Most modern day Asiatic lilies tend to exhibit strong vigour and excel in reproducing themselves. Many varieties will need to be lifted every second year as they tend to produce many stems and the small bulblets start to crowd the original bulb. However there are some varieties which have trouble multiplying, and which are in trouble if nature turns unkindly. To offset the possible elimination of these varieties there are a few tricks that come in handy and which are easily accomplished.
A somewhat desperate method - during mid-season dig down alongside one side of the stem and the bulb, be very careful, carefully cut the stem completely through just above the bulb - try not to disturb the bulb. This will leave the plant still growing but with out the bulb to nurture. The plant will usually produce a number of small bulblets by fall. These bulblets then can be taken up in September and reset for growing-on.
This is a method for quickly increasing a variety. This technique is used by many commercial growers. It is also a good practice to use when you purchase a rare and/or expensive bulb. Rather than leaving the one bulb to Nature's vagaries try scaling it so there will be back-up bulblets if something might go wrong with the parent bulb.
Scaling is best accomplished in the fall when mature bulbs are normally planted; dug and reset. By gently snapping the outer ring of scales off at the basal plate one will often obtain anywhere from 5 to 10 scales. It is essential that the entire scale, and particularly the bottom portion of the scale, is taken.
Any scales showing hints of disease or damage should be discarded as they are unlikely to reproduce. Refrain from taking more than the outer ring as the bulb will be weakened. Put the scales in a small plastic bag which contains peat moss damp enough to maintain a ball when squeezed. It helps to add about 1/2 a teaspoon of bulb fungicide to the scales and then shake the scales through the peat moss. Tie the bag tightly and then put it in another plastic bag with a label.
If the scale package is put into the fridge crisper in September or early October for vernalization it can be taken out in late December. Some varieties do not even require this step but it is the most reliable method. Place in a warm and usually dark place (the furnace room is an ideal location), check once during the winter to make certain that the peat moss is still somewhat damp, and watch for tiny roots to start showing inside the bags. There is no need to do anything further unless green shoots start to appear. The fine rootlets indicate that the bulblets are growing and will either have to be planted up or put back in the fridge to await spring planting. When the time comes separate the mass of roots and bulblets and plant them about 1 inch deep.
Occasionally first-year bulbs will produce a bloom or two, but generally it is in the second year that they start to flower; and they may even have a mature-sized bulb below.
It should be noted that in some cases the same scale can be used a second time to produce bulblets, but generally the scale is dessicated as the nutrients in it are taken up by the developing bulblet(s).
Varieties of Lilium tigrinum parentage will grow stem bulbils in the leaf axils. While most "Tiger" varieties reproduce readily, these stem bulbils offer an opportunity to rapidly increase stock. As the plant matures by late summer remove the bulbils and simply plant them about 1 inch deep. The next spring will see shoots emerging as the new stock of lilies develop.
written by Art Delahey, CPLS and Riverside Gardens