HO-35
TULIPS AND THEIR CARE
ISSUED: 9-74
REVISED: 8-84
Bob Anderson, Extension Horticulturist

Tulips are an important part of the spring landscape in Kentucky. Few plants grown in the home landscape add as much color and interest on the warmer spring days of April and early May. Tulips can produce nearly all colors to satisfy the tastes of any home gardener.
Over a hundred different cultivars of tulips are available for fall planting. The different types and the many colors can be purchased from mail order bulb companies, garden centers, supermarkets or department stores. With careful selection, tulips can be picked to flower in succession from April 1 to May 15 in the garden. Some types naturalize reasonably well in Kentucky so they can be a permanent addition to the landscape.
Trials at the UK College of Agriculture's Landscape Garden Center focused on the naturalization of tulips and other spring flowering bulbs. Bulbs planted in various sites and given different types of care have been observed for four years. Over 50 cultivars have been included in this study which was supported in part by the Netherlands Flowerbulb Institute, Inc. The recommendations for the care and lists of tulips included here are based on these trials and the Holland Bulb Garden Guide.

Planting Site
Well-drained sites are essential to tulip culture. Established gardens and beds or newly cultivated areas are fine as long as no triazine herbicides (e.g., simazine) have been used on the soil. The soil pH should be 6.0 to 7.0. Tulip bulbs will not do well in heavy clay soils, so poor soils should be amended with compost, peat moss or other organic matter before planting. Tulips will do well in full sun or partial shade. Yet the perfect location does not receive full sunlight in the middle of the day. In this location, reduced water stress on hot spring days will extend flower life and allow the bulbs to mature properly after flowering. Generally, tulips should not be planted directly in the lawn. They perform better and are easier to maintain when grown in mulched beds.
Tulips can be used as annuals or perennials as a mass display in beds, as accent spots in ground cover beds, in rock gardens or under trees and near shrubs. They should be planted in groups rather than individually so the mass of color increases visibility. Smaller tulip bulbs should be planted in groups of ten to twelve while the typically larger bulbs of most types can be planted with as few as five to six bulbs in a group. Types that flower at different times can be interplanted in the same site. If you desire perennialization or naturalization of the tulips, avoid planting near heated basements.

Fall Planting Techniques
Plan to plant tulip bulbs between October 1 and Thanksgiving. Start by cultivating and cleaning the bulb planting site. Small sized bulbs (about 1 inch) should be planted 1 to 4 inches apart in holes 5 inches deep. Large bulbs (2 inches or more) should be planted 4 to 8 inches apart in holes 8 inches deep. These planting depths will help protect the bulbs from frost, animals and physical damage due to hoeing.
Thoroughly loosen the soil under the bulbs and mix in one handful (1 ounce) of bonemeal per square foot. Place the bulbs upright in the hole (pointed side up) and cover bulbs with half of the soil removed from the hole. Water the bulbs thoroughly and replace the remaining soil. Fertilize the soil surface with 10-10-10 (N-P-K) at a rate of 3 to 4 pounds per 100 square feet, or apply a sulfur coated slow release fertilizer at a rate of one rounded tablespoon per square foot in the bottom of the hole with the bonemeal. Cover the bed with 2 to 3 inches of organic mulch and water thoroughly again. If the fall weather is dry, water the area as needed.

Spring Care
As soon as the plants emerge in the spring, fertilize the area with 10-10-10 (N-P-K) fertilizer at a rate of 1 to 2 pounds per 100 square feet. After the flower petals fade or fall off. remove the flower organs with scissors or a knife. Allow the remaining foliage to die naturally. Bulbs will not mature properly when the foliage is removed prematurely. When tulips are planted directly in the lawn, the foliage generally cannot be removed when the grass is first ready to mow. This can create an unsightly area and a maintenance nuisance.
Splitting or harvesting bulbs is generally not advised, yet many home gardeners have been successful with these procedures for years. If the bulbs flowered satisfactorily in the spring, do not disturb them. If they need to be moved, dig them when the foliage has yellowed and died. Store the bulbs in a relatively dry and ventilated location until fall planting time.

Bulb Selection
Be sure to select bulbs that are firm at the time of purchase. Check and discard any with rot on the basal plate. Small nicks and loose skins do not affect the development of the bulb.
Tulips offer variations in flower color, flower form, plant height and the time of flowering. Personal tastes and the garden design will dictate which tulips to select. The various types of tulips and their peak flowering dates in Lexington are listed in the following section. Expect peak flowering up to one week earlier in southern Kentucky (Pikeville, Corbin, Bowling Green, Paducah) and up to one week later in northern Kentucky. It is not possible to list tulip cultivars that will definitely flower for Derby Day (the first Saturday of May). Spring weather is quite variable; many tulips missed Derby Day two of the last four years. A mixture of Darwin Hybrid and Single Late tulips should spread flowering over sufficient time to include Derby Day, regardless of the weather.
The conditions to assure naturalization or perennialization of tulips have not been identified. Generally, all tulips are excellent the first and second year when planted properly. In trials at the Landscape Garden Center, many tulip cultivars doubled or nearly tripled the flower number in the second year. By the third and fourth year, tulip flower number decreased for most cultivars depending on the garden and weather conditions. Yet some gardeners in Kentucky have had tulips completely naturalized in their landscape for many years. The cultivars that naturalized best in our trials are noted in the listings that follow.

Types of Tulips and Their Peak Flowering Times
Lexington, Kentucky
(U.S.D.A. Hardiness Zone 6/7)
 
Kaufmaniana Tulips  Fosteriana Tulips
Greigii Tulips Triumph Tulips
Darwin Hybrid Single Early
Double Early  Parrot
Lily Flowered Single Late
Double Late

This classification of tulip types is based on information in Classified List and International Register of Tulip Names, 1982. Koninklijke Algeineene Vereniging voor Bloembollencultuur, Hillegom, The Netherlands. Additional and smaller classes of tulips such as Fringed, Vridiflora, Rembrandt, and miscellaneous species are not included in this list because representative cultivars of these classes were not included in our trials.

Selected References
All About Bulbs. 1993. Ortho Books, San Francisco, CA.
DeHertogh, A.A. 1982. Holland Bulb Garden Guide. International Flower-Bulb Center, P.O. Box 172, 2180 A.D., Hillegom, Holland.
Handbook on Bulbs. 1981. Brooklyn Botanic Garden, Brooklyn, NY.