After being programmed, forcers should be prepared to plant bulbs when they arrive. If they must be stored, place at 32-35° F. Forcers should always check to be certain the bulbs are not seriously damaged or diseased. Do not store for longer than 10 days. DO NOT REFREEZE!!
In all cases, the planting media should be sterile, well drained, have a pH of 6.5 to 7.5 with pH of 7.0 being preferred. Because some lilies can develop leaf scorch due to soil borne fluoride, the medium should not contain superphosphate or perlite. Dip for 30 minutes with one of the three following recommended formulas:
For potted plants, use standard pots and plant bulbs so there is 2 inches of planting medium above the bulb nose. This is necessary to develop stem roots.
Suggested Number of Bulbs Per Pot
12/14 cm. 3 per 6 inch (15 cm) pot
14/16 cm. 1-2 per 6 inch (15 cm) pot
16/18 cm. 1 per 6 inch (15 cm) pot
Lilies require a medium to high Light (>2500 ft candle) intensity greenhouse, especially during the short days of winter. If shading was used during the summer, be certain to clean the glass thoroughly before winter. In most instances lilies respond to HID lighting during the winter months. This aids in reducing flower abortion and abscission especially with sensitive cultivars. Forcers who have lowlight intensity winters should seriously consider installing an HID lighting system for forcing cut lilies. Use light 4-8 hours per day. When very high light conditions occur (spring/summer), screening or shading is advised.
Water the planting medium thoroughly after planting and then keep the medium moist, but not wet.
Growing in the Summertime
It is very important that the stem roots are developed before exposing the lilies to warm summer temperatures. Keep the planted bulbs for 3-4 weeks at or below 65°F to allow the roots to grow. This can be done in a bulb cooler or cool basement. Bulbs that have a poor root system will flower unevenly and have a lot of bloom dropping.
Use 55-63°F night temperatures and not higher than 70°F day temperatures. Avoid great fluctuations in temperature, because this can help to promote leaf scorch. Whenever possible, start Orientals at 59°F for about 4 weeks. Later, Orientals can be forced at higher temperatures (63-65°F) than Asiatics. In general, Asiatic and longiflorum lilies take 30-35 days to flower after they reach the visible bud stage of development and Orientals take 50-55 days. When seasonally warm temperatures occur, try to keep the soil and air temperatures below 68° F. Use shading when necessary.
Use a well ventilated greenhouse. Do not permit humidity to build up.
The bulbs themselves contain lots of stored food, and they should be able to support the plant until the shoot emerges. Recommendations suggest withholding fertilizer until the shoot is 4-6" tall. Some growers incorporate a 10-6-4 slow release fertilizer in the medium prior to planting. Suggested rate is eight pounds per cubic yard. Use a liquid fertilizer such as 16-4-12 at the rate of 200 ppm to help deepen foliage color. If a preplant fertilizer has been added to the soil, then just use the liquid fertilizer every two weeks. A well fertilized lily tends to be shorter than an under fertilized plant.
Plant Growth Retardants
Height control is one of the more difficult aspects of pot lily forcing. Forcers need to rely greatly on their past experiences with the various cultivars and then decide whether or not to use ancymidol (A'Rest), Bonzi, Sumagic, or any other approved growth retardant. If soil drenches are to be used, split applications are usually best. Also, the pH of the medium needs to be about 7.0 to get the most effective response of the soil drenches, particularly for A'Rest. The first to be applied at shoot emergence, the second 10-14 days later. Foliar sprays can also be used. In addition there has been research conducted on preplant bulb dips. If EPA approved, forcers should experiment with the procedure to determine the best rate and length of the bulb dip to use for their forcing conditions and cultivars used.
Marketing and Storage
Forcers - plants should be marketed as soon as first flower begins to color. This insures that the consumer will receive maximum enjoyment. Care must be taken not to damage the unopened buds during marketing. Storage should be kept to a minimum. If they must be stored, place them at 35-40°F when the first flower is fully colored, but not open.
According to Cornell University trials a 50 ppm application of facination 2 days before storage will prevent leaves from yellowing.