BULBS STORAGE FACTORS

Pest Control for Unplanted Flower Bulbs. Normally, flower bulbs do not have to be treated with fungicides or insecticides before being planted. Prior to using any pesticides, forcers must properly identify the specific pest to be controlled and be certain that only EPA approved fungicides or insecticides are used. For additional assistance, contact your local extension office or state floricultural entomologist or plant pathologist.

Relative Humidity in Storage Rooms for Unplanted Flower Bulbs. The relative humidity in storage rooms for unplanted bulbs varies with the ventilation requirements for the bulbs. When the bulbs require ventilation, the relative humidity should be maintained in the 85 to 90% range. Adequate ventilation and air movement must also be provided. A symptom of excessively high relative humidity and/or poor ventilation is the development of Penicillium on the surface of the bulbs. For other bulbs and roots, e.g., Astilbe and Dahlia, the relative humidity must be 98 to 100%. This is required to prevent drying of the bulbs.

Ethylene. Spring flowering bulbs must not be exposed to ethylene. This can result in aborted flowers and other disorders. Sources of ethylene include many ripening fruits and vegetables and combustible engines. Also, Fusarium infected tulip bulbs produce ethylene. Thus, tulip bulbs must be inspected immediately on arrival and all diseased bulbs removed from the trays. If greater than 10% of the tulips are infected with Fusarium, forcers should contact supplier immediately!

Major Factors for Preparing Planting Media for Bulbs.

1. The planting medium must be well drained! Yet, it must retain sufficient moisture for optimal plant growth. In addition, it should be as light in weight as possible, but heavy enough to anchor the bulbs. It must not compact readily because the bulbs and roots need oxygen as well as moisture. Thus, pure sand, pure peat, and heavy clay are not suitable planting media. Loamy soils, when mixed with amendments, e.g., peat, perlite, vermiculite or calcined clays, are ideal planting media for most bulbs . Generally, these are mixed in a ratio of one part soil, one part peat and one part coarse aggregate. When soil is used, be certain it does not contain harmful pesticide or herbicide residues.
2. The medium must be sterile!
3. For most flower bulbs, the planting medium should have a pH between 6 and 7.
4. The soluble salts level must be low.
5. The medium must be moist when the bulbs are planted.
6. At planting time, the temperature of the medium should approximate that of the bulbs, i.e., between 50 to 63 F. Thus, after sterilization, the medium must be cooled before planting the bulbs.
7. For some flower bulbs, e.g., freesias, Dutch Iris, and lilies, the media should be fluoride free. Thus, superphosphate should not be used. The pH should be near 7.