Centaurea cyanus
flowerThe classic annual wildflower of European grain fields — intense blue button flowers on wiry 18 to 24-inch stems. Edible petals are used as a garnish and food coloring. Extremely cold-hardy and one of the few flowers that can be direct-sown in fall for the earliest spring bloom. A valuable bee plant and one of the simplest flowers to grow from seed.
Sun
full sun
Water
Every 3 days
Bloom
~65 days
Difficulty
easy
Lifecycle
annual
One season, then done
Spacing
9-12 in
Planting Depth
1/4 in
Soil pH
5.5-7.5
Soil Type
Average, well-draining
Hardiness Zones
Zones 2 – 11
Grown as an annual — this range is its winter hardiness, but you can grow it for a single season in any zone.
When to Fertilize
Minimal; too much fertility produces large plants with fewer blooms
Fertilizer
None or very light balanced fertilizer; lean soil preferred
Direct sow in early spring 4 to 6 weeks before last frost, or in fall for overwintered plants that bloom earlier than spring sowings. Cornflowers prefer cool weather and actually bloom less well in summer heat. Succession sow every 3 to 4 weeks for continuous blooms. Deadhead spent flowers to prolong bloom. Self-seeds freely and will naturalize in open areas of the garden.
🌼 Have a different variety?Cultivars of the same species usually share the same basic care — they differ mainly in flower color, height, and bloom form, not in how you grow them. So this guide still applies even if your exact variety isn't the one shown.
Direct sow
Mar 18
Projected first bloom
May 22
Good neighbors that attract beneficial insects or deter pests
Proactive ways to stop trouble before it starts — tap a name with an arrow for its full guide
Water blast; insecticidal soap; cornflowers rarely have severe aphid problems
Space well for airflow; neem oil at first sign; most common late in the season
Remove infected plants immediately; control leafhopper vectors
Reflective mulch; spinosad spray; blue flowers tend to attract fewer thrips than yellow or white
Cut stems for arrangements when flowers are fully open and the center shows a tight button of petals. Vase life is 5 to 8 days. Recut stems under water. Edible petals are mildly sweet and slightly spicy — pull individual petals from the head for use as a garnish. Dry whole flowers for wreaths and potpourri by hanging upside down immediately after cutting.
As a companion plant: one of the most important early-season nectar sources for bumblebees and mason bees before summer flowers begin. Petals contain cyanins, the same blue anthocyanin pigments found in blueberries. Traditional herbal use of petal infusion as an eye wash and mild diuretic.
For educational and informational purposes only — HomeSown is not medical, health, or other professional advice. Always positively identify any plant before handling or eating it; some plants, and some parts of otherwise-edible plants, are toxic. Consult a qualified professional before consuming or otherwise using any plant, especially if you are pregnant, nursing, taking medication, or have a health condition.