How to grow cardinal flowers – for a native perennial with striking crimson blooms

Cardinal flowers, Lobelia cardinalis, are striking perennials with crimson-red flowers. Native to parts of North, South and Central America, cardinal flowers are typically found growing in fertile, moist areas, often seen along riverbanks, marshlands, and at the edge of woodlands.

Famed for producing scarlet flower spikes, this plant is often considered among the best perennials to grow, particularly for those gardeners seeking native species that add impact and color to front and back yards.

Cardinal flowers are short-lived perennials that often only last 2 to 3 years. They are, however, prolific self-seeding flowers, meaning that one clump will produce plenty of seeds that will become future plants for your borders. Here, perennial plant experts provide growing advice on how to grow cardinal flowers in your yard, for a bounty of red flowers during spring and summer.

How to grow cardinal flowers

Cardinal flowers are renowned for their red flowers, and it is not just gardeners who seem to adore these blooms. As with other native flowering plants, cardinal flowers are popular with hummingbirds, bees and butterflies, attracted by the open, two-lipped flowers that encourage pollinators to stop and feed. If you are seeking native perennial plants for pollinators, cardinal flowers should be at the top of your garden wish list.

Things to know about cardinal flowers

'Cardinal flowers are popular blooming perennials that are often planted to attract hummingbirds and butterflies,' says perennial plant expert Katie Sunderlage. 'It is important to know that this plant is very hardy, and can be grown from US hardiness zone 3 to US hardiness zone 9.'

Cardinal flowers are considered part-shade perennials, growing best with at least some sunshine every day. While they can be grown in shady areas, there may not be as many blooms if sunshine is scarce.

'It’s recommended that gardeners in cooler zones plant cardinal flowers in sunny spots, but in warmer climates, I would suggest a shadier corner of the yard,' Katie adds.

'The important thing to remember is that for your perennial to thrive, you must keep the soil moist,' Katie says, 'as this will promote blooms.' If soil is allowed to dry out, cardinal flowers may not bloom.

Katie also advises that 'cardinal flowers are generally disease and pest resistant, as is often the case when growing native species.' So, if you are looking for a low-maintenance and easy perennial to plant, cardinal flowers might be just what your yard needs.

Katie Sunderlage

Operations Manager at Holland Group, managing the customer service department and purchasing. Katie has been in the green industry since 2005 in the Greater Milwaukee area, earning her degree in Horticulture in 2008. She has been able to share her love for plants working in multiple garden centers, in sales positions and most recently in an online retail platform at Holland Group.

Growing advice for cardinal flowers

• Soil: 'It’s important to keep soil evenly moist to promote blooms,' Katie says. 'If the surrounding soil is allowed to dry out, your plants may not flower.' To help improve soil health, I would recommend mulching your borders, including around the base of your perennials, to help keep moisture in the soil. Mulch is available to buy from garden stores or online, such as this organic mulch from Amazon.
• Light: Cardinal flowers are generally considered part-shade perennials, growing best in areas where they can enjoy moderate amounts of sunshine, but are protected from the heat of the day. 'They can tolerate shady areas,' Katie adds, 'but in darker corners, there may not be as many blooms for you to enjoy.'
• Watering: Cardinal flowers prefer moisture-retentive soil, growing best in wet and damp spots, such as along streams or in rain gardens. 'They grow best in damp soil but also enjoy areas with high humidity,' Katie adds. 'They are a moisture-loving plant and will not only draw in moisture from the soil but also from the air.' It is best to regularly water newly planted perennials in the first few months to ensure they have enough moisture to establish healthy roots, but once fully grown, they should be able to get what they need from the soil.
• Fertilizing: 'Generally speaking, cardinal flowers do not need fertilizing throughout the year,' Katie says. 'I would recommend applying organic matter or compost to your borders annually, to improve the quality and fertility of your soil. Doing so in late winter will provide a little boost of energy to help the plant come out of dormancy.'
• Deadheading: 'Spent blooms can be removed throughout the season to keep the plant looking neat and tidy,' Katie says. 'Regular deadheading will promote more blooms, however, do not cut all flower stems to ensure that some seed to produced.' It is important to remember that cardinal flowers are self-seeding, so it is a good idea to leave one or two flower stems to produce seeds, to ensure a continuous supply of new perennials for your yard.
• Planting: 'The best time to plant cardinal flowers is in spring,' Katie says. 'They can be grown by seed, bare root, or by an established starter plant.' If starting by seed or bare root, 'it’s a good idea to start them indoors early in the spring to ensure a root system is well established before transplanting outdoors.'

FAQs

Can you grow cardinal flowers in a pot?

While it is not impossible to grow cardinal flowers in a pot, it is generally not recommended. This is because this perennial prefers damp, moist soil, and the soil in containers can dry out very quickly in the summer months. Consider growing alternative perennials that are more suited to pots, such as astrantia or echinacea.

Learning how to grow cardinal flowers is a great way to incorporate native flora into your yard. With attractive red blooms, your borders will be full of color and humming with pollinators. For more red flowering planting ideas, see our guide on how to grow a bottlebrush plant.