Tulips are favorites of Midwest gardeners, but we often fail to appreciate the diversity of these spring-flowering bulbs. Tulips vary tremendously in flower and plant size, bloom period, shape, and color.
Tulips are grouped into 15 divisions based on shape and origin. Tulips can also be grouped by bloom time. In Iowa, tulips typically bloom from mid-April through May. Divisions can be classified as early, mid-season, or late based on when in that time frame they bloom.
Single early tulips (Division 1) are among the earliest tulips to bloom. The flowers, available in various colors, are produced on strong, 10- to 18-inch-long stems. The flowers of several cultivars have a sweet fragrance. Single early tulips are excellent for rock gardens, beds, and forcing.
Double early tulips (Division 2) produce semi-double to double, peony-like flowers. The flowers, measuring up to 4 inches in diameter, are on strong, short stems. Double early tulips' color range is smaller than most other tulip divisions.
Kaufmanniana tulips (Division 12) are long-lived perennial tulips. In sunlight, the flowers open fully to resemble a star or waterlily. Flower colors include white, yellow, pink, and intermediary colors. The foliage is bluish-green or chocolate-brown striped. The average plant height is 6 to 8 inches. Their compact size makes them good choices for border edges and rock gardens.
Fosteriana tulips (Division 13) produce some of the largest flowers of the genus. They also perennialize well. Fosteriana tulips are also known as emperor tulips.
Greigii tulips (Division 14) are noted for their brightly-colored flowers and purple-striped or mottled foliage. Plant height varies from 8 to 12 inches. Because of their short stature, Greigii tulips are excellent choices for borders or rock gardens. They also perennialize well.
Triumph tulips (Division 3) produce cup-shaped flowers on strong, medium-length stems. The average plant height is 10 to 16 inches. This tulip division is one of the largest and offers the widest range of flower colors. Triumph tulips are short-term perennials, as most cultivars bloom only for a few years. However, they are excellent for forcing.
Darwin hybrid tulips (Division 4) are highly prized for their large, brilliant flowers. Flowers are available in shades of red, pink, orange, and yellow. Blooms are borne on strong stems which are up to 30 inches tall. Darwin hybrid tulips often bloom well for several years, making them one of the better perennial tulips.
Single late tulips (Division 5) incorporates the former Darwin, cottage, and breeder divisions. Along with the Darwin hybrid tulips, they are some of the tallest. Flowers are borne on stems up to 30 inches tall. Flowers are available in a wide range of colors.
Lily-flowering tulips (Division 6) have long pointed petals arching outward, making the flowers resemble a lily. Flower colors include white, pink, red, yellow, and purple. Several cultivars have petals edged or feathered in contrasting colors. Plants grow to a height of 20 to 30 inches.
Fringed tulips (Division 7) have flowers with elegant fringed petals. Many cultivars are mutants of single late tulips. They are also known as crispa tulips.
Viridiflora tulips (Division 8) produce long-lasting flowers with prominent green markings on their petals. The unusual flower characteristics make them interesting additions to the garden.
Parrot tulips (Division 10) have deeply feathered, curled, or twisted petals. Flowers may be single or multi-colored. Many cultivars have a green spot at the base of their petals. Parrot tulips perform best in protected locations as they don't withstand harsh weather.
Double late tulips (Division 11) are often called peony-flowered tulips. The many-petaled flowers are borne on 12 to 20-inch stems. Plant double late tulips in protected locations, as rain and strong winds can damage the large flowers.
Rembrandt tulips (Division 9) produce striped or "broken" blooms. The white, yellow, or red petals are striped with red, bronze, or purple. These types were bought for huge sums during "tulip mania" in Holland in the seventeenth and eighteenth centuries. The unusual markings were actually caused by a virus. Due to the virus, the original Rembrandt tulips are no longer sold. However, several modern, virus-free Rembrandt-type cultivars are available. Bloom time is cultivar specific.
Species and miscellaneous tulips (Division 15) include wild species, horticultural cultivars, and hybrids. Most are short-statured plants. Species and miscellaneous tulips are available in a wide array of colors. They perennialize well and are excellent plants for rock and heirloom gardens. Bloom time is species/cultivar specific and varies from early to late spring. Some species tulips well-suited for Iowa are listed below. Unless otherwise noted, all are hardy in USDA hardiness zones 4 through 7.
- Tulipa batalinii has soft yellow, fragrant flowers appearing in early spring. It grows just 5 inches tall.
- Tulipa clusiana grows 10 to 12 inches tall and blooms in early spring. The flowers have a white interior with a crimson central star and a pink exterior. It naturalizes very well.
- Tulipa linifolia grows 4 to 6 inches tall with brilliant red flowers
- Tulipa pulchella is a tiny plant growing 3 to 5 inches tall. It has violet-purple fragrant flowers in early spring. Hardy in zones 5 to 8.
- Tulipa saxatillis naturalizes readily. The flowers, lavender-pink with a yellow base, appear mid-spring. Plants grow 6 to 8 inches tall.
- Tulipa sylvestris grows 10 to 12 inches tall with fragrant yellow flowers. Flowers occur 3 to 7 per stem.
- Tulipa tarda (syn: T. urumiensis) flowers are yellow with white tips. Plants grow 4 to 6 inches tall. This tulip is easy to grow.
- Tulipa turkestanica has cream-colored flowers occurring 3 to 5 per stem. Flowers appear in early spring. Plants grow 5 to 8 inches tall. Hardy in zones 5 to 8.
Multi-flowering tulips (sometimes listed as Division 16) are actually members of one of the other 15 divisions. However, they are often grouped together in catalogs and on web pages. Multi-flowering tulips produce 3 to 7 blooms per stem. The main stem of multi-flowering tulips branches into secondary stems. Each secondary stem produces a flower. The flower on the main stem is slightly larger than those on the secondary stems. Bloom time is cultivar specific.