Compared to Lilium, very few plant genera possess the amenability to various propagation means. In addition to the most common means of propagation, which is growing plants from their seeds, it is possible to grow lilies from daughter bulbs that emerge from the primary bulb. The scaling process of propagation involves detaching parts of the bulb and inducing them to generate new bulbs.
Propagating lilies using the vegetative scaling method is not only most cost-efficient, but also helps to rapidly increase clones. In fact, commercial lily growers extensively employ scaling, as they are of the view that this method of propagation revitalizes their stock. In addition, provided the method is undertaken properly, it also has a cleansing effect. In the process, scaling also helps to control diseases like basal rot (also known as Fusarium). Often, scaling is used to enhance a group of exceptional lilies that have been picked from within a particular seed strain. It is possible to readily propagate nearly all types of lilies from their bulb scales.
It is essential to select vigorous bulbs with no trace of any disease for propagation by means of scaling. However, this means of propagation does not afford any protection from transmission of viral or any other type of diseases. In fact, it would be a blunder if one tries to propagate lilies from materials that have any type of symptoms of serious diseases.
You should ensure that the lily bulbs you have chosen for scaling are cleanest possible. You need to wash away all soil that may be attached to the bulbs. You will be able to obtain excellent results by choosing the largest bulbs from a stock. In addition, they need to be vigorous and strong, besides being maintained optimally.
It is very important to break off the scales cleanly at the very basal plate if you wish to promote formation of maximum number of bulblets. Since the scales are arranged spirally, it is best to remove them around the bulb - in the same manner in which you dismember an artichoke. If you adopt the scaling method of propagation, it can be undertaken during any time of the year. On the contrary, scaling largely depends on the conditions prevailing in your area as well as the grower's personal fondness.
Provided the grower applies the right stimulations, the scales will lead to formation of bulblets at any time. However, it is important to bear in mind that the scales of lily bulbs decompose very quickly if the levels of moisture as well as the temperature are not favourable.
If you want to plant the scales outdoors, it is best to take them out from the ground immediately after the plant completes flowering. When you do this, you allow the bulbs sufficient time to develop a callus as well as new bulblets prior to the onset of the very cold weather. It is important to remember that though the growing conditions differ greatly, it would be best if you allow the bulblets no less than two to three months of excellent growing weather for the scales planted in the ground to succeed. Hence, it is never advised to undertake the scaling method of propagation for Orientals that flower later in the season. However, it is possible to grow the scaled even from these lilies in the same way provided you cover the scale beds with frames or any other protective means. While propagating lilies from scales, it is crucial to always maintain the moisture of the soil evenly, especially after you have planted the scales. In fact, this is a vital condition for developing new plants from scales.
While the direct planting method works excellently for amateur lily growers, commercial growers seldom use this process. However, there is an exception - for instance, Lilium candidum or the Madonna lily. Scales of this lily are usually planted directly because they grow leaves soon after the development of the bulblets. This variety of lily only responds well to the direct planting method of scaling. Numerous growers have been able to reap exceptional crops of this outstanding lily by scaling its bulbs towards the end of June or beginning of July and by planting the scales in beds or rows. However, you need to provide sufficient irrigation after planting the scales of Madonna lily. Provided you have taken adequate care, the scales will yield large bulblets and subsequently overwintering leaves. The new plants will produce beautiful flowers in June next year.
Earlier, the commercial scaling method involved lifting the bulbs towards the end of summer or in fall. Subsequently, the scales were removed and put into an incubation period lasting for anything between 8 weeks and 12 weeks. This was followed by vernalization, wherein the scales were placed in cold storage for about another 8 weeks to 12 weeks. Finally, the scales were planted in spring next year. In fact, this may possibly be one of the easiest methods of propagating lilies, especially for an amateur grower. Currently commercial growers usually remove the scale from the bulbs after harvesting them either towards the end of fall or beginning of winter. If you are adopting the latter method, you need to follow the steps mentioned below very carefully.
Make sure that you only clean the large bulbs that are disease free and have been obtained from stocks, which have been verified true to their name. Break off the scales cleanly right at the basal plate in order to allow formation of good bulblets. You should also dip or dust the scales in an appropriate fungicide, such as thiabendazole (also called TBZ) to get rid of any possible viral infections. For several years now, Mertect has been successfully used as an effective dip by numerous lily growers. Store the removed scales in thin layers in any moist medium and place them in boxes and trays. Both vermiculite and sphagnum peat are wonderful media and they should cover the scales completely. In addition, you should line the containers using punctured plastic liner as this will help to conserve moisture and also serve as a vent to allow good air circulation. This is one of the most vital factors for developing bulblets and roots successfully.
During their incubation period the scales should be kept in a room with adequate ventilation and at temperatures between 15°C and 21°C (60°F and 70°F). Allow the scales to remain in incubation till they form complete bulblets and develop good roots. The period for which the scales should be kept in incubation largely depends on the variety of lily you are propagating. For instance, Asiatic hybrids need an incubation period of 6 weeks to 8 weeks, while the duration is 8 weeks to 10 weeks for trumpet species and their hybrids. Similarly, the Oriental species and their hybrids require an incubation period of anything between 12 weeks and 14 weeks.
Trumpet hybrids, on the other hand, do not need a cold period for developing its shoots. Nevertheless, you need to watch them closely and take them away from the incubator as soon as the bulblets are formed fully. You can also scale the bulbs of trumpet lilies in the beginning of spring and plant the scales directly outdoors in rows. When the soil is warm enough, they will start forming bulblets. The leaves will emerge after the bulblets have developed fully. It is possible to obtain excellent growth of trumpet lilies propagated in this method in the same season.
After you take out the trays containing scales along with bulblets from the incubator, you need to store them at a transitional temperature ranging between 4°C and 10°C (40°F and 50°F) for a period of anything between three weeks and four weeks, and subsequently put them in cold storage at 1°C (34°F). The smallest vernalization period needed to end the dormancy of the bulblets differs. While the minimum period is about 6 weeks for Asiatic lilies, in the case of Oriental lilies, this varies from 12 weeks to 14 weeks. However, allowing the scales to remain in cold storage for a longer period is not harmful for them. In the case of trumpet lilies and their hybrids you do not need keep the scales in cold to bring them out of dormancy. In fact, they should always be kept in a somewhat elevated temperature levels, about 2°C (36°F) - however, the temperature should be low enough to discourage sprouting till the time of their planting. You can plant the scales outdoors in beds or rows when you find that the temperatures as well as other conditions are favourable. By this time, the bulblets will have been accustomed to sprout voluntarily. Therefore, it is important that you do not plant them very early or expose the bulblets to frosts, as this will damage them.
Usually, scale plantings are left undisturbed in the ground for about two growing seasons. Several Asiatic lilies can generate flowering stalks in the same season that the bulblets are planted. This is considered to be a sign of better vigour in the newly developed clones.
Characteristically, round lily bulbs send their flowering stalks from their basal plate through the middle of the bulbs. Usually, there will be a solitary or several embryonic growing points in the region of the stem's base. In a number of lily varieties, new bulbs emerge from the buds found encircling the rim of the basal plate of the bulbs, which later develop as replacements for the existing bulbs in the next season. It is worth mentioning here that all the lily species and their hybrids reproduce at their individual pace. While a very small bulb of a weak species or a stressed bulb may generate only one bulb, even two fresh bulbs is very normal. On the other hand, a really vigorous, happy bulb may produce more than six new bulbs.
Ideally the bulbs are lifted at the end of summer. Once you have excavated the bulbs you will see new bulbs still attached to their basal plate. However, you can separate them easily - just snap them off or cut them. If you allow the bulbs to remain in the ground for about two seasons before lifting them, you will find that the tissue that connected the original bulb with the new one will have perished. In addition, you will find that the bulbs from the previous season have already reproduced, giving rise to its successors.
If you are propagating the rhizomatous Lilium pardalinum as well as its close relatives, the best way to divide their bulbs is by cutting them using a sharp knife in such a manner that each severed part contains no less than one growing point. In addition, you need to ensure that each severed piece should also gave a cluster of smaller, budding, white or light cream hued scales - different from the nicotine-hued scales. You need to lift the rhizomatous bulbs as carefully as an archaeologist may possibly do while unearthing some valuable artefact. This is crucial because the scales of rhizomatous bulbs are very easily broken. The stems of these lilies are cut down to one-third of their original length and they usually serve as effective handles to lift the bulbs. When you lift the bulbs at this stage, you will find a fresh flush of roots, which are just emerging from the scales' base. Lifting the scales early will not cause any harm to their roots, as they will continue to grow fast when they are separated into pieces and replanted. However, you need to ensure that you water the replanted scales appropriately.
It has been found that the Asiatic lily species and hybrids, especially the species like Lilium bulbiferum, Lilium davidii and Lilium dauricum, which are known to be the ancestors of these races, benefit most when their bulbs are lifted and divided on a regular basis. You may lift these lily varieties towards the end of summer, split their bulbs and replant them in new sites or even continue to grow them in their original positions. However, if you want to replant the divided bulbs in their former positions, you need to dig the place properly and invigorate the soil by adding liberal amounts of humus.
Experience has taught that once the bulbs of Lilium hansonii, Lilium martagon and their respective hybrids are established and start growing robustly, it would be wise to leave them undisturbed. It is quite easy to find how this particular approach has developed. If you are propagating lilies from their seeds, it is likely to take several years to obtain freely blooming bulbs. On the other hand, if you purchase bulbs from commercial growers or dealers, it is likely that they have already spent some time in storage before reaching you and, therefore, they may not grow and emerge above the soil surface before spending almost an entire year. However, they will be certainly developing a root system under the soil and will send up a flowering stem in the following year. Therefore, the easiest and fasted means to propagate lilies is perhaps by bulb scales or bulb divisions.