Delicate white petals and a sunny yellow "eye" are the hallmarks of the Shasta daisy (Leucanthemum x superbum). This hardy perennial grows almost anywhere in the United States, making it a good choice for a ground cover or garden border. Because the cut flowers can last up to 10 days, Shasta daisies also are popular additions to floral arrangements.
American horticulturist Luther Burbank created the Shasta daisy in 1901. The plant is a quadruple hybrid that Burbank developed from the wild oxeye daisy, the English daisy, Portuguese daisy and the Japanese field daisy. It took Burbank 17 years to reach his goal of creating a daisy that would have large, pure white flowers and long-lasting blooms. He also wanted to create a plant that could thrive in gardens and double as a cut flower. He named the new variety after snow-covered Mount Shasta in northern California. Today, 69 cultivars of the Shasta daisy exist, according to Richard G. Hawke, plant evaluation manager for the Chicago Botanic Garden.
Shasta daisy plants grow to about 1 to 3 feet high, although some varieties can reach up to 5 feet. They are usually taller than their European cousin and ancestor, the oxeye daisy (Leucanthemum vulgare). The oxeye daisy also has white and yellow flowers and green leaves, but both the flowers and leaves are smaller than the Shasta's. The oxeye also blooms about a month before the Shasta daisy. Although the oxeye daisy is also a popular garden plant, you can also spot it growing wild along roads and in fields.
Shasta daisies share characteristics with other flowers in the Aster family (Asteraceae). They have petal-like florets arranged in rays surrounding a disc floret. In the case of the Shasta daisy, the ray florets are white and the disc floret is yellow. The ray florets can form one or more layers, depending on the variety. The flowers range from 2 to 5 inches across. The flowers bloom from spring through summer, reaching their peak in June and July.
The leaves that grow at the base of the Shasta daisy plant are dark green and thick and measure about a foot long. The leaves on the flowering stems are smaller and grow more sparsely than the basal leaves. Shasta daisy leaves can stay green year-round, depending on the winter climate.
Shasta daisies can grow in a variety of light conditions, from full sun to partial shade. They require fertile soil that drains well. Wet or poorly drained soil will limit growth or harm the plants. If you are growing Shasta daisies from seed, the seeds will take 15 to 30 days to germinate. Sow the seeds at a depth of 1/16 of an inch and keep the soil temperature at 70 degrees F.
In the winter, cover your Shasta daisy plants lightly with pine needles or leaves to protect the crowns but still allow them to get air and light. Heavy mulch or too much cover can cause crown rot. You can also divide clumps of the plants every few years to encourage vigorous growth. Deadhead spent blossoms so that your plants will keep flowering and produce seeds, advises Richard Hawke of the Chicago Botanic Garden.