Texas Cooperative Extension,
Texas A&M University, College Station, Texas

January-February 2005

Questions About Bulbs

by The Netherlands Bulb Council

Narcissus 'Grand Primo'
Narcissus 'Grand Primo'

Q. Why donít flower bulbs in the ground freeze in the winter?

A. Bulbs are designed by nature to withstand cold winter temperatures. Indeed they rely on winterís cold to trigger the biochemical process necessary to bring the bulb to flower in spring. While winter soil may actually freeze to depths beyond which the bulbs are planted, soil temperature will rarely fall below 29į F or 30į F. At these just-below-freezing temperatures, water in the cells of the bulb may freeze but the cells will not be harmed. Also, as is true for many hardy plants, cold temperatures trigger starches in bulbs to break down into glucose and other small molecules. This simple sugar or glucose, interacting with other small molecules, acts in much the same way as salt on a winter sidewalk. The sugar in the bulb, like the salt on the sidewalk, lowers the temperature at which water freezes. This fortunate chemistry helps to keep bulbs safe and snug in their winter beds. Other factors that help keep soil temperatures within tolerable limits include an insulating snow cover and, in colder areas, a nice layer of mulch over the bulb bed once the ground temperatures have dropped.

Q. What if itís already early winter and I still havenít planted my bulbs?

A. When best plans fail and you still havenít planted your bulbs by early winter, the answer is - just plant the bulbs as soon as you can, even if you have to chip into the ground. Bulbs are not dormant, theyíre alive - and they wonít last much longer if left unplanted. If you can get them into the ground (either in pots or in the garden), chances are good that theyíll grow. If you donít plant them soon, you may as well toss them out.

Bulbs that get less than 10 to 14 weeks (depending on their type) of sustained cold temperatures still come up but may be shorter than usual. If they are types or varieties that perennialize or naturalize, theyíll come back normally in future years if their foliage is left to die back after bloom in spring.

Expert gardeners have one more late season trick up their sleeve: they pot up unplanted bulbs for indoor forcing, or as container plants. With containers, you have the advantage of being able to control the initial soil temperature by adding your own soil. Choose the light potting soil mixes sold at all garden retailers. Move small containers to an unheated garage or other cool, yet protected place. In spring, use the potted bulbs as accent plants or bring them indoors. Remember these are last ditch measures. Once the time for fall planting has arrived in your area, the sooner bulbs are safely in the ground, the better.

Q. What is the difference between a daffodil and a narcissus?

A. The simple answer is: none. Narcissus is the Latin or botanical name for all daffodils, just as Ilex is for hollies. Daffodil is the common name for all members of the genus Narcissus, and its use is recommended by the American Daffodil Society at all times other than in scientific writing.

Q. What is a jonquil?

A. In the southeastern U.S., all yellow daffodils have traditionally been referred to as jonquils. However, according to the official book of daffodils, the International Registry and Daffodil List, maintained by Great Britainís Royal Horticultural Society, only certain daffs can truly be called jonquils. These have several yellow flowers, strong fragrance, and rounded foliage, as defined under Division 7 and Division 10 in the official registry. However, here in the South, should a gardener ask to show you his or her jonquils, it is recommended that you allow good manners to triumph over erudition. Admire the flowers and enjoy the sweet tea.

Q. When is the best time to plant tulips, daffodils and most other bulbs in fall?

A. In most areas, the "window" of time for planting bulbs in fall is fairly wide. Here is a practical way to plan:

Time to start planting bulbs: once night-time temperatures drop into the low 50s or 40s for two weeks.

Time to finish up: once hard frosts are coming. Generally bulbs root best in the period six weeks or more prior to the ground freezing.

After planting bulbs: water the site well. Typically fall rains will take over this task for the balance of the season. For more information on fall planting see www.bulb.com (The Netherlands Flower Bulb Center) US Bulb Planting Regions, When to Plant Bulbs Where You Live.

This article appeared in Horticulture Update - January-February 2005, edited by Dr. William C. Welch, and produced by Extension Horticulture, Texas Agricultural Extension Service, The Texas A&M University System, College Station, Texas.

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