Lily Group Seed, a Great Resource by Alisdair Aird
The Lily Group's Seed Distribution has been a real treasure trove for me, over the years. I was originally prompted to join the Group by its displays of flowering lilies at Vincent Square, in the late 1970s. What particularly attracted me in those displays was the charm and elegance of so many of the species. Very few of those species were available commercially, let alone at reasonable prices.
By contrast, the Group's seed distribution made all sorts of rarities available, with the bonus that any seed-raised plants would at least initially be virus-free. Once I realised that the only horticultural skill needed for raising lilies from seed is patience, I embarked on what has turned out to be an immensely enjoyable and rewarding voyage of discovery through Lilium's remarkable range of sizes, shapes, fragrances and colours. If you stick to species, producing seed yourself is relatively simple. People raising hybrids have to go to considerable lengths to ensure that their hoped-for cross is not contaminated by unwanted pollen - and even then may face great difficulties in securing viable embryos.
Not so with species. Some species are self-fertile, so that even a single plant will produce viable seed. With others, once a stigma has been pollinated with pollen from another plant of the same species, it is very unlikely to be receptive to pollen from a different species (beware that this is not the case with the various subspecies of Lilium pardalinum, which are quite promiscuous among each other - and I suspect that Lilium kelleyanum is all too happy to join them). I find it better to leave the pollen-coated stigma uncovered than to use the little foil caps used by hybridisers. But in a warm summer hoverflies, greedy for pollen, can be a nuisance with the later-flowering species.
Another useful point about growing lilies from seed is that, if the seed of a species has reached the Lily Group's Seed Distribution that means someone somewhere has been able to keep that species so happy that it has produced seed. So you know that you are dealing with possibilities. Until just a few years ago, all my lilies were seed-raised, and nothing but species. It's only recently, growing bulbs of the new species from China, that I've realised how helpful this "possibility" pointer of the seed distribution is. Certainly some of the new rarities from China seem perfectly easy to grow (and indeed now to raise from seed): notable examples are Lilium rosthornii, Lilium fargesii, Lilium lijiangense and the splendidly robust new plant, allied to Lilium taliense, that John Lykkegaard calls var. kaichen and that has appeared in the seed list as aff. taliense. But others (such as the bakerianum group) - I find them very difficult or impossible to grow.
Growing lilies from seed
Most lily species are quite easy to grow 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.
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 last list included 199 species or varieties and selections of species, and another 120 lily hybrids (as well as several hundred non-lily species likely to appeal to lily lovers.
The main commercial seed firms generally sell seed of one or two easy-to-grow lilies. Specialist seed selling companies such as Chiltern Seeds (www.chilternseeds.co.uk) and Rareplants (www.rareplants.de) (stock around two dozen different lily seeds, including hybrid cultivars as well as individual species.
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.
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. But this larger size needs more care to avoid over-watering, especially when the seedlings are very young. Over-watering is the most important thing to avoid.
If you prefer clay pots, use them instead - it's simply a matter of what you're used to.
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.
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
Fill the pot with compost to the internal level mark, and sow the seeds separately on top of this compost. A simple method with ten or fifteen seeds is to work clockwise round the pot a little way in from the rim, then dot the last few seeds around the centre. Some people score the top of the compost lightly, so that they can stand the flat seeds on edge - they claim this gives better results.
If you have lots of seed of one species, don't be tempted to sow them more thickly than this. This doesn't seem to increase the number of young plants you get from that size of pot. Instead, use a deep tray.
When all the seeds are in place, top the pot with a finger's thickness of coarse lime-free grit. Put in a label with the name of the lily, the date, and the number of seeds - it's always interesting to see later what proportion germinate, and grow on to be transplanted.
After sowing, water the pot well, and 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.
Only a few lily species are best sown in a greenhouse: L. formosanum, L. longiflorum, L. neilgherrense and L. philippinense.
Some lilies such as L. regale show an onion-like seed leaf about three weeks after sowing. Others including L. martagon and most North American lilies such as L. pardalinum develop only a root initially, not showing a leaf until the spring of their second year.
Once the seedlings are visible, try to keep the pot just barely 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 grow a stem (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. The best time to do this is after foliage has died down. You'll find that if you let the compost in the seed pot more or less dry out first, the young plants are easiest to separate when you gently tip them out. October is usually a good time for this.
Many North American lilies have very fragile bulbs: handle them delicately.
Don't abandon a bare seed pot until after at least three years, as some lilies can delay germination till they have been through several seasonal cycles.