March 8th was an exciting day!
Inside the first low profile marmot and cold protection frame:
Signs of life...
An update on the lids: I decided that slipping clear plastic bags over them was not going to work. Too much moisture was condensing inside the bags, which would rot the lids, and the bags tended to flop around in the wind and drag down too low, almost to the soil, underneath. The above photo shows my large frame (8x6') with the lids revised.
I pinned plastic to the underside of the lids, up against the hardware cloth, by screwing on thin strips leftover from ripping slab wood. The strips hold the plastic to the inside of the frames.
Then I added a rib down the middle to help support the underside of the plastic once the lid was placed on the frames again.
Here's how they look placed back on the frames. Much neater, too!
I also added hinges using eye-bolts and fencing staples with a piece of twisted wire in between. These will help keep the lids on during windy days, and will make access easier. The wire can be removed if I want to take the lids completely off while working.
So far this marmot and cold weather solution is really working well! I can't wait to build more frames.
Update: We've been eating salads from this frame throughout April and May, the earliest greens yet. It was an exceptionally warm spring, but these were by far ahead of other greens not protected from the elements and the marmots.