Testing for frost?

I’m looking at a few sites for an orchard. It’s just a family orchard, not too large. Anyway I wanted to know if there’s an easy way to check for frost. I noticed a big difference in microclimate, even 75 feet Can be the difference between a frost and a harvest.

I noticed car windows show frost or not, and was wondering if I could place something like mason jars in potential orchard locations, to see if there’s one place that more sheltered than the rest?

I do have some southern facing hills with giant sagebrush on it, it’s just very untouched by man and will need some terracing done. But maybe the terracing will be helpful in harvest? Of course others in the family think the flat land is easily harvested, but I am hesitant because one hard late frost would make ease of harvest a moot point.

Sorry about spelling,ect, my new phone wants to make a fool of me.

Hello Nicole
Just guessing on the basis of mentioning sage brush what your climate might be.
I encourage those new to permies to go to their profile link at the top of the page and fill in what location information they would like to have appear with their name when posting.
I use high low registering thermometers  to log each day but there digital ones to do it automatically.
As the heated hillside cools  by radiation to the cool sky, air that is warmed by rocks will rise as cold air falls in the valleys on the hillside.   The warm air prefers to flow up under the trees where the ground does not radiate the heat to the sky.
So map out the potential flows this spring and log the differences.

Hi Hans

Thanks for the suggestion about the profile; I totally skipped that step.

The area is a river valley in a high desert in Southern Idaho. The valley has tiered flat stretches with some places being volcanic rock hillside (which has largely been untouched). Some areas are irrigated farmed, and there’s also a couple of wetlands with natural seep springs and tulles which feeds the irrigation.

Once upon a time there were apple orchards on the fields but the climate has gotten a bit cooler in the spring, and late frosts are notorious for killing off buds. It’s seeded to alfalfa now.

People still have mixed success with fruit trees, mainly due to frost. What you say about the thermal flow makes a whole lot of sense.

I’ll see what I can find for a thermometer like you mentioned. If they’re affordable enough, I’ll grab a few to get relative reads on the same nights in different sites.

the planting on terraces idea is my vote. anything that will ‘drain’ cold air will likely be better than your flat area.

I’m thinking of going with this hillside. If you look below the tree with the yellowish branches, you’ll see a huge old mess of blackberries that are progressively invading the hillside and which therefore the family wishes to be rid of. It’s unfortunately on what may well be the best place for an orchard. (I’ve spent several years ridding gardens of brambles and am under no false pretenses about the task I’m up against). My father apparently sprayed it enough to kill 95% off it then tried to bulldoze it but kept hitting rocks so stopped. His current plan is to mini escavator a fire barrier then wait for a rainy day to light the thing up.

The hillside is mostly southward facing, a little SE.
it’s the warmest place on the farm and least windy. THe soil is silty loam.

Though I couldn’t really see it due to the vegetation, apparently the contour of the landscape is bowl-like within the hill. It had a walnut tree growing until the bramble killed it. I saw the walnuts still on the ground.

It gets seep spring like water when the neighbors irrigate their fields.

One of the bonuses of this hillside is that it isn’t currently being used so it isn’t like we’re sacrificing good pasture or farm land . And then I just feel more at peace up there.

You'll certainly have a sun trap with that hillside.
Hopefully the seepage from the neighbours will be a benefit rather than a downside - depends what else they put on their fields...

I understand that sometimes it's not the frost so much as the rising sun hitting the frozen blossom that does the damage for fruiting. Later blossoming fruit tree varieties are one way around the issue. I found some threads that may help:
https://permies.com/t/165574/Late-blooming-fruit-trees-frost
https://permies.com/t/161292/Sloped-flat-land-permaculture-market#1264258
https://permies.com/t/159308
https://permies.com/t/154688/Fruit-trees-southern-slope#1211896

I'm amazed that brambles could have killed a walnut tree! It sounds like you have monster vines there!

Nancy Reading wrote:You'll certainly have a sun trap with that hillside.
Hopefully the seepage from the neighbours will be a benefit rather than a downside - depends what else they put on their fields...

I understand that sometimes it's not the frost so much as the rising sun hitting the frozen blossom that does the damage for fruiting. Later blossoming fruit tree varieties are one way around the issue. I found some threads that may help:
https://permies.com/t/165574/Late-blooming-fruit-trees-frost
https://permies.com/t/161292/Sloped-flat-land-permaculture-market#1264258
https://permies.com/t/159308
https://permies.com/t/154688/Fruit-trees-southern-slope#1211896

I'm amazed that brambles could have killed a walnut tree! It sounds like you have monster vines there!

Hi Nancy! The reading list you provided was really insightful, and it lead to me checking for frost resistant fruit trees (duh! Why didn’t I think of that earlier?) which lead me to….

https://www.extension.uidaho.edu/publishing/pdf/BUL/BUL0867.pdf

A list of trees for Idaho by the University of Idaho!

I’ve already ordered some apple trees (none made the list on the above document but oh well) and sweet cherries (which again aren’t advised on the above list) but which I know from neighbors experience do work more often than not.

However I think i will pick varieties from the University of Idaho list for stone fruits, ect.

I’m not sure if I’ll try things like painting the trunks and whatnot. Maybe.

As far as tree varieties go, mostly my trees are in flowering group 3, but I do have one early tree and the crabapple starts in group 1. If I decide my current varieties are too susceptible I’ll try frost restraint varieties.

But I think I’ll stick with the hillside as my spot. It just feels right.

Oh the brambles are something else! They’re close to 14’ tall if not more than that, and a good 26’ across. You could hide a small house under them. I think the walnut was fairly young, but old enough to give a decent crop of nuts.