I really feel stupid asking this question

[Palmy]

Im just curious at what temp does frost start to occur on the grass? What about trees? If its on the grass is it on the trees? I would think not because the cold air sinks. Why is it I see no frost on trees and palms yet on the grass. Im full of questions, also when you see frost on the ground, like a hard frost, what temp does that occur? I have never seen frost on the trees here. Yet I see it on the grass and sometimes everywhere on the ground. And why on the roof too? Lol, sorry bout all the questions. If you can answer them, I would be happy because on most clear nigths in the winter, there is usually frost on the grass and roof.

[SunnyFl]

Hi Palmy,

There's nothing stupid about your questions - they're good ones.  I can't answer all of them because we don't have much frost here, but here's what I do know:

Frost is the process of water vapor freezing.  It can form even when the temps are in the mid to upper 30s; however the surface that the frost forms on will be 32F or lower, even if the air temp isn't.

You will sometimes see frost on the ground and not on the trees or other plants because the temp at ground level is colder (as you mentioned, cold air sinks).   So, if you're also seeing the frost on the roof, its surface temp is at or below freezing as well.

In other cases, a heavy frost might settle on other plants, if their temperature is cold enough.  For many palms, it's frost that is the real killer; a palm that might withstand 27F without a frost might not fare so well if frost is involved.  This is why "canopy" is so important for palms grown a little out of their zone - the tree canopy above the palm keeps the temp a bit warmer so frost doesn't form on it.

Hope this helps!

[spockvr6]

(SunnyFl @ Jul. 07 2006,08:01)

QUOTE

 I can't answer all of them because we don't have much frost here,

We still have too much for my liking!

[Palmy]

Thanks. Now I understand.

[SunnyFl]

(spockvr6 @ Jul. 07 2006,09:21)

QUOTE

(SunnyFl @ Jul. 07 2006,08:01)

QUOTE

 I can't answer all of them because we don't have much frost here,

We still have too much for my liking!

This is because you live in Zone 9  

J/K - I know that last valentine's day was a real bummer in most of the state.  We just lucked out here.

[spockvr6]

(SunnyFl @ Jul. 07 2006,19:23)

QUOTE

(spockvr6 @ Jul. 07 2006,09:21)

QUOTE

(SunnyFl @ Jul. 07 2006,08:01)

QUOTE

 I can't answer all of them because we don't have much frost here,

We still have too much for my liking!

This is because you live in Zone 9  

J/K - I know that last valentine's day was a real bummer in most of the state.  We just lucked out here.

If I live in Zone 9...you do too...hehehehhehee.  I know I joke about saying I live in the "north Pinellas tundra", but its really not all that different up here than most other areas of Pinellas.

But yeah....most of the Tampa Bay area did luck out on Feb 14th.  We could have gotten far worse.   Even with this one night event factored in, it was still an above average winter as far as low temps go.

[SunnyFl]

(spockvr6 @ Jul. 07 2006,21:56)

QUOTE

If I live in Zone 9...you do too...hehehehhehee.

Shhhhhh - don't say that so loudly.....

You'll scare every plant in my (zone 10) garden hehe.

True, we do have some nail-biting in the winter months, but unfortunately, the bigger threat to our palms (and other living things) comes around this time of year.  Till Nov. 30th.  

[spockvr6]

(SunnyFl @ Jul. 07 2006,23:04)

QUOTE

(spockvr6 @ Jul. 07 2006,21:56)

QUOTE

If I live in Zone 9...you do too...hehehehhehee.

Shhhhhh - don't say that so loudly.....

You'll scare every plant in my (zone 10) garden hehe.

Id say a good 9a night will take out half my yard as well    But, thats why the other half is there.  Unfortunately, the half that will get wiped out is the interesting half

[SeanK]

Given the right conditions, frost can be seen around 37°F (3.5°C).