Growing Lilies from Seed
Most lily species are quite easy to raise from seed. With most, you don’t need to use a glasshouse. The only “special equipment” needed is patience: though with special care a few species will flower in their first year from sowing, most take two or three years – a few even take up to seven. See ‘Lilies to Start With’ below.
Where to Get Seed
The best UK source of lily seed is undoubtedly the RHS Lily Group itself. It distributes seed to its members in late winter, at a nominal cost per packet. The Group’s annual list typically includes between 150 and 170 species or varieties and selections of species, and another 150 or so lily hybrids (as well as many non-lily species likely to appeal to lily lovers.) Link to most recent list.
Commercial sources which are able to supply a limited range of seeds of lily species and hybrids can easily be found with an internet search.
Lilies to Start With
Lilium regale is particularly easy to grow from seed, and is one of the most lovely lilies, full of fragrance. Lilium amabile, L. cernuum and L. pumilum, all rather smaller, flower quite quickly from seed – particularly if you leave them in their seed pots. Scented L. sargentiae will flower in its seed pot, somewhat stunted, in its second year, then grows into a splendid plant when planted out. If you have a heated greenhouse, you should be able to get L. formosanum and L. longiflorum – also very fragrant – to flower within their first year.
Seed firms often offer Mixed Aurelian Hybrids and Mixed Asiatic Hybrids. Starting to flower in two or three years, these give a fine range of colours, and are lime-tolerant and easy to grow.
When To Sow
Different lily species germinate in varying ways, and vary in the way that changing temperatures trigger them into growth. This has led some lily growers to develop quite elaborate techniques to speed germination and seed growth, such as putting the seeds into plastic bags of moistened vermiculite, keeping them warm for a few weeks, then refrigerating them for a few weeks more, then bringing them back into warmth.
In practice, you can get good results simply by sowing the seeds as soon as you get them, and – at least in temperate climates such as most of the UK – letting the natural change of seasons do all the work of triggering germination. However, the North American species and hybrids appear to do best when sown in early autumn to give them a period of cool night temperatures essential to their germination. Their first leaves will then appear in late winter or early spring.
Containers and compost
A 125 mm (5 in) plastic pot is probably the best size for ten or so lily seeds. Some growers prefer a 150 cm (6 in) pot, which has the obvious advantage of giving the seedlings more growing space and therefore more time to strengthen before the disturbance of transplanting. If you prefer clay pots, use them instead – it’s simply a matter of what you’re used to.
Over-watering is the most important thing to avoid.
The essential for lily compost is good drainage, which means an open texture. Most lilies prefer a neutral or slightly acid compost, so to be on the safe side it is best to base your lily seed compost on an ericaceous or lime-free mix. Lily growers soon develop their own favourite mix. One which has proved successful for a wide range of species is: one part gritty lime-free garden soil, one part coarse lime-free grit, one part fine composted pine bark
A simple alternative is half ericaceous mix, half coarse lime-free grit. A smaller proportion of grit may be better in well-drained clay pots.
Even the few species which prefer some lime in their soil, such as L. amabile, L. bulbiferum, L. candidum, L. chalcedonicum, L. henryi, L. pomponium and L. pyrenaicum, are all suited by these lime-free seed composts.
Sowing the seed
First place a layer of broken crocks in the bottom of the pot.
Then cover with a layer of coarse grit.
Fill the pot with compost to the internal level mark and firm lightly.
Sow the seeds separately on top of this compost. About ten seeds is right for a pot of this size, denser sowing can result in the seedlings being too close making damping off problems more likely. Viable seeds will have an embryo visible as a thin line when held up to the light.
Most lily seed is large enough that it can be sown on edge with the embryo downwards and this is the best method provided that care is taken not to damage it. Try to space the ten or so seeds equally.
If you have lots of seed of one species either use several pots, a deep tray (not a normal seed tray which is not suitable for lilies) or even sow them in a row in the garden or under cover.
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.
This will ensure that the seeds are safe and consistently moist until germination. The pots, inside their bags are best stored in a shed or garage and checked regularly.
Pots containing seeds of a tender species such as L. primulinum and L. neilgherrense are best kept in the shade in a cool conservatory or similar place with a minimum temperature of about 10c.
Germination and After Care
Some lilies produce an onion-like seed leaf upon germination. This is known as epigeal germination and may occur after a few weeks in lilies such as L. regale or be delayed as in L. carniolicum.
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.
Link to Table Germination Types
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.
All photographs are copyright © of Mel Herbert.