URBANA -- What is it about the color blue that drives gardeners into a state of euphoria? That magical, elusive flower color is sought out and almost held to a different standard, said a University of Illinois Extension horticulture educator.
“If you look at the color blue from a psychological standpoint, it brings to mind calm and serene moments,” said Greg Stack. “It is thought of as a peaceful, relaxing color and when used in the garden, gives the garden the appearance of added depth.”
Blue is also one of the least common colors found in flowers. Or is it? If you’re looking for a true blue rose or daylily, it will be a long time, if ever, before you find one. While many flowers are described as “blue,” they often are some shade of purple-violet, red-blue, or magenta. There are plenty of people who will debate long and hard that they are not really blue, but that is in the eye of the beholder. If you want to include blue flowers in the garden now, there are plenty to choose from.
“With annuals, we can start with Ageratum,” Stack said.
“High Tide Blue” and “Blue Hawaii” are two that will grow to 8 to 12 inches tall and do well in full sun. They also draw butterflies. Another excellent, dependable annual is Angelonia. “Angie Blue,” “Angelface Blue,” and “Archangel Blue” will provide snapdragon-like flowers in blue shades continuously all summer. Growing to 12 to 18 inches tall, they prefer full sun.
For something different, try Evolvulus “Blue Daze.” These low-growing plants are good for full sun areas and offer contrasting gray green foliage.
For something tall that provides good cut-flower material, look to Salvias. There are several good choices here: “Mystic Spires Blue,” “Rhea Violet,” “Sally Fun,” “Blue Emotion,” “Black and Blue,” and “Oceana Blue.” Most are 2 to 3 feet tall, prefer full sun, and provide season-long color with long spikes of blue flowers.
And then there is that garden staple for full-sun gardens and containers, petunias. There are quite a few good blue petunias available, such as “Blue Wave,” “Ultra Sky Blue,” and “Fantasy Blue,” to name just a few.
“One thing to note about blue petunias -- if you want fragrance, they will give it to you,” Stack said. “Petunias of other colors have little to no fragrance in comparison to the blue varieties.”
For partial shade, Lobelia “Rivera Blue Eyes,” “Lucia Dark Blue,” and “Techno Heat Dark Blue” provide 6- to 8-inch plants covered with tiny blue flowers. Scaevola is another blue annual that does well in part shade. The cultivars “Blue Fan” and “Bombay Dark Blue” can help add blue to shady areas. These annuals produce fan-shaped flowers and grow to 6 to 12 inches tall.
Perennials can also add to the blues in the garden. For early color, look to Alpine Columbine. It will grow to 12 to 18 inches tall and bloom from late spring to early summer. It is an heirloom variety that will also reseed easily. For-late summer bloom, there is a whole assortment of perennial asters, with their blue flowers and yellow centers. These are often seen along roadsides in September and October. For the garden, look for “Blue Autumn,” “October Skies,” smooth blue aster, New York aster and “Professor Kippenburg #2.” Most grow to 2 to 3 feet tall, and they are great butterfly plants.
If forget-me-not–like flowers are your preference, add some Brunnera to the garden. “Jack Frost” and “Variegata” are two cultivars that not only provide a cloud of tiny blue flowers but also have attractive silver and variegated foliage. They do well in partial shade.
A compact, shrub-like perennial that gives some late-season color and has attractive gray foliage is Caryopteris. “Dark Knight” and “Blue Myth” grow to 2 to 3 feet tall, do well in sun, and will attract both butterflies and hummingbirds.
Delphinium is without a doubt one of the majestic, stately plants in the garden. “Belladonna” provides multiple spikes of true-blue flowers and grows to 3 feet tall. “Blue Butterflies” is a shorter cultivar, growing to 12 to 18 inches tall.
To add what many would call a startling plant to the garden, include Eryngium, or sea holly. The flowers are spiky, iridescent blue and are truly unique. Look for “Big Blue.” Growing to 2 to 3 feet tall, it flowers well into autumn.
There are also a number of perennial geraniums to consider for their low growth and long bloom period. “Rozanne” and “Brookside” are two of the standards that will not disappoint.
Irises are classic members of the garden “blue group.” When it comes to early- and mid-season blue blooms, look for “Breakers” and “World Premier” in the bearded iris class and “Gerald Darly,” a tall, late-blooming blue flag iris.
And what is a garden without a little fun? A fun plant to include is Platycodon, or balloon flower. The puffy buds look like balloons and then open to star-shaped flowers. “Hakone Blue” and “Mariese” are good choices, growing to 18 to 24 inches and preferring a partial-shade site.
To round out the list of blue flowers, consider Veronica, a reliable summer bloomer for full sun. Compact cultivars, ranging in height from 12 to 18 inches include “Blue Bomb,” “High Five,” “Georgia Blue,” and “Royal Candles.” They are all good for cutting and, if you do, they tend to re-bloom later in the season.
“There are many more blue flowers to consider in the area of vines and also bulbs,” said Stack. “Never was there so much ‘blue’ to make you feel good.”