Shasta daisies (Leucanthemum x superbum) have long been garden favorites, valued for their cheerful white flowers that bloom for a long period. Besides the classic, yellow-eyed daisy form, there are cultivars with crested, frilly, double, and semi-double blossoms. In recent years, a number of new cultivars have come on the market with improved flower production.
To help gardeners select the best ones from among the many choices available, the Chicago Botanic Garden evaluated 25 cultivars of Shasta daisies, along with two cultivars of the related oxeye daisy (Leucanthemum vulgare), over a seven year period in their zone 5 gardens. Plants were given minimal maintenance in line with what they might receive in home gardens. They were cut back at the end of the summer to rejuvenate the foliage and were mulched over the summer growing season, but received no protective mulch in the winter. Plants were evaluated for traits such as flower production and durability of bloom, the health and vigor of the plants, and resistance to insects, disease, and winter injury.
Many cultivars performed well, but two Shasta daisies were five-star "excellent" standouts: 'Becky', with 3 1/2-inch, single flowers from early July to early September on a 40 inch tall plant and 'Amelia', a seed-grown cultivar with 5-inch flowers and strong stems that bloomes from mid-June to early August. Quite a few other cultivars received a four-star "good" rating, including 'Snowcap', 'Snowdrift', 'White Knight', and 'Switzerland'.
Both of the oxeye daisy cultivars evaluated received the top, five-star rating: 'Filigran', 26 inches tall with 2-inch flowers in bloom from mid-May to early July, and 'Maikonigin', 36 inches tall with 3-inch flowers in bloom from late May to late July.
Shasta daisies do best in full sun and fertile, well-drained soil. They won't tolerate wet feet, especially in winter, and are likely to develop crown rot if buried under a heavy winter mulch. Some of the tall varieties may need staking, especially if grown in part sun. Deadheading will prolong bloom; when bloom finishes, cut flower stalks down to the basal cluster of leaves.
To see the entire daisy evaluation report, go: Chicago Botanic Garden.