I have started my seedlings in a greenhouse since 1979 and under lights in the basement for seven years prior to that.
Seedlings started in the basement were kept at or near 70 F both day and night, germination was only fair. Temperatures in the greenhouse during the 1979 season were kept at 60 F at night and 70 F during the day. Under these conditions the seed from crosses of early blooming parents started to come up after two weeks and were fairly well up after three weeks. Germination was very good. The mid-season crosses also came up very well, but seed from crosses of late blooming parents came up very poorly. Two flats were so poor that I placed them in a cool spot for three weeks. This treatment resulted in the modest seedling production.
During the 1980 season I kept the greenhouse at 50 F nights, and 60 F days for four weeks. After four weeks there were a few seedlings coming up. At this time, for one week, I put the temperatures up by 5 F. Then the following week I raised them by another 5 F. Thus, by the seventh week after planting the seed I had the temperature up to 60 F nights and 70 F days. After this treatment, the seed of late blooming parents came up very well. However, seed of early blooming parents came up only fair. On this basis, it looks like one should divide the seed of early blooming parents and late blooming parents, where possible, and give them different treatments.
It is my feeling that one should provide conditions before planting that approach those which the lilies have been growing in under natural conditions for many thousand of years. I am sure that the lily seed, as do most other seeds, have a dormant period provided in its nature, so that the seed does not germinate in the fall. The seedlings would not have enough time to grow to a degree of maturity that would allow them to endure the oncoming winter.
Even in cereal grains it is necessary to have a certain degree of dormancy so that the grain, after becoming ripe, does not germinate in the stand or in swath, should there be a long wet period before grain can be harvested. I know that when germination tests of grains are made in the fall or early winter, the grain must be frozen for a week or two before the seed is planted to get a more true germination test. This freezing is not necessary in late winter or spring because the grain has already gone through natural freezing temperatures over winter.
I do not think that one should try to breed and select lilies with little or no dormancy in the seed. In the fall of 1979 I had two crosses in which there were 1 to 5 germinated seeds in the green pods. I planted these seedlings, but the growth is very slow, even through I had them under lights all winter.
To break dormancy, I left the seed outdoors for a month in a shady place, packaged in plastic to prevent absorption of moisture. This subjected the seeds to a daytime and night time change in temperature. Next, the seeds were placed in the freezer. Then, about 6-8 weeks before planting, I removed the seeds from the freezer and set them in the house. The seed was planted in a good soft, black soil, high in natural fiber, in early January. The soil must be fairly moist before working down into a fine powder and filling into the flats. This is necessary so that very little watering will be needed after planting. If the soil is dry at planting, not only will planting be very difficult, but the seed may start to float when being watered. Also, a large amount of water is needed to moisten the soil and the soil will become compacted. I am not in favour of putting flats in water and letting them absorb water. The soil gets much too wet before the moisture reaches the surface.
I plant my seed about 1/4 inch deep in rows two inches apart. This makes it possible to cut each row apart when planting to the field. Also, each row is marked with a label. After planting the seed and before watering, I put about 1/4 to 3/8" of vermiculite over the soil. This helps to prevent splashing and washing the seed out of the soil. The vermiculite also helps to keep the water from running to the lower spots or sides of the flats. Thus, getting a more uniform penetration of water into the soil. Because the vermiculite covers the soil, the water does not run sideways. This creates downward pressure into the soil. This way one can get more water to go into the soil faster and deeper, thereby needing to water less often. The vermiculite also acts as a mulch by keeping the sun off the soil and cutting down the loss of moisture by evaporation. Before I used vermiculite as a mulch, I found that I was over-watering my seedlings - because the top inch of soil dried very fast - thereby causing root rot. Also, I make sure to add more vermiculite as time goes by when bare spots of soil appear.
In past years I had been using formaldehyde to sterilize the soil before planting seed. But I have found the formaldehyde to be very hard on my lungs. This year I used "No Damp" (oxine benzoate 2.5%) made by Plant Products, Ltd., Bramalea Ontario. I found this product to be very good. It can be used as a soil drench before planting, after seeding, and after the seedlings are up.
I feed with a 15-30-15 fertilizer in late March and late April. I feel that the higher phosphorus should increase root development and potash should increase the bulb size of the seedling.
After the seedlings are up I give them a 15 hour day consisting of a combination of sunlight and fluorescent lights up to early April, the 24 hour days from early April to mid-May. This is done with a combination of daylight and cool white fluorescent lights. Not having enough lights for all my flats, I have to change the slow growing flats with the fast growing ones. One could see a great improvement in growth after the slow growing flats were placed under the lights for two weeks. I hang lights down nearly touching the leaves to keep the seedlings from growing spindly. This year they were large enough to start to plant out by late May. I had a visitor from Holland on June 1, 1980, and he remarked that he had never seen such nice seedlings.
My reason for not planting lily seeds in the late fall or early winter is that from November to February our days are very short and the sunlight is very weak. Our shortest days are only seven hours and 20 minutes long. Because of this, I would need to use lights all day. By December the leaves on these lilies died off. After I put them under lights they send up new leaves again.
Also, I found that with the cooler temperatures this year, I had very few small late germinating seedlings, whereas last year there were many such seedlings.
It is my feeling that the type of soil or medium is not nearly as important as is watering and temperature control. I also cover the flats with plastic until germination is well underway do as to insure an even moisture supply. Once the seedlings are growing, I water the flats once every four to seven days, and only after the soil becomes fairly dry. When watering I use four to five quarts per 18" by 24" flat with 3.5" soil depth. In six to eight weeks one may find worm damage to seedlings. This can happen even if adult worms were killed, as eggs in the soil may hatch. I used one tablespoon of liquid Diazinon per gallon of water and drench the soil.
The growing of lilies from seed is a challenge and one has to be ever aware of growing conditions if good stands of seedlings are to result from prized crosses.
by Fred Fellner (CPLS Newsletter #25:3-6)