In North America, decreasing year to year tulip flowering is a very common problem across the Midwest and points further east, locations that always receive more than enough cooling. The descriptions are nearly always the same with 100% flowering the first year after planting with a rapid decline in flowering thereafter. In general, one of the responses of flowering size tulips bulbs to adequate venalization is to divide into smaller bulbs. In the Midwest, spring is very short and quickly followed by hot summers. Late spring high temperatures induce tulip leaves to senesce too soon, long before the young daughter bulbs have grown large enough for flower induction. Instead of flowering plants, multiple leaves are produced the following spring from a clump of small bulbs where each original bulb was planted. For many tulip cultivars, repeat flowering is virtually impossible because the bulbs constantly divide year after year, never achieving an adequate size for flowering. In the Midwest, this problem can primarily be avoided with proper tulip selection and, to a lesser degree, with adequate fertilization. Houston is not in the Midwest and concerns about inadequate cooling are legitimately cause for concern. However, remember that 100% of Sujit's bulbs flowered the first year and 70% flowered the second year. In those years, at least, the bulbs did receive enough cooling to flower. We don't really know what happened the first year since the bulbs may have been partially precooled before they were purchased, but the bulbs did receive enough cooling the second year to result in 70% flowering. Furthermore, the flowering stalks were the height that was expected of them. This is key information since the height of the flower stalk at the time of flowering for many bulb plants, especially tulips, is primarily influenced by the amount of prior vernalization. Cooling does not cause flower induction in tulips. Warm temperatures during the previous summer induce flowering which is not ever going to be a problem in Houston. Cooling is required for elongation of the flowering stalk. Too little cooling can result in very short flowering stalks with flowers down very low among the leaves. Even less cooling results in aborted flower buds. (Too much cooling causes very tall floppy tulips.) Between the 70% flowering reported for the second year and the normal heights of the flowers, Sujit's plants seem to be getting enough cooling. Also, it's possible that only 70% of the original bulbs survived and 100% of those remaining flowered the second year. Now that we know that this tulip population has thinned since planting, it's safe to say that other cultural requirements are not being met. A thinning tulip population implies that the average bulb size is decreasing. Bulb size is everything if you want flowers. This point cannot be stressed enough. Especially in areas with marginal cooling, larger bulbs are especially important for successful flowering. Fertilizing is always extremely helpful in producing large tulip bulbs. There are plenty of online recommendations for properly fertilizing tulips. In summary, inadequate cooling does not seem to be the problem here. One or more other cultural requirements (e.g. fertilization, irrigation, lack of pests) is not being met resulting in a declining population with bulbs that are no longer large enough to flower. Nathan At 04:36 AM 4/15/2016, you wrote: >All, > >Thank you for all the responses and advice. The flowers from the first >year were at the height I expected and so were the second year but much >fewer. Now the population have thinned with only healthy leaves. I will >experiment with some of the suggestions. Lifting some in the fall and chill >and replant in the spring and also fertilizing the rest in the fall. I will >report the results next spring. > >I will put one of the Buphone in the ground. > >Warren, I will try to call you this evening. > >Sujit