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Gorgeous Late-Flowering Blue Perennials for Your Garden

Rachel is a passionate plantsperson, YouTuber and author living in Ireland. She grows a wide range of hardy subtropical and tropical plants.

Late-blooming beauties like this agapanthus will add swaths of dreamy blue to your garden after most other pops of color have faded.

Late-blooming beauties like this agapanthus will add swaths of dreamy blue to your garden after most other pops of color have faded.

Dreamy Blue Perennials for Late-Summer Color

Everyone loves blue flowers, so why not plant a few that will bloom all the way into the fall? These late-blooming blue perennials will add beautiful color to your garden when most other flowers have already disappeared for the year.

Echinops bannaticus, more commonly known as globe thistle, makes for a beautiful late-summer bloom in the garden.

Echinops bannaticus, more commonly known as globe thistle, makes for a beautiful late-summer bloom in the garden.

1. 'Blue Glow' Globe-Thistle (Echinops bannaticus)

My first plant is the blue globe thistle, which makes a fantastic statement at the back of the border. It has spherical blue-gray flower heads that are produced from mid- to late summer. When the light catches them, they can be quite magical.

Tips for Growing Globe Thistle

A great and easy plant for either an exposed or sheltered site, it's generally trouble-free, but a few easy care tips will help it flourish.

  • This plant does best in poor, well-drained soil in full sun, although it will tolerate partial shade.
  • Cut withered stems to the ground in spring, but watch out for its prickly leaves.
  • The blue globe thistle is suitable for US hardiness zones 3 to 8.
African lilies come in a variety of shades, from deep blue to white, like this gorgeous violet-tinged Agapanthus 'Queen Mum'.

African lilies come in a variety of shades, from deep blue to white, like this gorgeous violet-tinged Agapanthus 'Queen Mum'.

2. African Lily (Agapanthus)

My second blue flower is the stately African lily or agapanthus. This is a majestic late-summer flower that adds a real architecture to any flower bed. Agapanthus comes in many shades of blue, from inky blues and pale sapphires to purples, and there are even some whites.

Tips for Growing Agapanthus

  • Plant deciduous agapanthus, as they're hardy and their leaves die down in winter. Evergreen forms are more tender and best grown in a pot and brought under shelter in winter.
  • Grow agapanthus in well-drained soil, in full sun.
  • Water regularly and feed in spring.
  • Enjoy the flowers and allow some seed heads to form so you'll have something interesting to look at through winter.

Why Won't My African Lily Flower?

If your plant fails to flower, check it's getting enough sun and that you're feeding it. Failing that, transfer the plant to a pot with a 1- to 2-inch space around the root ball. Some agapanthus need to have their roots constrained to flower.

Though butterflies don't usually like the color blue, they can't resist the blooms on Symphyotrichum ‘Little Carlow’.

Though butterflies don't usually like the color blue, they can't resist the blooms on Symphyotrichum ‘Little Carlow’.

3. Michaelmas Daisy (Symphyotrichum)

My final blue plant for today is the Michaelmas daisy. There are various varieties, but mostly they produce abundant violet-blue, yellow-centered daisies in late summer. They are much loved by butterflies and bees.

Tips for Growing Michaelmas Daisies

  • Grow Michaelmas daisies at the front of a border in moderately fertile, moist soil.
  • Plant in full sun or partial shade.
  • Some varieties, like the stunning 'Little Carlow', may need staking. ('Little Carlow' is hardy from US zones 4 to 9.)

Happy Growing!

So why not add a little blue to your garden with globe thistles, agapanthus or Michaelmas daisies? And if you'd to throw in a color to go alongside all that blue, check out these beautiful late-blooming perennials in pink and white. Happy growing!

© 2021 Rachel Darlington

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