3 Red Perennials for Gorgeous Late-Summer and Fall Color

Author:

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

In September, Persicaria affinis displays a beautiful mix of pink and red flowers. Wait until you see what it does in October...
Rachel Darlington

Best Late-Flowering Red Perennials

Today I want to tell you about three late-flowering red perennials that I'm sure you're going to fall in love with. If you have boggy conditions, then choose the lobelia. If you have dry conditions, then go for the persicaria. And if your soil is somewhere in between, then why not choose the monarda?

The dark foliage of Lobelia cardinalis is almost as enchanting as its bright-red flowers.
Rachel Darlington

1. Cardinal Flower (Lobelia cardinalis)

My first plant is the moisture-loving Lobelia cardinalis. There are several varieties with glorious purple foliage, such as 'Queen Victoria' and 'Elmfeuer', and the dark foliage is as much a selling point as their glorious blood-red flowers.

This award-winning plant produces spires of red flowers, which are three to four feet tall from mid to late summer.

Lobelia cardinalis makes for a fun addition in a mixed border.
Rachel Darlington

How to Grow Cardinal Flower

Grow in deep, fertile, reliably moist soil in full sun or partial shade. Lobelia cardinalis 'Queen Victoria' is suitable for US hardiness zones 3 to 9.

Planting Monarda 'Cambridge Scarlet', commonly known as bee balm, is a great way to attract pollinators to your garden when most other flowers have faded.
Rachel Darlington

2. Bee Balm (Monarda 'Cambridge Scarlet')

Another beautiful red flower in late summer is the bee balm or Monarda 'Cambridge Scarlet'. I love the quirky, shaggy flower heads of this plant. Bee balm reaches about three feet and acts as a complete magnet for bees and butterflies.

How to Grow Bee Balm

Grow at the front or middle of a border in fertile, moist, well-drained soil in full sun or part shade. 'Cambridge Scarlet' is suitable for hardiness zones 4 to 9.

Compared with the photo at the top of this article, you can see the striking red of Persicaria affinis in October—not many pink blooms left to be found!
Rachel Darlington

3. Knotweed (Persicaria affinis)

My final plant—Persicaria affinis—can be used at the front of a border, but also does well on a bank. This mat-forming plant starts flowering in early summer with pale pink spires, but by September, these have matured to a deep russet red. The combination of pink and red spires together is quite magical.

How to Grow Knotweed

The plant is unfussy about soil, although it doesn't like boggy conditions and prefers full sun or partial shade. It's suitable for US zones 3 to 8.

More Late-Summer Flower Inspiration

Best Pink Perennials for Late Summer Color
Late-summer bloomers like swamp lily and gladiolus will add a brilliant pop of pink to your garden when most other flowers have already faded.
Gorgeous Late-Flowering Blue Perennials for Your Garden
Late-blooming beauties like agapanthus and globe thistle add swaths of dreamy blue to your garden after most other pops of color have faded.
3 Gorgeous White Perennials That Bloom in Late Summer
Japanese anemone is just one of several late-flowering perennials that can add a striking pop of white to a fall garden.