Daylilies are a common flower that is considered to be hardy in many U.S. Department of Agriculture planting zones, even in colder climates of zone 4, where winter temperatures can reach minus 30 F. Daylilies are characterized by their green spiky foliage and large blooms that come in a variety of different colors. They typically bloom several times throughout the growing season, unlike other lily varieties, and will return year after year.
The Black Eyed Stella is a hybrid of the popular Stella d’Oro daylily, and both are hardy in zone 4. Resistant to daylily rust and many pests, this daylily also features a compact root system, making it ideal for containers as well as erosion control. The Black Eyed Stella blooms as many as five times a year in zones 9 to 11, but should bloom at least twice in zone 4. The blooms are typically 2 to 3 inches in diameter and the stalks will reach a height of just under 2 feet.
The Mary Todd daylily is another yellow variety that is hardy to zone 3. In fact it appears to like colder climates better than warm and it is not recommended that this variety be grown in zones warmer than 8. It is one of the first daylilys to bloom during the season but often does not rebloom. While it is possible to see it rebloom in zone 4, it is not likely. The blooms on this plant will be approximately 6 inches across and the stems can reach a height of up to 32 inches.
Buttered Popcorn is a late-season bloomer, often having blooms appear in the middle of summer. However, it will continue to rebloom often until the first frost. This particular variety can tolerate the colder climate in zone 4 and also does well in extreme heat found in hotter zones. Each plant will have several blooms that will range in width to about 6 inches across. The stems will typically reach a height of 33 inches at maturity.
One of the few red varieties of day lilies, the Frankly Scarlett can be grown from Zones 3 to 11. It doesn’t mind extremes in temperature and is considered to be very hardy and disease resistant. The blooms are typically 3 inches across and several will appear on the same plant. At maturity, the stems of this plant should reach at least 2 feet in height. In zone 4 this plant will typically bloom twice, but in warmer zones it will actually bloom up to eight times per season.