That's a good question, Hugh. I didn't have fruit trees for 30 years and just have one white peach, now. It produced a surprising amount of wonderful fruit the last 2 years.

There's some fruit tree information from the University of Connecticut linked below. They say "Peach trees are very vulnerable to cold weather" but I think they are talking about over-winter temperatures, mostly.

However, for all stone fruit: "As the fruit buds grow and open, they become more susceptible to frost injury. The exposed buds can usually withstand temperatures near 24 degrees F, but blossoms of practically all fruit trees will be killed if the temperature drops below 24 degrees F."

We don't have extreme cold in the forecast here but the buds are really beginning to swell. I'll follow UConn's advice if it does: "When a heavy frost is expected, covering the trees will sometimes prevent bud or blossom injury . . ."

I hope others have more experience that they can share so that we are better prepared.

Steve

Here is a link that might be useful: UConn, Fruit Trees

Yup. If the flower is liquefied it cannot get pollinated and make a fruit. It may be able to bloom again, albeit at a lesser number of fls.

Dan

Here's a link to a Michigan State U Extension site with frost hardiness info for apples, plums, peaches, etc. at different bud stages. As the buds develop, they become much less cold hardy.

Ian

Here is a link that might be useful: MSU Frost Hardiness Data