Five plants come up again and again on lists of blue flowers from seed. Cornflower, borage, love-in-a-mist, forget-me-not and morning glory "Heavenly Blue" all grow from a packet sown in place. Each one has forms that read honest blue rather than violet. The list stays short for a reason. True blue turns up in less than 10% of flowering plant species, per Zhou and colleagues in Ornamental Plant Research. Seed racks have little to work with.
The morning glory "Heavenly Blue" on my own mailbox post opens a new set of flowers every morning. The saucers are wide sky blue with a pale throat, and by mid afternoon they have folded shut. Next morning brings a fresh batch. The vine keeps that up until the first frost takes it down.
These five share a habit rather than a promise. They are annuals and biennials sold for direct sowing, which is why garden writers and seed sellers group them as the easiest blue flowers to grow. That grouping comes from gardening sources, not from a side by side trial, so read it as a starting point. Four of them are blue annual flowers that sprout, bloom and finish in one season. Forget-me-not runs on a slower clock and often flowers in its second spring.
Sowing dates swing hard by region, so pull up your local extension calendar before you open a packet. The order of the work stays much the same wherever you garden.
Cornflower, borage and love-in-a-mist go straight into the bed where you want them. They are usually sown in place because they resent being moved.
Sow morning glory at the base of a fence, trellis or post once frost risk has passed for your area. The vine climbs fast and needs the support ready first.
Sow it once and leave the spent plants standing so the seed falls where it lands. Flowers follow in the next spring rather than the same year.
Ask your regional extension calendar for sowing windows instead of trusting the back of the packet, which is written for the whole country.
Year two is where these plants pay you back. Cornflower, borage and forget-me-not all get flagged as self-seeding blue flowers, and the Almanac notes that habit for its annual blues. Leave the seed heads standing and you may never buy a second packet. I pulled a dozen borage volunteers out of the path last spring and left the ones in the bed alone. Young seedlings let go with a light tug.
That same vigor is worth a check first. A plant that sows itself well in one state can carry an invasive or regulated listing in another. Look up your local rules before you scatter seed freely. It takes a minute and saves you a real headache later.
A packet labeled blue deserves the same doubt you give a nursery tag. Plenty of seed sold as blue opens violet or mauve. A named cultivar such as "Heavenly Blue" tells you far more than a generic blue label ever will.
Start with cornflower and love-in-a-mist if you want blue this summer without much fuss. Both take rough soil and both sow in place. They also drop enough seed to show up again on their own. Add borage nearby for the star shaped flowers and the bees that follow them.
Tuck forget-me-not into the same bed and the color carries into early spring, before the annuals wake up. Morning glory then covers the summer end of the season on a post or fence. Those four plantings give you blue from spring through frost with one afternoon of sowing and a habit of leaving seed heads alone.
Read the full article: 10 True Blue Flowers and Why Blue Is Rare
