Check Flowers of Fruit Trees for Freeze Losses

Myer lemon (not a true lemon) fruit ready for harvest. Its orange color and round shape shows off its orange fruit heritage.

Why doesn’t my ‘Meyer’ lemon tree produce any fruit? 

I was reminded of this question when I estimated the fruit production this year in a Las Vegas Orchard. I use a particular variety of pluot called ‘Flavor Supreme’ as an “indicator tree” for predicting the probable fruit load that year. I saw no fruit developing and I saw no remnants of flowers on these trees. I knew there was a late freeze that came through that orchard during the spring, probably two or three weeks ago.

Tearing open a flower soon after suspected freeze damage will tell you if the fruit will fall off dead or it is alive. In this case the ovary inside is green so it shows the flower will most likely produce a fruit.

           How did I know all that and how do I relate it back to ‘Meyer’ lemon? First of all, recognize it only takes a 1 or 2°F difference in temperature between having a tree loaded with fruit versus having a tree with few fruit. If this temperature difference comes along two or three times during the spring when it’s trying to flower, then voilà, there is no fruit produced that year.

All Flowers are Sensitive to Freezing

           The most tender parts to freezing temperatures of any fruit tree is its flowers. When flowers are open is the time when it is most sensitive to freezing temperatures. The tree itself is usually fine but not the flowers. If a very light freeze occurs in the spring only once when the tree is flowering, then fruit production is reduced. If a light freeze happens two or three times, maybe a week apart during the spring, then the fruit is probably eliminated for that year. However, if there is a single “hard” freeze (4 or 5 degrees below freezing or more) as flower buds are “awake” then, most likely, all fruit will be eliminated for that year.

           Flowers are killed by freezing temperatures depending on their stage of development. Flower buds during the dead of winter are very tolerant to freezing temperatures. But in the spring, when the plant begins to “wake up” from its winter sleep, they become more and more sensitive to freezing temperatures as they approach opening.

Open flowers are the most sensitive to freezing temperatures; 1°F below freezing for a very short time kills the single chance it has for fruit. Once a flower dies, it cannot produce fruit. If the flowering time of a fruit tree lasts three weeks, then it has a better chance to produce fruit as more flowers continue to open. If only 5% of the flowers are needed to produce a full load of fruit and all the flowers are dead, there is no fruit for that year.