Add garden beauty with cool season annuals
URBANA, IL – Gardeners looking for high-performing cool-season annuals should consider alyssum, nasturtium, Swiss chard, snapdragon, pansies, and ornamental kale, according to Nancy Kreith, a University of Illinois Extension horticulture educator.
“These annuals bring beauty to a spring garden and most benefit pollinators looking for food after a long winter,” she says. “Chard and kale, which don’t have significant blooms, certainly have colorful foliage and are suitable for human consumption. Humans also enjoy consuming the tasty flowers of nasturtium and Viola sp. These annuals can be planted in the ground or in containers, if you’re lacking garden space.”
Alyssum (Lobularia maritima) is a full-sun to part-shade plant that grows 3 to 6 inches tall. It prefers moist, well-drained soil and works well as a border or in rock gardens. Colors include pink, purple, white, and yellow. Often, self-sown seedlings appear the following year. The blooms are a favorite of pollinators.
Nasturtium (Tropaeolum majus) grows best in full sun to partial shade and reaches 8 to 15 inches tall. The trailing types can stretch several feet. Bloom colors include orange, red, yellow, pink, and bi-color. This plant responds well to direct seeding in spring. Seeds should be scarified before planting.
Swiss chard (Beta vulgaris var. cicla) is a cool-season leafy vegetable that grows up to 24 inches tall and prefers full sun. It can be direct-seeded into rich, well-drained soil, and soaking seeds overnight will aid in germination. Many cultivars come in magnificent colors of red, yellow, orange, and pink. Be on the lookout for ‘Ruby Chard,’ ‘Rainbow Chard,’ and ‘Rhubarb Chard’ cultivars, as they will be sure to add texture and color to the garden.
Snapdragon (Antirrhinum majus) requires full sun and range in height from 6 inches to 3 feet. It prefers moist, well-drained soil and is very cold-tolerant. It can be planted in spring and again in mid to late summer. Shorter varieties serve as great borders and taller varieties work well as a centerpiece or background. Blooms can be range from pink, purple, red, white, yellow, to bi-color.
Pansy, Viola (Viola x writtrockiana) is a full-sun to part-shade plant maturing at 6 to 12 inches tall. It prefers moist, well-drained soil and blooms include blue, peach, red, white, yellow, and bi-color. Some of the newer cultivars and many of the viola (smaller flowers) have the ability to overwinter with light protection.
Ornamental kale (Brassica oleracea) prefers full sun and moist, well-drained soil. It grows 12 to 24 inches in height. Like chard, this will add color and texture to the garden with its unique foliage. Leaf colors range from red and green, to solid blue, to white and green. Two cultivars to look for are ‘Nagoya Garnish Red’ and ‘Redbor.’
Cool season annuals can be planted in early to mid-spring. They thrive in cooler temperatures. As the heat of summer comes, most of these will look ragged. Alyssum plants can be rejuvenated by cutting them back to the ground. If you do not have the patience to wait for them to re-bloom, they can be replaced by warm season annuals. Nasturtium are unique in that they last from spring to fall. Chard and kale can be refreshed by harvesting the outer, mature leaves. The center point will continue to grow fresh leaves all season.
In Illinois, gardeners should take advantage of the changing of the seasons. “This spring, plan for getting a jump start on the growing season by incorporating cool-season annuals in your landscape,” Kreith says. With a little effort, your yard will be looking colorful well before much else is beginning to show.