University of Illinois Extension

Give Your Garden the "Blues"

What is it about the color blue that drives gardeners into a state of euphoria? That magical elusive flower color is one that is sought out and also almost held to a different standard, said Greg Stack, U of I Extension horticulturist.

“If you look at the color blue from a psychological standpoint, blue brings to mind a feeling of calm and serene moments,” said Stack. “It is thought of as a peaceful, relaxing color and when used in the garden, gives the garden the perception of added depth.”

Blue is also one of the least common colors found in flowers. Or is it? If you’re looking for that true blue rose or daylily, it’s going to be a while, if ever, before any of those show up. But if you want to include blue flowers in your garden now, there are plenty to choose from.

While many flowers are described as “blue,” they often are really some shade of purpleviolet or red-blue or magenta. And there are plenty of people who will debate long and hard that the “blue” that is there is not really blue. But that, as one would say, is in the eye of the beholder. So, when you are on your quest to gather up some “true blue” flowers for you garden, know that there are really a number of good choices to pick from.

“With annuals we can start with ageratum," he said.

‘High Tide Blue’ and ‘Blue Hawaii’ are two that will grow to eight to 12 inches tall and are great for full sun. They also draw butterflies. Another excellent dependable annual to put on your list is angelonia. ‘Angie Blue’, ‘Angelface Blue’ and ‘Archangel Blue’ will provide snapdragon-like flowers in blue shades continuously all summer. Growing to 12-18 inches tall they prefer full sun.

For something different try Evolvulus ‘Blue Daze.’ These low growing plants are good for full sun and offer contrasting gray-green foliage.

For something tall as well as providing 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 all are two to three feet tall, prefer full sun and provide season-long color with long spikes of blue flowers.

And then there are petunias for full sun gardens and containers. There are quite a few good blue petunias available such as ‘Blue Wave’, ‘Ultra Sky Blue’ and ‘Fantasy Blue’ to name just a few.

“And one thing to note about blue petunias. If you want fragrance, the color blue in a petunia will give it to you,” Stack said. “All 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 six to eight 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 six to 12 inches tall.

Perennials can also add to the blues in the garden. For early color look to Alpine Columbine. These will grow to 12-18 inches tall and bloom 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. These are often seen along roadsides in September and October with their blue flowers and yellow centers. For the garden look for ‘Blue Autumn’, ‘October Skies’, Smooth Blue Aster, New York Aster and ‘Professor Kippenburg #2.’ Most grow two to three feet tall and 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 attractive silver and variegated foliage. They do well in partial shade.

A compact, shrub-like perennial that gives some late season color and attractive gray foliage is caryopteris. ‘Dark Knight’ and ‘Blue Myth’ grow two to three feet tall, good for the sun and will attract both butterflies and hummingbirds.

Delphiniums without a doubt are one of the majestic, stately plants in the garden. ‘Belladonna’ provides multiple spikes of true blue flowers and grows to three feet tall. A shorter cultivar is ‘Blue Butterflies’ growing to 12-18 inches tall.

If you want to add what many would call a shocking plant to the garden include eryngium or sea holly. The flowers are spikey iridescent blue and are truly unique. Look for ‘Big Blue’. Growing to two to three feet tall, they flower well into autumn.

There are also a number of perennial geraniums to consider for their low growth habit and long bloom period. ‘Rozanne’ and ‘Brookside’ are two of the standards that will not disappoint.

Iris 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 and one of the fun plants 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 18-24 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 of 12-18 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.”