Breeding Your Own Lilies

Lilies are exciting plants. Their life cycles are dynamic; their flowers are normally spectacular, certainly always beautiful; and they can be grown in all types of garden. Many kinds are very easy and quick to raise from seed to flowering specimens. Your lilies could be blooming within a year. You do not need acres of space nor any special expertise; you hardly need to invest any money - just some time and interest.

Is it difficult?

Most species and hybrid lilies are fertile and give plenty of seed - from one pod, 20-100 seeds can be expected. Fresh seed germinates quickly, and seedlings of many popular kinds can be grown on to bloom in one or two years. The bulbs of particularly good lilies can be propagated rapidly. You will not find it difficult to place what you feel were 'also-ran' seedlings. Fanciers with only modest plots have bred lilies that have been named and sent all over the world, for their flowers to be enjoyed.

How to produce hybrid seeds

Almost all lilies produce an abundance of pollen on large easily detached anthers. Ideally, once you have chosen a flower as prospective seed parent, you should remove its anthers before the pollen has been shed, perhaps already on the stigma. Fingers will do this job, but a pair of tweezers is helpful - holding the anther(s) with a pair of tweezers is easier and keeps your hands clean. If you are ultra-cautious, you could protect the stigma with a little contraceptive cap made out of a twist of foil or sticky tape. However, the stigma becomes sticky and receptive soon after the flower has opened and this is the time to introduce the pollen from your male parent. You can bring an anther taken from this cultivar into contact with the stigma so that pollen is plastered evenly over all three lobes.

After pollination some fanciers enclose the bloom in a paper bag or cover the stigma to prevent strange pollen, carried by wind or insect, from entering. It rarely matters. However, if you were dealing with a very rare kind extra caution maybe justified. Working with flowers other than lilies the familiar method to ply a stigma with pollen is to transfer it using a small watercolor brush. This is normally a pointless exercise with lilies. It is easier and more efficient to offer the anther directly to the stigma. If the pollen has been stored for some while, a small brush is a useful tool -too large a brush will waste pollen and is too clumsy.

Once a cross has been made, it is important to label the flower immediately. It is no good thinking you are going to remember what you have done - you can easily get confused with other crosses and flowers within a few minutes. You will need a tie-on label of card or plastic for it to survive for several weeks while the seedpod ripens. The parents should be noted on the label in indelible, waterproof pencil or ink. The convention is to write the parents in this manner: 'Enchantment' x 'Connecticut King', where the first name is the seed (female) parent and the second the pollen (male) parent.

Should you plan to mate two flowers that are not in bloom at the same time, there are two approaches: you can artificially change the flowering time of one by retarding it or, more easily, bringing the later one into bloom earlier by gentle forcing. The alternative is to store pollen until such time as the female parent opens blooms. You can take anthers just before they have split and spilt their pollen. Place them in a plastic pill box and leave them in a safe, warm, dry spot until the anthers have split and dried out. Label the container with the cultivar name - one lot of pollen looks much like another - and only clamp the container lid on when the anther is dried and the pollen free. Now keep the container in a domestic refrigerator until such time as the pollen is needed.

This procedure suffices when the pollen is only to be stored for a few days. If you need to keep it for several weeks or even months, you will need to take a little more care to ensure that it is kept dry and will not become mouldy. You can easily do this by enclosing with it in the container a deliquescent chemical or manufactured gel that will absorb the small amount of moisture that may be present. Calcium chloride is one such chemical. Place a small amount in the bottom of the container, cover it with gauze or cotton wool and then store the pollen on top of a small piece of blotting or tissue paper. Such an arrangement can keep pollen vital for half a year in the refrigerator.

Harvesting seeds

Hopefully the cross proves fertile, the seedpod swells and becomes upright. Infertile ones remain small and shrivel. As the seeds mature and begin to ripen, the seedpod starts to dry out and may begin to split at the top prior to allowing the ripe seed to escape. At this stage you need to either harvest the complete pod or to make sure that no seed escapes. You can take the pods away, complete with their label, and lay them on clean paper in a dry, airy spot where the seed will be safe and the final ripening can take place. Alternatively you could place a square of muslin or fine-mesh plastic net over the pod and secure it with a small rubber band to prevent any seed falling. If you are away for a few days or have no time to check the ripening pods regularly you will at least know that all is safe and that your earlier work was not in vain.

Later-ripening pods may well have to be cut off towards the end of autumn when they will not ripen any further. Hang such pods upside down over paper in a warmer, dry spot so ripening can continue and ripe seed can be safely gathered. It is a sensible precaution to spray developing pods with fungicide in the autumn to prevent infection and destruction. Again, be careful to label all batches of seed very carefully at all times.

Why breed lilies

Raising flowers with new or improved colors or combinations of colors is the obvious first aim. Larger flowers or wider-petalled ones may be desired. It could well be that more blooms to a head or, perhaps more importantly, their more pleasing disposition is a top priority. Serious growers may well put disease-resistance at the top of their particular list of criteria -  health is certainly something all fanciers should bear in mind.

Other aims could be to extend the flowering period of a particular group of flowers - later Martagons, earlier Orientals for example. Breeding cultivars that last a week or more longer would be a very big bonus. Most, but not all Asiatics, are without scent - something the newcomer to lily - breeding is quick to want to change. While many species have little perfume, this does not invalidate the idea that a range of good garden Asiatics with pleasing perfumes would be welcomed by everyone. Commercial breeders have welcomed Orientals with less perfume in the belief that flowers with extrovert scents are not so much in demand as less endowed ones.

Some short-stemmed lilies suitable for pots have already been bred but there is a huge need for a wider selection of flower colors and types. The preoccupation of many breeders with raising flowers suitable for the cut-flower trade has led to a plethora of upright-facing ones, a perfectly acceptable form but perhaps not a pose that encapsulates the essential grace of the genus. Graceful, semi-pendant poses are very appealing and seem right for lilies. There are so many elegant species and hybrids that opportunities beckon from all sides.

It could be worth jotting down your own aims. Once the flowers are out there is a big temptation to distribute pollen allover. You could find yourself with a huge harvest of seed, needing half a county to sow and rear the resulting plants. On the other hand, if you are trying more extreme crosses, the pods may shrivel up and you are left with nothing until the next season. A balance has to be struck so that you are working within your own resources of time, space and energy. Some fanciers pollinate a single bloom of one particular cross.

There are one or two guidelines that are worth following. First, as you are investing time and space, you might as well be sure that the cross you make is correct and no foreign pollen makes contact by wind or insect carrier. Remove anthers of the seed parents before they drop any pollen, and cover the stigma with a foil cap. Self-pollinate the best seedlings, or back-cross these to the parents. This ensures that you stand some chance of benefiting from recessively-governed factors. Raise as many seedlings as you practically can from a particular cross. Only thus can you get any idea of the genetic potential of the cross.

Selecting parents

Usually, the closer two lilies are related the more certain they are to mate easily. Some kinds are very fertile to their own pollen but many are fully or partially inhibited. When one of the parents is a plant of questionable fertility it is sensible to use this as the male parent, other things being equal. An ovary can hold only perhaps a hundred plus gametes as ovules but there can be many thousands of pollen grains, giving a higher chance of fertile gametes.

Crosses between widely-different types of lily may prove impossible or very close to this. However, it is the exceptional occasion which might give just the odd seed or two that could begin a new range of types. Crosses between species and hybrids belonging to different specific groups or hybrid divisions can take place, although one must not expect a high success rate and any pods harvested may well be full of chaff. Yet there could be the odd seed.

The barriers between the divisions seem to be tumbling all the time. Perhaps the most exciting series of crosses are those between the trumpet lilies and the Oriental lilies. They seem possessed of huge vigor; this strength with size and flower colors promises great things for our gardens. This series is currently called 'Orienpets' -not perhaps the prettiest of names. The other trumpets, those like L. longiflorum, are now also kicking over the traces, and a series of t. longiflorum x Asiatic hybrids is already on the market.

Fertility and infertility

There may be a number of reasons why certain crosses do not give seed. There could be a problem with the chromosome count. The problem could be a relatively simple one: the pollen parent may have pollen that has been genetically engineered to travel a certain distance down the parent style to the ovary, and this distance could be less than required for the chosen seed parent. The answer could be to complete the reverse cross which should give you the same genetic mix.

Alternatively, if we suspect that style length is the problem, we can resort to surgery and cut off a part of the style and introduce the pollen to the reduced style. You could cut to leave a 1cm (1/2in) length of style. You will of course not have the nice, wide stigma to plaster pollen on, but a lot of pollen grains can be massed on a very small area. Some breeders moisten the cut surface with the juices present on the ripe stigma surface; this may well help the pollen germinate quickly and get growing down to the ovary.

The wider the cross, the more disparate the parents, the greater the likelihood of problems for the pollen. Crosses between different divisions can prove difficult. At one time, crossing trumpet lilies with Orientals would have been thought impossible. The problem is to overcome the inhibiting mechanisms in the seed parent that bar the progress of pollen from undesirable suitors causing the pollen to die.

A solution to this problem is the so-called 'Mentor pollination method'. Professional breeders place an amount of irradiated pollen on the stigma of the seed parent and this grows down and triggers the 'intruder-alarm system' but cannot fertilize the ovules. The alarm having being turned off, the real pollen is introduced about 24 hours later and all should go according to plan. A variation of this method is suitable for all amateurs and seems to work. Place a very small amount of pollen known to be compatible with the seed parent on the stigma. This should be only a very small amount. The vanguard pollen advances down the style, switches off the rejection mechanism and should allow a free run for the real pollen parent to follow within a 24- or 48-hour period. It may well mean that there is a small percentage of 'unwanted' seed amongst that which is eventually harvested, but this is not a big price to pay - and who knows this seed may give you something good.

Embryo culture

Sometimes pods swell, evenly or unevenly, and when they are opened the expected seed appears to be all chaff. You may think that pollination has failed. This may not be so. Embryos may have formed but be left high and dry by the failure of the supporting endosperm cells to develop. It is perfectly possible for the amateur to 'untimely rip' the embryos from the developing seed pod and to culture them in sterile nutrient mediums until they make small plantlets that can be transferred to normal cultural methods. The job has three main stages:

• to prepare the nutrient solution
• to deliver the embryo from the seed and place it in the medium
• to transfer the plantlets from the medium into growing compost

The embryos can be seen in the transparent seed, especially easily on a light box. The best time to complete the job is while the seed pod is still green yet the embryos are already clearly developed; this could be about eight weeks after pollination, that is 56-60 days. Conditions need to be as sterile as possible.

Tetraploid breeding

We are now at the beginning of a whole new chapter in breeding, with strong new tetraploid plants being bred in several divisions. The normal complement of chromosomes of a lily is 24. These are the diploids, usually noted down as 2n=24. The reproductive gametes, the egg and pollen cells, carry one set of chromosomes, that is n=12. Occasionally in nature and in cultivation, individuals mutate to become triploids, with three sets of chromosomes (3n=36) or become tetraploids (4n=48). Except in very rare cases of mutations, when diploids are crossed diploids are bred. Similarly tetraploids bred together will reproduce plants of similar polyploidy. If a triploid is crossed with a tetraploid and it produces seed one may get both triploids and tetraploids. Diploids crossed with tetraploids can give both triploids and tetraploids. These polyploids vary in their fertility. Pods may have only a few seed. If you wish to mate plants of different chromosome counts, you should plan to use the higher polyploid for the pollen parent.

The difference between diploid and tetraploid plants can be dramatic. Benefits include:

• plant growth more energetic, resulting in stronger stems and foliage
• larger flowers, wider petals, all of thicker texture
• more disease resistance
• longer period of flower
• more productive bulbs
• easier breeding with triploids which should lead to an ever-larger bank of tetraploids

Dangers could include:

• loss of some of the grace of the flower
• in some tetraploids, a tendency for buds to be more brittle, something that hopefully will be bred out as selection takes place