The Latest Dirt - Nov 2022

Peach Tree Starts Flowering in October

By Sarah Hoyer

Client’s question
I have a peach tree I planted two years ago. Last spring it had many blossoms until there was a cold snap. Then only one blossom managed to make a fruit. I was just looking at the tree and noticed it has a dozen or so blooms (in October!). Should I remove these, as they are very unlikely to make fruit?

Sarah Hoyer’s response
Thank you for contacting the UC Master Gardener Program Help Desk with your peach tree question. You describe your two-year-old tree as having many blossoms last spring, but only producing one peach because of an untimely cold snap. Now, in October, the tree is producing blossoms once again. Your question is whether you should remove the blossoms.

Fall flowering is somewhat uncommon but when it happens it is not usually of great concern. This phenomenon is most commonly found in apple trees, but it can happen with many other types of fruit trees in the Rosacea (rose) family. These include peaches, nectarines, pears, apricots, plums, and cherries. It is not necessary to remove the blooms because, as you mentioned in your email, they are not going to produce fruit this late in the season.

This is a brief explanation of why fall blooming is thought to happen. Spring-blooming fruit trees begin to form their flower buds for the next season’s fruit in the summer. Environmental stresses, such as heat or drought, can cause a tree to go into a temporary summer dormancy. In the fall when the temperatures cool, the tree will sometimes be “fooled” into beginning to bloom. Those of us who garden here in Contra Costa County have certainly experienced drought conditions in the past several years and have also had to contend with some episodes of severe summer heat.

Here is an excellent article that goes into greater detail about the cause of season blooming. It discusses the phenomenon as seen in the Northeast and Midwest, so not all the information it contains applies to plants grown in our area of California.
https://yaleclimateconnections.org/2020/12/what-causes-flowers-to-bloom-in-the-fall/

The reason why the fall bloom you are seeing is not of great concern is that peach trees will usually produce many more blooms than necessary. In most seasons, the excess fruit produced must be thinned when still small— about ¾ to 1 inch in size. This protects the tree from branches breaking due to an overload of heavy fruit and allows the remaining fruit to reach a good size. So, while the fall blooming will cut down on the flower buds that remain to bloom in the spring, there should be plenty left to provide a peach harvest from your young tree. I do advise that you do serious fruit thinning and allow just a small number of peaches to be produced on young trees that have not developed the strong branches needed to support the weight of the heavy fruit.

While fall bloom may not be completely avoidable, proper irrigation techniques and cultural care would certainly be a place to start. Not only with the fall bloom, but for the life of the tree and future bountiful harvests. This information from University of California may be helpful. It contains a huge amount of valuable information on growing many varieties of fruit trees, including the care of young trees in their first years, irrigation, pruning, and fruit thinning.
https://homeorchard.ucanr.edu/The_Big_Picture/

Please feel free to contact us again if you have further questions or concerns.