How to Grow Cornflower from Seeds

Cornflower seeds are easy and inexpensive to grow in the home garden. Although they are best known for their cornflower blue colored blooms, these annuals also come in shades of pink, white, red, lavender and maroon. Another variety is Centaurea Americana, or bachelor’s button. Ranging in height from 10 inches to 2-1/2 feet, cornflowers produce single or double flowers with fringed petals. Leaves are often gray-green in color. Dwarf varieties are suitable for edging and borders, while taller Centaureas are popular in cottage gardens. Easy to grow from cornflower seeds, cornflowers can be started indoors or sown directly outdoors. Since taller varieties may not be readily available at local nurseries, planting cornflower seeds is the only way to get them in the garden.

Step 1: Planting Cornflower Seeds Outdoors

In areas with mild winters, annual cornflower seeds can be sown outdoors in September. They will begin to grow that season and will bloom in the spring. For colder climates, plan on sowing cornflower seeds in spring as soon as weather permits.

Several successive plantings of cornflower seeds will result in near-continual production of blooms throughout the growing season. This is because annual cornflowers are not long-lived plants. Garden experts recommend a second planting in spring if cornflower seeds are first sown in fall.

• Sow seeds in a good, slightly alkaline garden soil to a depth of ½-inch.
• Water well and keep moist until germination.
• Cornflower seeds will germinate in roughly 7 to 10 days (annuals) and 2 to 3-1/2 weeks for perennial varieties.
• For annuals, keep the plants crowded. For perennials, thin them out so they're spaced 2 to 3 feet apart.

Step 2: Indoor Planting of Cornflower Seeds

Check the calendar and plant cornflower seeds indoors about one month before the last frost – or before planning to set them outdoors.

• Use a growing medium and fill growing containers or peat pots.
• Moisten mixture and allow it to drain.
• Sow 3 to 4 cornflower seeds per pot and cover with ½-inch of growing medium. Mist lightly with water.
• Cover containers with plastic bags or sheeting and place in a warm location to allow seeds to germinate.
• After seed germination, remove plastic and place containers under grow lights or in a sunny location.
• Once seedlings reach about 2 inches tall – and have one pair of true leaves – choose the strongest seedling to keep and pinch off the others at soil level.
• Use a water soluble fertilizer once.
• Transplant seedlings outdoors when they are 4 inches tall (or less).

Cornflower seeds are easy to sow, both indoors and outdoors. Watch the calendar and plant accordingly. These prolific flowers, while short-lived, add interest to almost any garden.