Black-eyed Susans (Rudbeckia hirta) are cheerful daisy-like flowers with bright or golden yellow petals. They are extremely popular in flower gardens. Native to central and eastern North America, they’ve been naturalized in the western regions of the continent as well. According to the Ontario Wildflowers website, black-eyed Susans now grow in almost every Canadian province and American state. The only exceptions are the northern Canadian territories, Arizona, and Nevada.
The plants are a valuable addition to any butterfly garden. The foliage is a food source for the larvae of bordered patch, Gorgone checkerspot, and silvery checkerspot butterflies. The blossoms attract many different pollinators, including several butterfly species.
Recognizing Black-Eyed Susans
With their colouring, it’s not surprising that black-eyed Susans are part of the sunflower family. They have bright or golden yellow petals that surround a dark brown centre cone. Black-eyed Susan blossoms are very similar in shape to coneflowers.
According to the Prairie Pollination website, the foliage of black-eyed Susans is covered with bristly hairs, making it feel rough and coarse. Leaves are slightly greyish in colour and oval or lance-shaped. They alternate along the stem and are larger at the base of the plant, diminishing in size near the top. The stems usually grow 30-60 cm tall and may grow in small clumps (up to four). Each stem produces a single flower, blooming in late summer or fall. They are technically biennials and will flower in their second year. However, because black-eyed Susans are prolific self-seeders, they appear as perennials.
A very common garden plant, Rudbeckia hirta also grows naturally in a variety of sunny, open habitats, including prairies, plains, meadows, pastures, roadsides, and at the edges of forests.
Growing Black-Eyed Susans
These bright and cheerful flowers are very easy to grow. They spread naturally by self-seeding. Replicating that natural process is a simple way to add the plants to your own garden.
The Lady Bird Johnson Wildflower Center explains how to collect seeds from spent flowers. The seeds are mature about 3-4 weeks after the blooms die back. But, they’re easier to collect a bit later when the seed cones dry further, becoming loose and less compact. If storing the seeds for spring planting, keep them refrigerated in an air-tight container.
It’s easiest to simply sow the seeds directly into the garden in the fall. Rake them loosely into the soil, or cover lightly with 0.5 to 1.25 cm of dirt or mulch. In dry weather, keep the soil moist until the seeds germinate, which usually takes 1-2 weeks.
For spring planting, seeds need to be cold stratified in order to imitate natural weather conditions. But since black-eyed Susan seeds are best stored in the refrigerator, stratification will take place during storage. Once the last frost date has passed, plant out as directed for the fall: cover loosely with soil and keep moist until germination.
In a piece at The Spruce, Marie Iannotti explains that black-eyed Susans aren’t picky about garden conditions. They do best in warm spots with full sun but will tolerate partial shade. While they require moisture to germinate, once they’re established, they are drought-resistant. They prefer soil that isn’t too rich; there is no need to fertilize them. The only real care they require is deadheading, to keep volunteer plants in check.
Black-Eyed Susans and Butterflies
Black-eyed Susans are a terrific addition to any butterfly garden. They provide a food source for the larvae of three different butterfly species, which are described by the Butterflies and Moths of North America website:
- Bordered Patch (Chlosyne lacinia)
- These butterflies are usually orange and black with a wide cream band down the centre of the upperwings. They are found in the southern regions of the United States, from Nevada and California in the west to Kansas and Arkansas in the east.
- Gorgone Checkerspot (Chlosyne gorgone)
- These black and orange butterflies are found throughout the central United States. They may also be spotted in the far southern regions of Alberta, Saskatchewan, and Manitoba.
- Silvery Checkerspot (Chlosyne nycteis)
- These butterflies have black and orange upperwings with white crescents along the edges; and a lighter underside. They are primarily concentrated east of the Great Plains in the United States. There have been spottings further west in the U.S.A. as well as in the far southern regions of Ontario, Quebec, and the maritime provinces in Canada.
According to the Prairie Pollination website, black-eyed Susans are also an important source of nectar for many different species of butterflies. In fact, some entire families of butterflies are pollinators for the flowers, including:
- Skippers (family Hesperiidae)
- The Canadian Biodiversity Information Facility website states that skippers are small to medium in size and are have dull grey and brown markings. They are so-named because their flight involves skipping from place to place. There are about 300 species in North America including 72 species in Canada.
- Whites and Sulfurs (family Pieridae)
- The Butterflies and Moths of North America website lists 97 different species and subspecies of whites and sulfurs. These butterflies are found worldwide.
- Orangetips (genus Anthocharis )
- True to their name, most orangetips have orange spots on the tips of their forewings. The Learn about Butterflies website explains that there 17 different species of orangetips, with seven of those located in North America.
- Brush-footed butterflies (Family Nymphalidae)
- The Canadian Biodiversity Information Facility states that there are more than 5,000 species of brush-footed butterflies found throughout the world. Well over 200 of those species are native to North America.
- Gossamer-winged butterflies (family Lycaenidae)
- According to the Prairie Pollination website, 63 species of gossamer-winged butterflies are found in Canada but many of those are rare. This family includes harvesters, coppers, hairstreaks, and blues.
Black-eyed Susans are one of the best native flowers for a butterfly garden. The plant attracts numerous different species of butterflies, both as a larval host and as a source of nectar. Additionally, the flowers are bright and cheerful self-seeders that are easy to grow. If you don’t already have black-eyed Susans in your garden, why not start some from seed this coming season?
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