Rethinking Cold-Frames (part 2)

Greens all winter long - that's dream of the cold-frame. But is that the reality? And if not, what role can they play in a garden?

In last week’s article I discussed the pros and cons of cold-frames. The outcome of that examination was the following:

• (Pros) They are good for getting an early start; accelerating growth-rates during early season; getting transplants started; and for helping some plants survive the winter.

• (Cons) They don’t offer much growing space; plants in them really don’t grow much during the winter; they don’t really provide “food all winter long”; they need to be vented or plants die; and they provide a wonderful habitat and food source for garden rodents.

Based on the pros and cons listed above, I think the best way to use them is as a temporary microclimate to be: (1) brought into the garden in late winter/early spring for some crops to get them going; (2) stored away as soon as they are no longer needed by the plants; and, (3) brought back into the garden in fall to extend the season, or even to protect some things over the winter. In today’s article I will to discuss some design considerations that make them cheaper to build and more versatile in their use.

What is a cold-frame?

A cold-frame is a microclimate, which, as defined in a previous article - is any given space where the climate conditions (temperature, humidity, wind, etc.) are different from the larger area in which that space is located. While they tend to be presented as solid, permanent, heavy wooden boxes - there is no reason they can’t be light-weight, non-permanent, and even foldable.

1. Small rectangular dome

Some tough greens, like spinach and lettuce, can germinate and even grow when the soil is barely thawed. A small dome like the 3’x3’ example in the picture below positioned in March, or even late February sometimes, can thaw out the soil, and raise its temperature enough for germination of tough greens in late March. A little later it can be used for things like kale and Swiss chard. Since these greens don’t mind the cold, the little dome doesn’t have to be that high, and that’s good because that makes it lighter and easy to store.