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Centaurea cyanus
Growing calendar
Typical timing for central Japan (Kanto region). Shift it for your own climate, and record your actual dates.
Guides
- How to Sow Cornflower Seed: Autumn Versus Spring Sowing
- Cornflower Care: Support, Feeding and Keeping Plants Upright
- Keeping Cornflower Flowering: Deadheading, Cutting and a Longer Season
- Cornflower Growing Calendar: What to Do Each Season
- Cornflower Problems: Mildew, Aphids and Plants That Fall Over
Common problems
Start from what you can see on the plant.
Pests and diseases (7)
Problems recorded for this plant, most serious first.
Late Blight
Disease
Dark green water-soaked lesions appear on the leaves and expand quickly into brown dead tissue. White mold forms on the underside and at the lesion edge, and dark brown lesions spread to stems and fruit.
Sclerotinia Rot
Disease
The crown, stem or head rots in a water-soaked way and is covered in white cottony mycelium. Black sclerotia later form inside and on the surface, and the plant wilts and dies.
Southern Blight
Disease
The stem rots at soil level and white silky mycelium spreads over the crown and the surrounding soil surface. Brown sclerotia the size of rapeseed then form and the plant wilts and dies rapidly.
Root-knot Nematode
Pest
The plant wilts in the daytime and does not recover with feeding or watering. Pull it up and the roots carry beaded chains of galls of varying size with few fine roots.
Downy Mildew
Disease
Pale yellow to yellow-brown angular lesions form on the upper leaf surface with a gray-purple mold in the matching spot underneath. Lesions merge, the leaves die back and the plant declines early.
