gixxerific wrote:Here is what Wiki say's about the actual temps and their severity. Though these seem rather low compared to other places I have seen it.
slight frost: 0 to âˆ’3.5 Â°C (32.0 to 25.7 Â°F)
moderate frost: âˆ’3.6 to âˆ’6.5 Â°C (25.6 to 20.3 Â°F)
severe frost: âˆ’6.6 to âˆ’11.5 Â°C (20.2 to 11.3 Â°F)
very severe frost: below âˆ’11.5 Â°C (11.3 Â°F)
I though it was
32 - 28 light frost
28 - 26 medium frost
26 - 24 hard frost
24 - ....... hard freeze
Frost can occur when general air temps are above 32F, so the above list is somewhat misleading. The reason for this is that the air radiates heat more slowly than surfaces (including plants), so in certain conditions (mainly clear, calm nights when heat can radiate into the atmosphere more easily) the plant leaves can be colder than the air around it.
Any extended temps below freezing will be an issue for non-cold-hardy plants, especially once you get below 28F, as the water in the plant cells can take a pretty good beating at that point.