Peach flower open and ready for a pollinator. Nectarines are peaches without any fuzz on the skin. This was taken on February 1 in the Eastern Mojave Desert. There is a danger of frost until the middle of March. This is the most sensitive stage in fruit development to freezing temperatures.  Q. I live in San Tan Valley, Arizona, and have a Panamint Nectarine that, even though it flowers, has never produced fruit. It is about 7 years old. I keep it pruned to about 8′ ft. with an open center style.  My Katy apricot grows about 8′ ft away and sets tasty fruit every year.  I am resigned to the fact that I will never taste a Panamint nectarine. The local nursery says were at about 500 chill hours. Nectarine but I don’t remember which variety. A. The fact that your tree flowered and didn’t produce fruit is a critical piece of information. People contact me and tell me their fruit trees don’t produce fruit, but they fail to tell me if it flowered or not. If a fruit tree doesn’t flower, it’s one set of problems. If it flowers but doesn’t set fruit, then it’s a different set of problems.             Your nectarine tree flowered. If it had lots of flowers, then I doubt if it’s a lack of chilling hours. Panamint nectarine is self-fruitful, it just needs bees present when it flowers. If there are a lack of pollinators, then you will get a very poor fruit set. Whenever lots of bees are present at the time of flowering and there are no other problems, you get lots of fruit. Nectarine new fruit developing after pollination.             Late spring freezes can be a problem with some varieties of all fruit trees. Some varieties are more sensitive to freezing temperatures than others. This can be true of some varieties of peaches and nectarines.             It can also be true of your location. If you are located in low areas where cold air can accumulate, there is a greater chance of having late spring frosts. Trees that are on slopes where cold air can drain away from them are less likely to have losses due to late spring frost. The most critical time temperature-wise is when the flower is open and through anthesis, i.e. when the petals fall from the flowers. Arctic star nectarine in bloom about ten years old but pruned to open center and kept below 8 feet tall.             Tolerance to colder temperatures is greater before the flower opens and after the newly formed fruit has had a chance to gain some size. We are talking only a couple of degrees Fahrenheit but that can mean the difference between setting fruit and not setting fruit. Immediately after anthesis..when the petals fall from the flower. This peach flower was pollinated and the pitcher-shaped receptable has swollen and ready to grow into a peach fruit. Freezing temperatures, dipping below 32° F, can easily kill this tender receptacle at this stage and cause the flowers to drop from the tree without producing any fruit.             I never liked Panamint very much. I had them growing at the University orchard and pulled them out after they fruited a few years. I don’t like the tree and I didn’t like the fruit. Nectarine fruit developing             After that many tries and getting flowering but no fruit, I would get rid of it. My favorite nectarine so far is Arctic Star. It is a white nectarine with wonderful flavor and aroma. It is one of my favorite fruits of all time. I never had a problem with fruit setting even when other fruit was lost due to late spring frost.             I don’t agree 100% that chilling hours is that important for several types of fruit. Perhaps some fruit trees are not as sensitive to chilling hours as others. I don’t know. I am growing peaches with 900 chilling hours for 20 years and we have about 300 units in Las Vegas.