Not necessarily. Containers equalize with ambient air temps much faster than the temperature of the earth. A sudden cold snap in which night temps drop to 20* CAN kill a fig under certain circumstances. Your tree is probably safe resting on the ground, down to about 25*. If the ground is frozen or temps drop below the 25* mark, some protection will be advantageous.

Al

Al,

Would you say this is also true of first-year infant cuttings in, say, 1gal pots?

What separates the roots of young plants from the roots of old plants is their state of lignification (woodiness). The roots of young trees are charged with being less resistant to cold, when in fact they have the same resistance as roots on older trees on an age-for-age basis.

If we could magically move the same root back and forth between an old and a young tree, with all else being equal, the root would have an equal measure of hardiness on either tree. The reason young trees are more susceptible to death by freezing is because ALL the roots are young and unable to tolerate temps as low as SOME other roots on larger trees; whereas older trees have older roots that are more hardy and able to withstand more cold.

Illustration: Let's use thickness as a guide to root hardiness. We know this is a logical way to compare roots' resistance to cold because it's the thinnest roots that die first and the thickest that die last. Also allow that tree A, an older tree, has 50% of its root mass concentrated in the size range from 0-1/4" and 50% of its roots from 1/4" to 1" diameter. Tree B, a young tree, has all of it's roots concentrated in the size range from 0-1/4". If a freeze occurs that drives soil temperatures low enough to kill roots from 0-3/16" on the small tree, it will also kill the roots from 0-3/16" on the larger tree. The difference is, the freeze injury leaves the small tree with only 25% of its roots still viable, while the older tree has somewhere near 65% of it's roots still viable. Just a few degrees colder, so roots up to 1/4" would die leaves the fate of the younger tree sealed, while the older tree still has 50% of its entire root system remaining as viable.

You can see that it's not technically the age of the tree that determines hardiness, but the age of the roots. Young succulent roots are simply more susceptible to death by freezing than older roots, regardless of the age of the tree.

You MUST preserve the viability of the young cutting's roots to ensure viability of the organism - it's all they have. In older trees, there is great benefit in preserving ALL roots by keeping temperatures above freezing, but it is not so critical because older plants have the older root mass to 'fall back on' in the event young rootage succumbs to cold. Keep in mind though, that when the fine roots are exposed to killing lows, the tree is set back, both in terms of the late start it gets in spring while it regenerates a new root system, and by virtu of the fact that energy used to regenerate the lost roots WOULD have gone into creating more branch extension and photosynthesizing mass (foliage). The tree can never actually recover from the setback in terms of growth/mass. It is a permanent loss of potential for the tree.

Al