Agree w/ Fruitnut, some of the varieties you mention are known for their winter hardiness, not frost tolerance. Reliance does bloom a few days later here, but given your specifics, that's probably not going to help you. When you're talking frosts, there can be quite a variance in temperature, which is of great significance. Peach blooms can take temps down to about 25F before they're pretty much wiped out. Frost tolerance of various cultivars can be helpful, but it's not huge (probably just a couple degrees difference). If cold blasts of 25F or below are common in your area after bloom, you're fighting a losing battle. You need to either cover your peach trees (with a small greenhouse, as Fruitnut has done, or a high tunnel) or grow later blooming crops - blueberries, blackberries, etc. For several years, I tried to grow fruits that bloomed too early for my locale (apricots, Jap. plums). Every year, I worried for a month if the frosts would take out the fruit (which it generally did). Last summer, I had enough and just removed them all, finally realizing they just weren't suited for this area. Sure they'll fruit every five years, but that's too little return on my time and space. It wasn't worth the worry and hassle. Now if the Spring weather isn't quite so severe, perhaps cultivar selection would be of some help. Of the cultivars you mention, I've grown/grow Reliance and Redhaven. Redhaven isn't any more frost tolerant than any other typical Midwest peach. I pulled Reliance out due to quality issues before it was frost tested. One peach that has shown more frost tolerance than any other peach in my orchard is Redskin. Unfortunately, Redskin harvests late, and so may not ripen in time for your climate. Surecrop not only has a reputation for frost tolerance, but it also ripens early which probably makes it a good fit for you. I needed something in that harvest slot, so I ordered one myself for this Spring.

Sounds like you may be in a pretty bad frost pocket. If kumquats are giving you trouble, you might be in a Zone 9a? We get some frosts in our Zone 15 (9b) but never enough to damage any of our fruit, and we have pomelos, blood oranges, lemons, Navel oranges, mandarins, and Valencia oranges.

Yikes. We could never do this in S. California. There is NO way I would ever have an open, unattended flame out in my orchard. Too many animals walking around at night that could knock over a lit candle and set my orchard on fire. Instead, you're better off stringing a set of incandescent Christmas tree lights (not the LED kind, but the older incandescent type). Then, if your tree is small enough, cover with frost cloth and pile dirt around the cloth at the bottom of the tree, enclosing the fabric completely in dirt to trap in the warmer air. The leaves touching the frost cloth will get nipped, but the tree will be saved. If you're in fear of a real freeze, flood your trees wells with water. The roots then will probably not get below 32 degrees. This and fans is what commercial orchards do now, in place of the old smudge pots - flooding with water and running large fans to keep the air moving. Patty S.

I tried wrapping the trees this year along with Christmas mini lights and it wasn't enough. My thermometer that is about 4 ft off of the ground said the temps got down to 19 one night and 18 about a week later. The peach trees are about 6 ft high. The funny thing is that no more than 50 ft from the peach trees is my plum tree that was mid to post bloom and it only had about a 30% loss. The plum tree is a lot bigger but it is also closer to my house so it is hard to say what factors are making it more hardy. My apples were showing pink and a few buds were starting to bloom but had almost no die off at all. They are not by my house and are actually over the area that the thermometer is in. The apple trees are also very large and were neglected for 30 + years before I bought the house. I have a fence that runs around my yard that is about 6 ft tall and my theory is that it amplifies the effect of the frost pocket and the trees need to be taller than this pocket. Also I am interested in anything that I can to do increase the bud hardiness like feeding them more nitrogen. I have a suspicion that the larger trees trap heat better, like a canopy tree, but I don'y know if this is true. Our freeze events are always radiation events when the air gets real calm after a storm moves out, we are prone to temperature inversions were I live.