What soil is most freeze resistant?

[Mike Corazzi]

I primarily use lava with a ....little.... organic stuff. And some charcoal and bone meal.

I don't even know if freezing should be a concern.
I have heard that pines don't mind freezing solid in the winter although I've always covered the pots.

I have had lousy results from akadama but for reasons other than freezing.

How does turface or more organic soil work? I would GUESS the organic would freeze easier due to water retention but then I started thinking about CIRCULATION of freezing air through lava.

?????????

 

[Jester217300]

If there are freezing temps outside most soils in pots will freeze at a similar rate. I'd say organic dense soil would freeze SLOWER than an open soil like lava. Lava lets the freezing air in to the center of the rootball so everything freezes evenly whereas organic soils have less air penetration and would freeze from the outside in.

Regardless, do what is best for your trees in your climate during the growing season. If you're worried about a hard freeze water your trees well beforehand. Freezing is almost never the problem. Instead you should be concerned of dry, desiccating wind / air.

I keep my pots packed with snow or ice during winter. In CA if freezing is a risk I'd water in the evening and then ice the top of the pots. Freezing solid is very much preferential to exposing the roots to freezing, dry air. The retained water in the pot that freezes is actually what protects the root system.

 

[Dav4]

In my experience, turface and lava don't degrade due to freezing, though over many years they probably will but it's never been an issue for my trees. Also, temperate pines don't mind having frozen toes for months on end as long as they're out of the wind and sun.

 

[Mike Corazzi]

Out of the wind and.....SUN ???????

 

[Dav4]

Out of the wind and.....SUN ???????

If the soil is frozen for days on end then...YUP!!! It really depends on your climate.

 

[Mike Corazzi]

Everything thaws by 10 AM or so.

 

[Dav4]

You answered your own question...