Gentian flowers (Gentiana L.) grow wild in a range of habitats across several continents, blossoming in a rainbow of colors, such as blue, red, yellow and pink. They are members of the Gentianaceae plant family. North America natives include pleated gentian (G. affinis), Rainier pleated gentian (G. calycosa), G. sceptrum “King’s Scepter” and G. setigera “Mendocino.” These perennial varieties grow in U.S. Department of Agriculture plant hardiness zones 8 through 10.
Pleated gentians, also known as northern gentians, thrive in the cool mountain air and moist soil of open grasslands. Clusters of up to 10 vivid blue flowers burst into bloom atop 16-inch stems. The sides of each 1-inch-long blossom are folded, or pleated, and the stems grow in clumps of 12 or more, bearing as many as 13 pairs of evenly spaced leaves. Bumblebees find pleated gentians especially appealing.
Rainier Pleated Gentians
Pale to deep-blue in color, with occasional green speckles, the blossoms on Rainier pleated gentians emerge in summer and fall, preferring partial shade and soil that is moist and cool. A single funnel-shaped flower or as many as three grouped together bloom at the tips of stems that reach to 8 inches tall. Green, oval-shaped leaves grow to about 1 inch in length. Bumblebees are drawn to Rainier pleated gentians, but this variety contains toxins that may be poisonous to humans.
The erect stems on King’s Scepter gentians grow in clumps, reaching up to 2 feet or more. Each stem tip boasts several bright blue flowers with petals streaked in green. Bumblebees love the tubular-shaped blossoms, which bloom in summer and early fall. King’s Scepter gentians grow well in lowland gardens, in wet or moist soil and partial shade.
Named for a county in California where they grow, Mendocino gentians bear blue flowers with 2-inch-long, tapered petals. Clusters of oval-shaped leaves spread open atop slanted, leafy stems, as well as at the base, where they grow to about 3 1/2 inches long. Mendocino gentians flourish in wet mountain marshes and meadows, blooming in August and throughout September.
Gentians can develop leaf spot disease from one or both of the fungi Mycosphaerella andrewsii and Cercospora gentianae. Apply copper or dithiocarbamate spray intermittently for protection against leaf spot disease. Pale brown splotches encircled with darker edges on the leaves may indicate the onset of Botrytis cinerea, or leaf blight. Cankers might also be visible on the plant stems. Remove all affected parts and destroy. Yellow spots that initially appear on basal leaves could be a sign of the fungal rust disease called Puccinia gentianae. After the rust pustules rupture, the spots turn dark brown. Remove and destroy infected plants.
Snails and slugs inflict damage on gentians, munching on flowers, leaves, stems and roots and leaving behind a slimy trail. Handpick and destroy these bothersome pests directly from the plants. Bait a trap using a jar lid filled with beer. Bury the lid with the sides level to the ground. Snails and slugs lured by the beer will fall into the lid and drown. Fashion a barrier around plant beds with a 1-inch or wider copper band. The copper together with the slick secretions left in the wake of the creeping snails and slugs creates an electrical current that leads to the demise of the pesky critters.
Your Planting Articles
- Rutgers University: Gentian Research Network: What Are Gentians?
- Lady Bird Johnson Wildflower Center: Native Plant Database: Gentiana Affinis
- Lady Bird Johnson Wildflower Center: Native Plant Database: Gentiana Calycosa
- Lady Bird Johnson Wildflower Center: Native Plant Database: Gentiana Sceptrum
- U.S. Department of the Interior: Bureau of Land Management: Mendocino Gentian
- USDA Natural Resources Conservation Service: Plants Profile: Gentiana Affinis
- USDA Natural Resources Conservation Service: Plants Profile: Gentiana Calycosa
- USDA Natural Resources Conservation Service: Plants Profile: Gentiana Sceptrum
- USDA Natural Resources Conservation Service: Plants Profile: Gentiana Setigera
- Northern Prairie Wildlife Research Center: Native Wildflowers of the North Dakota Grasslands: Northern Gentian (Gentiana Affinis)