Friday, January 22, 2010

Heating Up the Cold Frame

The cold frame has been outside for about a week now and we have had two sunny days recently. I use a maximum-minimum thermometer and a soil thermometer to record the effect of the cold frame. Most interesting is that the soil inside the frame, except near the front edge where the sunshine doesn't reach, is no longer frozen.

There is no doubt that the sun warms up the air and the soil inside the cold frame. On January 21st, when the high daytime temperature (according to the newspaper) was 32 degrees, the temperature inside reached 64 degrees. It was a bright sunny day. The next day was another mostly clear sunny day and the temperature got up to 61 degrees and the soil temperature (taken in the area that the sun reached) was 46 degrees, although the outside temperature high was 36 degrees.

After I put the cold frame outside I added insulation that I bungee cord over the glass in the afternoon when the sun no longer reaches the cold frame.
Two nights ago the outside temperature dropped to 14 degrees but the lowest temperature inside the cold frame was 30 degrees. Last night the outside temperature was 12 degrees but the lowest temperature inside the cold frame was 29 degrees and the soil temperature in the morning before the sun struck the cold frame glass was 36 degrees.

What these mean is that, on those two clear sunny days, the temperature inside the cold frame got up to 25 to 30 degrees higher than the outside air temperature. At night the temperature dropped below freezing but was about 16 degrees above the outside air temperature. The soil temperature remained above freezing although it dropped about 10 degrees.

We have three more warm (but not necessarily sunny) days coming up (projected highs in the mid 30s to low 40s) followed by a return to much colder weather (highs in the low twenties and lows around 10 degrees). I may move a few of the mache and claytonia seedlings that I grew as an experiment into the cold frame tomorrow to see if they can survive the colder weather. Do I leave the insulation on all day if it is going to be cloudy? Do they need sunlight or warmth more?

Thursday, January 14, 2010

Keeping Busy in the Winter

What is that object sitting in the midst of the snow in garden bed #4?
Today is January 14th. Snow covers the garden. After all, this is Syracuse. I can't prepare the soil, plant vegetables, fertilize plants, or harvest produce.
The seed catalogs have been here for over a month and the seed orders have already been placed and some have arrived.
The plan for this year's garden is made. What will be grown and where things will be planted has been decided.
Is it time to relax and read? Some.
But when it is impossible to work in the garden it may be time to work in the cellar. The object is my first attempt at a cold frame. I just put it out in the snow today because we are supposed to have sunny weather and temperatures above freezing for the next four or five days. My hope is that this weather will warm up the soil inside the cold frame so that soon after the beginning of February I can plant the little spinach and corn mache seedlings that are growing in the cellar. The magic date is supposed to be around February 8th when the daylight will have increased to ten hours.
Here is the cold frame up close.
Except for the screws that hold it together, the insulation hidden inside and the insulation strip that lies under the edge of the glass, it is made from materials that I (or my son, Greg) collected or that have been in the cellar for some time. When I see large storm door windows by the side of the road I grab them. This one is somewhat small, about 26" by 29". The frame is made from 3/4" pine some of which was a neighbor's shelving unit that found itself at the curb. The sides are screwed into halves of pieces of 2" by 4" at the corners. I cut up pieces of our old cedar fence about 1 1/2" wide and nailed them to the bottom of the sides so that the initial rot over time will be of the replaceable cedar pieces and not the pine sides and to hold the insulation. I cut one inch foam insulation and added it to each side covered with black plastic stapled to hold the insulation in place and absorb more sunlight. Right now the cold frame sits on a piece of black plastic that hopefully will absorb heat from the sun and melt the thin layer of snow under the cold frame and warm the soil that is below that. I was planning to remove the black plastic but I could just make slits and plant through it. Since the glass sits on 3/4" pieces of wood screwed about half an inch below the top of the cold frame I placed a metal corner brace under the glass when I put the glass in so that I have a way to lift the glass when I need to get inside to plant, water, etc. The string was added as a back-up means of lifting the glass when I forget to put the corner brace back in place.
The last step will be to cut a piece of foam insulation the size of the glass to bungee cord on top of the glass when it is supposed to get really cold. I may also add a piece of row cover over the plants inside to provide additional protection. I have to purchase a maximum-minimum thermometer to put inside in order to see what the range of temperature is.