Re: frozen plants
I don't understand your reference to hardening off a rhododendron.
Previously I've only heard the term used with reference to acclimatizing
herbaceous plants to the outdoors from indoors or vice versa. Never heard
it referring to a woody shrub before. Could you please explain? I'm also
challenged by your comment that dry soil freezes deeper than moist soil.
"As water freezes, it releases heat which will slow the penetration of
frost." But isn't that heat release rather momentary? If you have prolonged
minus 20 degrees F with no snow cover, for instance, wouldn't the soil
freezing go to the same depth? Thanks, Margaret L
09:49 AM 1/17/2000 -0500, you wrote:
>Not mentioned except by inference is how plants harden off and the
>timing of the process. Although Rhododendron maximum, for example,
>when hardened off is hardy to -35F, an early freeze can cause
>damage at much higher temperatures. Cornus stolinifera from
>northern strains begin this process before southern strains so,
>although the same species, the plants differ in their hardiness.
>Hence the recommendation to buy locally grown shrubs rather than
>those brought in from warmer zones. AS mentioned, if the ground is
>frozen any water loss cannot be replenished. So those beautiful
>sunny days in March which are so pleasant for us, can be the death
>of evergreen shrubs. I think there are two reasons for seeing that
>such plants go into winter well watered. One is to provide that
>reserve of water, the other is that moist soil will not freeze as
>deeply as dry soil. As water freezes, it releases heat which will
>slow the penetration of frost. to further protect the soil from
>freezing we use a mulch. It takes four times as long for the
>temperature wave to penetrate two inches as it does for one inch.
>
>I think the hardiness of perennials is different. Aside from the
>frost heaving which we want to prevent, I think too much moisture
>in the soil can be detrimental.
>
>
>Bill Plummer
>Painted Post, New York
>Zone 5
>
>
