TULIPS AND THEIR CARE
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
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
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
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.
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.
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
(U.S.D.A. Hardiness Zone 6/7)
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.
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.