In an effort to track plant development, prior to Visual Bud (the point when the last leaves have unfolded, and the first buds become visible) it is necessary to count the leaves. If you know the total number of leaves on a plant, you can average the number of leaves you need to unfold a day, to determine if you are on schedule. While it may sound complicated at first, you will see it is really quite simple.

Not all factors that influence the number of leaves on a lily are fully understood. We do know that maturity and vernalization (Cooling) play a very important part. When counting leaves you should consider that all lilies purchased from different sources, or coolers may have a different leaf count. You should try to keep these separated, and do an individual leaf count on each lot.

1. Record the average date of stem emergence
2. After bud initiation (when the lily stems are about 5-7 inches tall) the leaves have all formed and are ready to be counted. Select at least two average lilies from each bulb source or different cooling facility.
3. Cut the stem off at pot level and move to a well-lighted area. Now you can begin to count, and record, the number of leaves on each stem. It will be necessary to remove the leaves from the stem to do this. Count all leaves including the ones at the growing point. (You will need a straight pin or large needle and a magnifying glass to do this.) The embryo-like flower buds should be present, if not you will need to wait a week before you try to count leaves again. The lilies will grow and it will be easier to see the flower buds. 
4. Average the number of leaves per stem, in each lot. (If you count two stems per lot, you would add the total number of leaves from the two stems, and divide by the number of stems counted, to obtain the average number of leaves per stem.)
5. Find two or more average lilies from each lot; count and mark the leaves that have unfolded to a 45° angle. Calculate the average number of leaves on these plants; (record this number, as you will need it later). Mark these plants so you don't have to count all the leaves every week, I have seen many ways to mark then from wire rings about 2-3" in diameter placed on the top of the counted leaves, to marking them with a felt pen.
6. Subtract the average determined in step 5, from the average determined in step 4, this will determine the number of leaves left to unfold.
7. Now you need to determine the preferred visible bud date. It takes 30-35 days to open a flower from visible bud. If you want the flowers to open on Palm Sunday you would subtract 30-35 days from Palm Sunday, this would be the date you want visible bud to occur.
8. Divide the number of leaves unfolded, by the number of days from emergence (step 1). This will tell how many leaves per day you have been unfolding under your past temperatures.
9. Count the days left to visible bud date (step 7).
10. Divide the number of leaves left to unfold, by the number of days until visible bud (step 7). This tells you how many leaves you must unfold each day until visible bud. Compare this number to the leaves per day determined in (step 8) which should be between 1 and 2 leaves per day. You may need to adjust forcing temperatures accordingly to unfold the correct number of leaves per day. 
11. Continue to determine how many leaves per day you are unfolding. Each week, continue to count the new leaves on the plants you marked earlier in (step5) to a 45° angle. Add the leaves together by lot, divide this number by the number of lilies counted in the lot. Divide this number by the number of days in the previous week. This will tell you how many leaves per day you have unfolded since last counting. Compare this to (step10), hopefully they are close if not you will have to adjust the temperature accordingly.