Summer blooming perennials

Pretty Purple Ironweed

Here is another easy plant for all gardeners who like purple. Vernonia noveboracensis (pronounced ver-NOH-nee-ah no-vee-bor-ah-SEN-sis), “New York Ironweed” is ideal for hot, humid climates. Please don’t confuse this one with Veronica, a totally different plant.

Ironweed is tall and narrow. It has large clusters of tiny purple flowers mid-summer to late fall. The flowers attract butterflies and bees, so it is perfect for the back of a pollinator garden.  It blooms best in full sun, but will also tolerate half-sun. If the spent blooms are pruned away, the plant frequently will branch and re-bloom. If you forego the deadheading, finches and other seed-loving birds will visit to remove the seeds for you. Mine have occasionally reseeded. Baby plants are easy to relocate.

Ironweed prefers an acidic soil, so don’t bother with lime. They like moist soils that are high in organic matter, but will tolerate less water. Mine are planted in heavy clay soil and do well. The plant’s tolerance for varying moisture levels means it will do well in rain gardens.

Left alone, Ironweed will reach 6 to 8 feet in height. This is a little too tall to fit into the garden beds in the Mary Snoddy garden, so I cut it back by half in mid-May. This delays the flowering a bit, but the plant branches where it is cut back, so I end up with more flowers than if I had left it unpruned. The brilliant purple blooms pair well with most other colors. In this year’s annual bed, I grouped it with Melampodium, a wonderful annual that I will write about next week.

Ironweed dies completely to the ground in freezing weather.  The dead stems should be pruned off. It is perennial in most of the US (zones 5a to 9b). This one looks equally at home in mixed borders and wildflower plantings. Highly recommended!

Long-blooming Purple Coneflowers

Most perennials have shorter bloom periods than summer annuals. One that flowers for a lengthy time is Echinacea purpurea, Purple Coneflower.  In upstate South Carolina, the first blooms open in late spring (just after Mother’s Day) and continue all the way to frost. Purple was the original color of this prairie native that has been adapted to garden use. Hybridization expanded color choices to rose, orange-red, yellow, pink, magenta,  white and green. The Latin name came from the Greek word echinos, meaning hedgehog, a reference to the spiky orange central cone. The coarse leaves are a bit rough.

Coneflowers prefer full sun. They are heat resistant and will tolerate moderate drought. They are adaptable to various soil types and will grow in zones 3 to 9. They rarely need fertilizer. Cultivars vary in height but average 3-4 feet with a 2-3 foot spread.

Bumblebees and butterflies flock to the flowers. Blooms are long lasting, either on the plant or as cut flowers. Deadheading keeps the plant neater and forces fresh buds to form. I stop deadheading in autumn and allow the spent flowers to remain through winter, offering a seed treat to finches and other birds.  Any uneaten seed self-sow for new plants in the spring but the seeds of cultivars may not be like their parent plants. Seedlings are easily transplanted. Cut dead leaves and stems to ground level in late winter before spring growth begins.

Deer ignore coneflowers but rabbits find them tasty. They are rarely damaged by insects or diseases, but may show occasional damage from aphids, Japanese beetles, powdery mildew or bacterial leaf spots. I have experienced an occasional problem with “aster yellows” but promptly removed the affected plants to avoid a spread to neighboring plants. My two favorite cultivars are ‘Magnus’ which has large, light purple blooms and ‘Kim’s Knee High’ which is only a foot tall. Both look best when planted in masses rather than as single plants.

A bumblebee busy on a ‘Magnus’ coneflower bloom.

A bumblebee busy on a ‘Magnus’ coneflower bloom.

A group planting.

A group planting.

Note the weird green buds inside the purple circle. These deformed blooms are a symptom of Aster Yellows. Remove and destroy the plant to prevent the spread. Aster yellows is a bacteria-like organism called a phytoplasma. It is spread by leafhoppers.

Note the weird green buds inside the purple circle. These deformed blooms are a symptom of Aster Yellows. Remove and destroy the plant to prevent the spread. Aster yellows is a bacteria-like organism called a phytoplasma. It is spread by leafhoppers.