• From the 1960s through the 1990s the agricultural research stations in Quebec and Ottawa in Canada developed rose cultivars with the capability of withstanding the country's cold winters. Explorer roses, all named for Canadian explorers, grow well down to a U.S. Department of Agriculture hardiness zone 2 or 3 with no cold protection. They also have good disease and pest resistance.
  
  

Henry Kelsey

• In 1981, the rose bush Henry Kelsey was developed. A vigorous climber, it can gain a height of approximately 8 feet. The climber benefits from a trellis but is often left to grow with no support. It produces a slightly weeping, floppy growth habit. The flowers are a dark pink and semi-double with exceptional fragrance. Blooming usually begins in mid-July and form large clusters of 9 to 13 flowers. The bush offers repeat blooming. It has disease resistance to powdery mildew and moderate resistance to black spot. The foliage of the bush is a deep, dark green. The rose bush was named after the Henry Kelsey who worked for the Hudson Bay Company in the 1600s.
  
  

David Thompson

• The David Thompson rose bush grows to a height of 4 feet with a width of 4 feet. Developed in 1968, the rose bush offers a moderate growth rate with dark green foliage that takes on a yellowish hue during the fall months. It produces clusters of pink flowers that measure 2 1/2 inches across with yellow stamens. The blossoms are a popular cut flower. It re-blooms throughout the summer months prolifically until the first frost of fall. The canes of the David Thompson rose have very few thorns. During the fall months the bush does not produce hips. A low-maintenance shrub, the rose bush has good disease resistance and requires very little care.The rose is named for David Thompson, a fur trader and geographer in the late 1700s and early 1800s.
  
  

Martin Frobisher

• The Martin Frobisher, bred in 1968, produces 3-inch-wide light pink flowers. The heavily ruffled blossoms have up to 25 petals and produce a strong fragrance. Flowers appear from June to September.The stems have no thorns and darken in green color as the weather grows colder and winter approaches. It rarely produces hips of any significance. The rose bush grows to a height of 6 feet with a width of up to 4 feet. The plant is highly resistant to powdery mildew and somewhat resistant to black spot. The rose bush was named after the English explorer Martin Frobisher who sought the Northwest Passage during the 1500s.