Cornflower

Centaurea cyanus

Asteraceae

The true-blue field flower of old grain — edible petals, a cut stem, and an insectary that does not mind poor soil.

Annual bachelor’s button. Petals are a traditional garnish and tea color. Not knapweed weeds of other Centaurea species.

Parts used: Petal · Flower head
Traditional notes: Edible petal · Tea color · Cut flower · Insectary
Grow · USDA 6b: Hardy annual. Sow cold. Direct in early spring, or late fall. Thin. Succession for a longer blue. In work: Mar · Apr · May · Jun · Jul
Harvest: Cut when the outer florets are just open. Petals anytime.

A row with alyssum and dill is a hoverfly strip.
Lean ground. Compost makes a floppy, pale plant.

Safety

Unsprayed garden flowers only

Companions

Plant with Anise hyssop, Bee balm, Borage, Cabbage, Calendula, Clove pink.

Lore

Cyanus is the blue. It was a Prussian emblem and a weed of wheat. Cleaner agriculture made it rare in fields and common in seed packets — the usual modern path for a once-ordinary flower.

The Herbarium — a teaching catalog, not a clinic. Traditional use is history, not a prescription. USDA 6b dates are a week either way, not a promise. Do not eat, drink, or harvest a plant you cannot name.