Bachelor's button (Centaurea cyanus) is a commonly cultivated ornamental that originated in southern Europe. It is sometimes included in wildflower seed mixes and it often escapes from cultivation. Cultivars include a range of flower colors from white and pink, to blue-purple.

Growing Tips

Soil: Cornflowers are very adaptable and will grow in the poorest of soils. Ideally they prefer a neutral to slightly alkaline soil pH.

Planting: These are cool weather flowers, meant to go in the garden at the start of the season. If you'd like to get a head start, you can start seed indoors 6 - 8 weeks before your last frost date. Seed also does well when direct sown right around the last spring frost date. Plants that are allowed to go to seed will probably self-sow.

Maintenance: Minimal watering and no fertilizer is needed to keep these annuals going. Established plants can tolerant dry soil, but regular water will keep the plants healthier.

The plants can become floppy and can be flattened by rain or wind. You could stake them while young or simply plant them near taller plants that will support the stems, as they grow.

You can deadhead, to prevent self-seeding, but many birds will eat the seeds.

Suggested Varieties

Very often you will find seed that is simply labeled cornflower, cornflower mix or sometimes labeled by color. There are named varieties out there, but as new ones are introduced, older varieties can disappear. It's very easy to save your own seed though, if you should find a variety you truly love.

• Centaurea cyanus 'Blue Boy': Probably the most popular variety, with double flowers in "cornflower blue".
• Centaurea cyanus 'Black Magic': There are several dark purple flowered varieties, with 'Black' in their names.
• Centaurea cyanus 'Dwarf Blue Midget': bright, blue flowers on 6 - 12 in. plants. The dwarf varieties are nice for rock gardens and the front of a border or along edges.

Centaurea montana is a perennial cornflower that is hardy in USDA zones 3 - 8. It blooms in late spring.

Pests & Problems

Since cornflowers are grown as annuals, they don't usually have the time to develop serious problems. However they can occasionally be prone to powdery mildew, wilt, rust and rots and are attractive to aphids and mealybugs.

More info here:

https://gobotany.newenglandwild.org/species/centaurea/cyanus/

Hope this helps.

Courtesy of the NYBG Plant Information Service.  For other plant tips check out our libguides here.