When all the seeds are in place, top the pot with about 1cm thickness of the same compost mix and firm gently. If you plan to leave the pots outside then it may be better to top with grit rather than compost as this will protect the seeds from being washed out of the compost by heavy rain.
Put in a label with the name of the lily and any other information you think relevant, the date and the number of seeds for example. After sowing place the pot in a bowl of water and allow the water to soak the compost by capillary action.
Let the pot drain and then either put it out of doors, in a shady spot (some people like to cover the pots with a cloche or cold frame, as protection against very wet weather, slugs, and scratching birds and animals) or seal it, using a twist tie, in a clear plastic freezer bag.
Others including L. martagon and most North American lilies such as L. pardalinum develop below ground initially, not showing a leaf until the following spring. This kind is known as hypogeal germination. A few species exhibit other kinds of germination. It is very helpful to know which kind of germination to expect as it will guide the grower as to when seed pot checking will be most appropriate.Once the seedlings are visible remove the bag if you have used this method and then move the pot to a suitable growing position. Try to keep the pot just nicely moist, and cool in hot weather. If you can keep the seedlings growing into winter for their first year (in a heated greenhouse), they will establish much more quickly.
Essential rule: don’t let the compost get soggy – avoid over-watering! Liquid feeding speeds growth, but without feeding you may get an even better root system, and plants that are more resistant to disease.
Keep a close eye out for greenfly, which love tender young lily leaves – as do slugs and snails.
Keep the young lilies in their seed pot until they are a good size (say two years). Then pot in a similar compost with a slow-release fertiliser, or plant out in well-drained soil or a raised bed. This is often done after foliage has died down but the young plants can be successfully moved on whilst in growth if great care is exercised.
Don’t abandon a bare seed pot until after at least three years, as some lilies can delay germination until they have been through several seasonal cycles.