The brown-eyed susan, a member of the aster family, is a prolific late summer wildflower loved by pollinators. Its botanical name is Rudbeckia triloba, referring to the three sections of its leafy stems, and it is sometimes confused with the more common black-eyed susan. There are a few differences between them: brown-eyed susans flower a bit later and bloom for a longer period of time, grow much taller (up to 5 feet), and have smaller blooms than black-eyed susans. Black-eyed susans, on the other hand, form clumps with stems and flowers growing from the center, have many branches, and have a bushier appearance. The flowers themselves also have a slightly more rounded petal edge. These reliable plants often bloom in profusion, creating a very showy display.
These colorful flowers are biennial and reseed themselves effectively in many different habitats, including roadsides, vacant lots, meadows, and along riverbanks and railroad tracks. Some wildlife eat them, including rabbits, deer, and groundhogs. They're fairly drought-tolerant, but they may droop or dry out if there is a prolonged dry spell. They make a good filler for large cottage style gardens that need a boost of late summer color, and look fabulous alongside deep red day lilies and the cool blues of caryopteris. These bright yellow beauties stay in bloom for many weeks, often into the autumn.
|Botanical Name||Rudbeckia triloba|
|Common Name||Brown-eyed susan, thin leaved coneflower|
|Plant Type||Biennial, short-lived perennials|
|Mature Size||Up to 5 ft. tall|
|Light Exposure||Full sun to part sun|
|Soil Type||Fertile, loam, tolerates clay and gravel|
|Soil pH||Slightly acidic|
|Bloom Time||Mid to late summer, often blooms until fall|
|Flower Color||Bright yellow|
|Hardiness Zones||3 through 10 (USDA)|
|Native Areas||Eastern US and Midwest, south to Texas|
Brown-Eyed Susan Care
These wildflowers are very easy to grow and easy to maintain once established. Other than watering occasionally and deadheading as needed, there's not much to do but enjoy their vibrant color in your garden. If they get very tall they may need a bit of support to keep the flowers visible and upright, but they will also rest upon the foliage of other plants in a more crowded cottage style garden.
Brown-eyed susans prefer full sun but will adapt to part shade fairly readily. Afternoon sun is brighter than morning sun so this might be a consideration if deciding where to plant them.
Ideally these flowers prefer a loamy soil, but they're not very fussy and will spring up readily in areas with poor soil. This makes them a good choice for those spots in your yard with clay soil or rocky soil.
They are quite drought-tolerant, but if a long dry spell makes them droopy or sad, give them a good drink of water.
Temperature and Humidity
The brown-eyed susan tolerates a wide range of temperatures, being hardy from Zones 3 to 10, and may continue to flower after a light frost in late autumn. They do well in hot, dry conditions. When growing in the wild, you are unlikely to find them in humid areas such as swamps.
Once the flowers are spent, trim them off to keep this plant looking tidy in your garden. As it gets later in the season the foliage may get a big leggy and unattractive, so prune and deadhead as needed. You can cut this plant all the way back to the ground at the end of the season.
How to Propagate Brown-Eyed Susan
These prolific flowers grow very easily from seed (which may be collected in late summer) and can be sown outdoors in spring or fall. They may also be divided and transplanted; this is best done before or after the blooming season in early spring or late fall.