First Frost

This past weekend brought the first frost to the farm. The first night the forecast was for 30 degrees and they hit it bullseye. Forecasts are tricky here in the mountains where temps can vary depending on which mountain or valley is yours and where you are situated on the slope.

When I looked out the window I was surprised there was no silver frost on the ground and no blackened leaves on the tomatoes even though the thermometer read a flat three-oh at sunrise. It must have been breezy in the night. A flow of air can keep the frost from setting on leaves and doing damage. I’ve read that peach and citrus orchards down south might set up giant fans to blow air around if an unseasonable frost threatens.

Situating your garden on a slope can help with frost damage as the air flows down the slope at night. Frost usually settles heaviest at the lowest point, a frost pocket. A farmer friend of mine who grew on the valley floor of Celo told me how another farmer not even a quarter mile up the slope of the mountain behind him, could go a couple of weeks frost-free after my friend’s field was  already winter killed. Two weeks is a long time if you are racing the freeze to get a crop ripened. This was due to the difference in their microclimates. The coldest air flowed down the slopes and gathered on the valley floor, leaving the lower slope slightly warmer by comparison — much like the coldest water sinks to the bottom of a lake. The top of the mountain isn’t the warmest though given the wind and elevation.

That warmer air band on the side of mountain or slope is known as the thermal zone.  It’s a great place for a garden or farm to be located. Five Apple is not exactly in the thermal zone of our mountain but nearer (though not completely in) the valley floor. On walks up the mountain behind us in winter there’s an area that is noticeably warmer than above and below it. While no one gardens it now, the oldest cabin on the mountain happens to be located right there.

I suspect folks from that time were more astute to these things as it made the difference between ample food and not, a more comfortable cabin or a colder one.  I lived in a 1929 house in Asheville which had never had an air conditioner. I noticed the eaves and roof overhang were deeper than I was used to seeing. The first summer I found out that just as the season got warm, the sun would be high enough in the sky for the eaves to intercept the light and not shine directly into the rooms on the south side of the house. Someone knew just how long to make the eaves so that they would block the sun by early summer but allow the sun to reach deep into the rooms late fall through spring. That is when paying attention emerges as beauty to me.

The second night at Five Apple of 30 degree forecast turned to 28 degrees without a breath of wind. The tomato leaves blackened, signaling it will be a new calendar year the next time I bite into a warm cherry tomato right there in the garden. Indian summer is over and Autumn is glowing in colors everywhere. As Mary Oliver describes, ‘the trees are turning their bodies into pillars of light.’   Autumn is always in motion—moving  steadily towards winter. It’s bittersweet. But first frost brings on writing season for me and I’m looking forward to posting again.

I know I mention microclimates a lot in this blog. On your land (or even in a small yard) there are colder and warmer spots, windier and more sheltered spots, there may also be thermal zones and frost pockets. If you know where they are then it helps you better locate homes for plants or trees that need a little protection or need a little extra chill. For example, in some circumstances a spot where the soil stays frozen or snow covered longer than the surrounding ground can be handy if you are trying to convince a plant to not bloom until a little later in the spring — when the buds are less like to get nipped by cold. That same cold spot can be a killer if it’s a plant or tree that barely hardy in your planting zone.

The season to watch carefully and observe the microclimates of your land is here. Frosts (and snows) are great times to wander about and get to know your land more deeply. Maybe start a little notebook you can jot what is going on that day or week in your garden and surrounds? Entries can be simple like — First hard frost of the season at Five Apple Farm. Blue Ridge Mountains, south-facing slope*, 3000 feet: October 17, 2015. First killing frost: October 18, 2015.

*the aspect of a slope — which direction it faces — vividly affects what grows there. Wiki has some great photos illustrating this: https://en.wikipedia.org/wiki/Aspect_(geography)  I love to compare the forest composition of north-facing and south-facing slopes while out on walks. This is type of thing geeky types may ponder on hikes… The most dramatic difference I’ve ever seen was in the Ouachita mountains in Arkansas https://en.wikipedia.org/wiki/Ouachita_Mountains which run east-west making them very unique vs the more north-south orientation of the ridges here and in most places. I think that’s what makes the people of the Ouachitas so unique and special—shout out to Charity though she hardly ever reads blogs!   🙂