ringed with a yellow halo, that spread and merge in warm, humid, or wet weather; heavily spotted leaves yellow and drop early.
Pick off spotted leaves and clear fallen debris to remove overwintering spores. Improve air circulation by thinning, and water at the base so foliage dries quickly. If it persists, apply a copper- or sulfur-based fungicide at the first sign.
Aster Yellows
Deformed, greenish flowers, stunted growth, and yellowed foliage. Flower centers may produce tufts of leafy growth instead of normal petals.
No cure. Remove and destroy infected plants immediately to stop spread. Control leafhoppers, which transmit the disease, and remove nearby weed hosts.
Root rot
Plants wilt, yellow, and stunt even in moist soil; lower stems and roots turn brown, soft, and mushy and the plant may collapse. Most common in heavy, wet, or poorly drained ground.
Improve drainage and stop overwatering, and never plant too deep. Lift and destroy badly affected plants along with the soil around the roots. Grow in raised or free-draining beds to prevent it returning.