Cornflower

Value to bees

Nectar

High

Pollen

Moderate

As a honey crop

Feeds the colony but rarely yields a surplus

Which bees, and why

Worked by honey bees, bumblebees and solitary bees, with ants and wasps at the extrafloral glands beneath. Watching the two feeding sites simultaneously is the easiest demonstration of extrafloral nectar available in a garden.

Florets are tubular but short, and the extrafloral nectaries are entirely exposed — so it serves both the short-tongued and long-tongued ends at once.

Worth knowing

Good nectar over a long season from a cheap annual, and one of very few garden plants where a reader can actually see extrafloral nectaries at work.

Flowering

In flower

June to September (northern hemisphere)

Long if deadheaded, and autumn-sown plants flower several weeks earlier than spring-sown ones.

When nectar flows

Generous nectar within the floret, plus extrafloral nectaries on the bracts that secrete throughout the plant's life. The extrafloral glands evolved to recruit ants as bodyguards, and bees exploit them opportunistically.

Year-to-year variation

Reliable from seed each year. Not a honey crop.

Growing it

Conditions

Full sun and poor, well-drained soil. It flops badly on rich ground.

Size

40-90 cm.

Native range

Probably the eastern Mediterranean, spread across Europe as an arable weed with cereal cultivation over millennia.

Suits

Meadow or wildflower area, Small gardens, Large gardens, Containers and window boxes, Farm scale

• Sow direct in autumn for the earliest and strongest plants, or in spring for a later display.
• A standard component of arable-margin and wildflower seed mixes, and one of the more reliable species to establish.
• Deadhead to prolong flowering, then let the last flush seed so it returns.

What it looks like

A slender grey-green annual with narrow leaves and intense blue flower heads, the outer florets flared and ragged around a smaller purple centre.