Q. Attached is a picture of my Kumquat tree.  I apologize for the picture as there is a lot of other shrubs around the tree making it hard to get a good picture of the tree.  It has been planted for approximately three years and is 5-6 feet tall.  The picture is facing North.  Just within the last year we have had very little fruit whereas prior to that the tree was ample with fruit.  There has been no change to the water schedule (3 days per week for 45 min. each).  The tree appears to be healthy, just no fruit.      Readers kumquat tree The only difference I can think of is that in previous years I covered the tree whenever the temperature was below freezing; however, this past year I only covered it when the temperature fell to the upper 20s.  I think this tree is able to withstand these types of temperatures though.   Any advice you might have would be greatly appreciated. A. Kumquat is a very winter hardy citrus and can survive most winter temperatures here without any problems provided it is in a sheltered spot. It is considered one of the more cold tolerant of the citrus. The key question you have to ask yourself is whether it produced any flowers are not this year. The major reasons for fruit drop are temperature and irrigation problems. If we have freezing temperatures or if the plants become water stressed from not enough water, they tend to drop fruit if it was produced or even flowers. Flower buds and fruits are much less hardy to freezing temperatures than the plant itself. Kumquat may produce fruit all through the year but tend to produce fruit in the spring and fall months and through the winter. If it does get some winter damage, you would’ve seen die back. The plant will regrow to the height it was before it had damage with very few flowers. Once it reestablishes the size of had before, it will then begin to flower again more profusely and produce fruit.  If there were some spring freezes the flower buds would be killed before anything else would show any damage. This would tend to minimize fruit production. If the plant receives a lot of fertilizer, particularly nitrogen, it may tend to put on new growth with few flowers and of course very little if any fruit.