6 Best Blue Perennial Flowers (With Photos)

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By Arthur Mbanefo

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True blue flowers remain a rarity in nature. And most gardeners would kill to have them in their gardens. 

But since they are difficult to find, most of us don’t stand a chance. 

However, we have managed to scrap some blue perennial flowers that are easily accessible that you can use to make a rare splash of color in your garden. 

Unfortunately, genetic modification and breeding programs make most of them blue. But we still have some TRUELY blue flowers.

Top 6 Blue Perennial Flowers

Below is a short list of some of the most commonly planted blue perennial flowers by homeowners and gardeners alike: 

1. Hydrangea

With acidic soil with 5.5 or less pH, your Hydrangea can yield bright blue flowers that light your outdoor space. 

Their mophead and cluster flowers make them a highly sought-after choice for garden design, landscaping, floral arrangements, and wedding bouquets. 

Although they come in different species and cultivar that differs in blooming time, most will bloom from early summer to fall. 

Pruning and growing conditions also significantly affect how well they bloom.

So you have to do everything right, from providing well-drained soil to regular watering and protecting it from the scorching afternoon sun and giving the right dosage of fertilizer.

2. Salvia

You can not help but stare at this perennial shrublike herb with brilliant racemes and ovate, downy foliage. Plus, they smell incredibly nice, like most members of Lamiaceae (the mint family).

Sadly, there aren’t TRUE blue salvia but purple and violet that give that bluish effect. Salvia are recognized for their culinary and ornamental uses. 

Yes, many dishes benefit from their distinctive flavor. 

However, they are mostly valued for their ornamental presence –especially Salvia splendens, Salvia nemorosa, Salvia farinacea, and Salvia greggii.

They are commonly used in containers and garden borders and harvested as cut flowers. We can’t forget to mention their pollinating potential and their thriving Zones 7-10 grounds.

3. Rose Of Sharon

Rose of Sharon isn’t a member of the Rosaceae (the rose family). Instead, it belongs to the Malvaceae (the hibiscus, or mallow, family). 

So you would expect that hibiscus-like, large, trumpet-shaped flowers. 

The Rose of Sharon becomes pleasant to watch when more blooms hang on the stems from late summer to early fall. Their nectar-rich blooms draw bees and butterflies in. 

Among other things, they are interactive with neighboring plants when paired with the right ones. 

Some of their companion plants are Ornamental grasses like switchgrass or Karl Foerster feather reed grass, Daylilies, Coneflowers, Black-Eyed Susans, Russian Sage, Butterfly Bush, Lavender, and some Phlox. 

4. Cornflower

A flowering plant like the cornflower standing 30–90 cm (1–3 feet) tall with gorgeous, daisy-like blooms can greatly boost your garden’s curb appeal.

They also come in vibrant blue, purple, pink, and white ray florets. Most gardeners love to shuffle these different cornflower shades to create a striking combo.  

And since the cornflower is rich in nectar, pollinators will always lurk around your garden, which helps nearby fruit and vegetable crops. 

The invites cornflower sends to parasitic wasps, ladybugs, and other beneficial insect also helps reduce garden pest like caterpillars and aphid.

Aside from that, they are self-sower and drought-tolerant flowers, which is a plus for their survival.

Companion Plants for Cornflowers include Dill, Sunflowers, Marigolds, Zinnias, Nasturtiums, Alyssum, and Lavender.

They are also comfortable around herbs like oregano, basil, and parsley.

Planting them next to cucumbers and tomatoes will give you a bountiful yield since they attract pollinators. 

5. Dwarf Morning Glory

Dwarf Morning Glory is one of the highly regarded blue perennial flowers. And part of that is due to its versatility.

Its low-growing natural and vibrant true-blue blooms qualify it for hanging baskets, containers, rock gardens, and ground covers.

Many homeowners have also used it in their flower beds and borders. Propagation is from seeds, which you can easily get from the garden center. But the sowing time MUST be right. It should be after the last frost.

Since their flowers are nectar-rich, they attract pollinators such as Butterflies, moths, bees, birds, and hoverflies.

They also form good companion plants with Alyssum, Marigolds, Verbena, Zinnias, Portulaca, Petunias, Nasturtiums, Sunflowers, Salvia, Dianthus, Cosmos, and Cleome.

6. Iris

The Blue Suede Shoes bearded iris is a mid-sized iris standing 24 to 36 inches tall (60 to 90 centimeters) with a rich, deep royal blue bloom along the fine hairs on the lower petals.

They are gorgeous and mostly bloom in the spring but return during later summer.

However, the Bearded Iris needs at least 6 hours of daily sunlight, well-drained alkaline to neutral soil, and regular watering, particularly during their active growth period for optimal flowering.

Don’t worry; they aren’t as demanding as most perennials. But you will have to deadhead every once in a blue moon to promote further flowering.

And once winter hits the ground, the rhizomes MUST be protected from the freezing temperatures with the help of mulch layers.

Irises are highly selective with surrounding plants. But few companion plants create a harmonious and visually appealing presence with the iris.

Such perennials are Peonies, Daylilies, Salvia, Lavender, Coneflowers, Russian Sage, Coreopsis, Yarrow, Siberian Bugloss, Balloon Flower, Roses, Dianthus, and Hostas.

Frequently Asked Questions

Are There Natural Occurring Blue Roses?

No, they don’t exist in nature. 

There isn’t a naturally occurring blue rose. 

Most of the ones you see are man’s interventions through genetic modification, dyeing, or breeding programs.

Is It True The Soil pH Can Change The Color Of Flowers?

Yes, it can. Expert gardeners use this science to tweak and influence the shades of flowers. 

However, not all blue flowers bow to the rule of pH change. But one loyal plant that always will is the hydrangeas. 

They are shifters and will change to blue or purple in acidic soil. Meanwhile, alkaline soil makes their bloom red or pink. 

Are There Naturally Blue Flowers?

Yes, there are TRUE or NATURALLY occurring blue flowers, but they remain a rarity in the plant kingdom. 

The most commonly seen ones are camouflaged through breeding programs and genetic modification.

However, some prestige plants with TRUE blue blooms are Gentian, Cornflower, Delphinium, Blue Flax, Plumbago, Balloon Flower, and Heavenly Blue Morning Glory.

How Can I Design A Garden With Blue Flowers?

There are many different ways to do this. And the simplest way is to make a focal point in your garden with it. 

Plant a HUGE blue-flowering tree, shrub, or plantation of blue bloomers like Irises or Delphiniums in the heart of the garden as an anchor feature. 

Be clever with complementary colors, layering, and height differences from companion plants to make it even more compelling. 

You can sprinkle shades of white, yellow, or pink bloomers alongside them to spark a terrific contrast and balance. 

Conclusion

In conclusion, you can use any blue perennial flowers discussed in your garden design. 

Moreover, they keep gifting your outdoors with generous blooms year after year.

But bear in mind each of these flowers has its demands. That is why it is crucial to research their soil type, climate conditions, sunlight, watering requirements, and the companion plants you choose.

Each of these factors plays a massive role in the overall health or survival of the plant. 

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