Cold Frame # 2

Unbelievably good timing. The drywaller got behind schedule in the workshop and we weren't ready for painting this past weekend, so the cold frame got moved up as the weekend project. (Plus the drywaller said he'd prime the whole thing for $100 and that will save a weekend's worth of work next weekend, so we said, uh, yeah!)

And... Voila!

The base box (below) is constructed of 2x12 boards salvaged from the property, lined with 2" foam board (left over from insulating the addition). (You can see the insulation installed along one of the base board walls.) That base box was placed in a trench so that about 3" is above ground on the uphill side.

On top of that is another identical box made of new 2x12 boards. Then a 2x12 riser (back) leans on two 2x12 triangles (end walls) to support two fabulous Habitat for Humanity Restore double-pane windows, $5 each. The windows are 42" across and 51" tall for a total cold frame size of approximate 4' by 7' (28 square feet.) (The white framed one, from the same source for the same price, is headed to a friends' house for her cold frame.)

We used gorilla glue to mount a foam window insulating gasket around the box. It's not a perfect seal yet, so work remains there.

I bought what appears to be a nice value - a wireless "Weather Thermometer" made by AcuRite ($15 at Lowes). The outdoor sensor is hung on the inside of the south wall of the cold frame (so it will not be in direct sunlight) and the base unit that reports the temperature of that sensor is either inside where I can keep an eye on it, or as pictured below, outside where it monitors the true outdoor temperature. So on this first day with a closed top, and soil that is still quite cold, the outdoor temperature is 60 and the box temperature is 74  (with a high of 75 and a low of 51 - when I installed the thermometer in the morning.) (Made me think about installing an automatic vent opener like this.)

The soil at the site was better than average for our yard, but a little stony, and with some pretty serious subsoil clay (red mottles and everything.) I decided to keep it, but added a significant amount of peat moss to help keep a loose structure, and then a full dose (4.5 cups for this 28 square foot bed) of Organic Garden-tone Herb&Vegetable Food (3-4-4). If I can get the timing right mid summer, or next winter, I will try to add a good load of compost.

I already posted about my seed starting enthusiasm. Now I'm using the cold frame to help those seeds get good sunlight since I still haven't invested in grow lights. So far, even with gray days, it seems to have been enough help to prevent them from getting embarrassingly leggy. The seeds are all still in their starting trays. I'm not sure the soil in the cold frame is warm enough for germination, and until it warms up I'm not sure I can count on the box staying above freezing, so I am a little nervous about direct seeding in there, although given the cost of seed, it's a relatively low risk venture.)

Overall, and as always, I wish we had gotten an earlier start. But with these cold frames deployed, it will certainly be possible to plant 2-3 inch diameter lettuce starts by the middle of February, and to be harvesting lettuce by now. This permanent installation is going to be full of food through the shoulder seasons and potentially the winter for years to come.