LILIES can be propagated from seed or vegetatively.
Propagation from seed
Lilies grown from seed rarely pass on virus diseases present in their parents and are often more vigorous. Growing from seed means all offspring are individuals and are all slightly different. With species this difference is only rarely significant but with hybrids the differences can be quite marked unless the hybrids have been inbred within the type for a number of generations. It is probably better to grow most species from seed where possible and hybrids were some variation is not a problem. Some forms of Lily species that have been cultivated for some time may have lost the ability to produce seed. Most of the Lilium candidum and L. tigrinum forms available are incapable of producing seed.
Seed germination is often described as being of four types. Epigeal Immediate, Epigeal Delayed, Hypogeal Immediate and Hypogeal Delayed. In the real World, it is not quite so straightforward - however, it is a guide (!).
With Epigeal Germination when the seed germinates - the roots and future bulb grow downwards and the bit nearest the seed elongates grows upwards and turns green, often dragging the seed itself up with it. This first leaf looks rather onion like - there is only one - and it the reason why lilies are classed as “Monocotyledons” - with grasses, bamboo’s, orchids and bananas- they only produce one (mono-) seed leaf (cotyledon).
With Hypogeal Germination the plant grows downwards, the seed leaf does not elongate or grow upwards and so is never normally seen. The first leaf normally seen on a hypogeal germinating seed is the first true juvenile leaf, and this is usually broadly lanceolate in shape.
The “Immediate” and “Delayed” part of the germination refers to the time it takes to produce the first leaf. Immediate germinators are those which planted in warm moist soil will grow in a few weeks - usually 2-3 weeks. Delayed germination is generally caused by special needs of the plant. Delayed germination is seen in seed produced by species which in the wild are subject to unfavorable growing conditions during part of the year. Delayed germinators tend to need two or more quite different temperatures to get the seed to produce its first visible leaf.
Lilies grown from seed produce three types of leaf, one cotyledon leaf, several juvenile leaves ( the true leaves), and the adult leaves.
The cotyledon leaf usually develops rather grass or onion like in epigeal germinators. In Hypogeal germinators the seed leaf normally never develops above ground and therefore rarely even turns green.
Juvenile leaves emerge from the bulb and usually in a rosette. The leaves are usually quite broad and are attached by the leaf stalk directly to the bulb. Juvenile leaves are often much broader than the adult leaves. L. candidum produces juvenile leaves in the winter even on large flowering plants. Juvenile leaves are normally only produced by young /small non flowering bulbs. Juvenile leaves are more efficient in turning light energy into bulb weight. Juvenile leaves are also more persistent than adult leaves, they are very reluctant to senesce in the Autumn.
Adult leaves are attached to the stem. Flowering sized bulbs generally only have adult leaves. Adult leaves are believed to have generated from adapted bracts ( the protective covering found around most flowers while they are developing). By producing adult leaves radiating from the stem it gives the plant a competitive advantage over other bulbs in an environment with other ground covering plants. Adult leaves are generally not as efficient in turning light energy into bulb weight
The reason for the germination differences is generally a protective device in the wild- they do not want to stick their heads up in the middle of a Siberian Winter or in the middle of a summer drought. Epigeal Immediate lilies tend to come from areas with mild winters, Hypogeal delayed species tend to come from areas with severe winters. However there appear to be intermediary forms within species found at different sites. Lilium martagon a specie with the widest natural distribution from England through Europe to Siberia has hypogeal delayed germination. However because of the different forms originating from milder winter areas some have hypogeal immediate germination. In cultivation there is a tendency for lilies to loose delayed germination, as the human hand will tend to favour quick germinators, and these in turn will tend to be used more for breeding. It is likely therefore that many of the hybrids will increasingly become immediate germinators over the years.
general requirements for germination
an open compost which never waterlogs or dries out is ideal. It is probably better to use an acidic or ericaceous compost for most lilies. The compost should have a low salinity (one which has not too much fertiliser). For germination like with most other plants, phosphate is required but only low levels of nitrogen and potassium. I still prefer a peat based compost to soil based because during transplanting the small seedlings have less root disturbance. Peat also may have traces of natural antibiotics.
Lily seed does not appear to need light for germination so deeper planting or incubating initially in the dark is an option, remembering that the seedlings will need light as soon as they germinate.
It was/is common practice to germinate lily seed in frames outdoors, sowing the seed when fresh and just waiting for germination, however long it takes. My preference is to sow fresh seed at “the best” time in trays. The germination process should be faster and the resulting seedlings germinate at the right time, allowing the plants to develop quicker. Apart from getting a bigger plant quicker, it also has the advantage that the lily has had less chance of picking up virus diseases. By growing by this method most of our hybrid lilies flower in the second year
Methods for germination
We 3/4 fill the trays with compost and water till it drains. We sometimes add a fungicide to the water. Leave to drain. After adding the water, the compost has invariably sunk a bit. We normally broadcast our seed up to 1000 seeds per standard UK seed tray. (About 14”x9”) if the stock is particularly valuable or short supply we only sprinkle in up to about 250 seeds. Sowing thickly saves compost and in the energy needed to incubate the trays of lilies. We then sprinkle damp compost over the seeds to the top of the tray without firming. This damp compost tends to soak up surplus water. The downside of sowing thickly is the increased risk of damping off diseases. However transplanting the seedlings as soon as they start to produce leaf reduces this problem.
Lower sowing densities are therefore probably more practical for home produced plants. With epigeal germinating lilies, you can place each seed on edge rather than broadcast. Some claim that you can better germination. The author has no experience of this.
Hypogeal Germinators We generally sow hypogeal delayed seed as soon as ripe in the Autumn. We slide the trays into thin polythene bags and close them. This prevents moisture loss but allows a limited movement of oxygen through the film. We then incubate them at 21C for about 12 weeks this stimulates the temperatures expected the first summer after sowing. We then store them at 5C for about six weeks - to stimulate the following winter. They then go onto the bench in an unheated glasshouse in early spring and are taken out of the polythene bags, they start producing leaves with a few weeks. This generally works well for Oriental Hybrids and L speciosum and L. canadense Most of our experience has been with auratum/speciosum crosses. Cardiocrinum giganteum. L. auratum, L japonicum and L. rubellum do respond but we only get a percentage to develop. Our stocks of L martagon come into leaf during the first warm period and so we will treat them as hypogeal immediate. We are also finding a percentage of the oriental hybrids are also coming into leaf during the first warm period. We have very little experience of West Coast Lilies the few we got to germinate mainly damped off. It is possible that they mainly prefer “lower” high temperatures for germination to stimulate autumn or spring conditions rather than summer conditions. Cardiocrinum may have double dormancy i.e. it may need warm-cold-warm-cold temperatures to stimulate two summers and winters.
Epigeal immediate/Epigeal Delayed and Hypogeal immediate seed is probably best sown in early Spring so that the leaves come up with the improving light. January or February is ideal sowing time, February -March if no heat is available. Alternatively, the seeds can be incubated in the house for about 7-10 days and then put in the greenhouse. We do not normally heat our actual glasshouse, unless the temperature drops below about 28F (-1.5C) but we do use bottom heat on the glasshouse bench. A temperature of 21C at the base of the seed tray hastens germination of most lilies. L pumilum generally start producing leaves within 2 weeks, though most do not show green until about three weeks. Asiatic Hybrids, The Hybrid Trumpet lilies L. longiflorum, and L. formosanum and regale germinate quite quickly. L henryi and some of the wider opening trumpet lilies often germinate over several weeks. Some L. martagon forms and L. nobillissimum are hypogeal immediate. Generally older seed tends to be slower germinating and in borderline plants there appears to be an increasingly amount of spread of germination.
If growing in a peat compost transplanting the young seedlings into small pots as soon as possible seems to work well