The highest concentration of production is in the vicinity of Reedley near Fresno where average summer highs are upper 90s. A couple times a month it’s usually over 100. So I won’t really say they stop growing over 100. The growers get concerned about internal breakdown of the fruit above about 110F.
Michigan peaches probably aren’t as sweet as CA. But mid 80s for highs are warm enough for good peaches. It’s areas near the coast of CA with highs in the 70s that quality really declines. Heat is an important factor in peach production.
a mature peach tree with a full crop can drink 40 gallons of water a day the last couple of weeks leading up to harvest. so you need water as the fruit ripens. But, the reason the south produces great peaches is because of the heat and humidity. This year i noticed that peaches from the bottom of my trees (shaded) were less sweet than the peaches at the top that got more sun. Only average, the brix was 3-4 points higher. Found another reason to prune more.
I’ll bet that has something to do with the nighttime temperatures, otherwise Phoenix and Las Vegas would be famous for their peaches.
Oddly, my Southern relatives once mentioned to me in passing that New Jersey peaches were the best, as if that were a matter of conventional wisdom. (based on their living there for a short period of time). I thought it odd, as they were from Atlanta.
Hi Josh, I came across this while researching peaches/nectarines in the Bay Area. I’m in SE San Francisco (one of the warmest parts), and was considering putting a Double Delight against a south-facing concrete wall.
Did you have any luck with yours in Oakland? It sounds like a similar climate.