There are nine classes of lilies, according to the North American Lily Society, and all of them are lovely. But, for northern gardeners, the two most commonly planted classes are the Asiatic and Oriental lilies — both of which are great plants for northern gardens.
Both types perform well in the garden, if given full sun and well-drained soil, but the Asiatics are generally considered the easier group to grow. (For a discussion of the differences between Oriental and Asiatic lilies, see this blog post from a Canadian gardener. The tips on how to know what you have are especially useful.) One interesting difference between the two types is that while the blooms of the Asiatics generally face upward, the Oriental hybrids more commonly face sideways.
Asiatic lilies are rock-solid hardy in Minnesota. You can plant them early in spring and will get flowers that summer and for many summers afterward. They generally grow 1 to 4 feet tall and begin blooming early in the summer. A little fertilizer in the spring and again in June or July will keep the bulbs healthy and blooming. Asiatic lilies come in a wide range of colors — red, orange, yellow, pink, white. ‘Enchantment’ is a popular orange variety that blooms in June. Many Asiatic lilies are unscented.
Orientals struggle in some Minnesota gardens, while doing beautifully in others. These are the lilies with that distinctive lily fragrance that some gardeners adore (others are revolted by it). They grow best in full sun (perhaps in a sheltered location) with light, well-drained soil. They generally grow 2 to 5 feet tall and will create a clump about 2 feet wide. ‘Stargazer’ lily is one of the most popular (and hardy) Oriental hybrids, though this type comes in a variety of pastel shades as well as beautiful whites.
Two final notes about lilies: Each year, MSHS has a bulb sale at the Minneapolis Home and Garden Show (we’re in room 103). There is a great variety of healthy bulbs available and many knowledgeable volunteers there to answer questions. Stop by during the show, which is being held Feb. 27 to March 3, 2013. Second, if you are interested in learning more about lilies, you can’t go wrong by checking out the North Star Lily Society. This group includes many Minnesota lily hybridizers and enthusiastic growers. NSLS has a bulb sale every fall and a lily show each summer. Check out its website for more information.