How to get a Jump on Vegetable Gardening without Building a Greenhouse

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So you think you’d like a greenhouse

Ah, the greenhouse! Few gardeners garden for long before they begin to consider the advantages of having a greenhouse on the property. But the fact is, not everyone has the room for a greenhouse, or the need for an outbuilding of that size. In some cases economics may forbid a project on the scale of a greenhouse. How then, to get a jump on the growing season?

Green House

Green House (Photo:

A cold frame

A time honored alternative to a greenhouse is the cold frame. This is essentially a low slung structure, usually square or rectangular, with a glass or Mylar roof. Commercially constructed cold frames, many in kit form can be widely purchased, most for a surprisingly low price. When fitted out with a few simple accessories like a small thermostat driven radiant heater and minimum/maximum thermometer these small structures mimic the function of their larger greenhouse cousins very well.

Here are two simple cold frames that anyone can construct, with minimal tools or carpentry skills:

Hay bale cold frames

Nothing can be simpler! Simply buy inexpensive bales of hay or straw and arrange these in a square or rectangle of such dimensions that all the plants within can be easily worked from outside of the frame. A deeper bed can be created simply by laying up two courses of bales, just as one would lay bricks.

Two by fours or any available pieces of scrap lumber are cut and nailed together to form a frame that will sit on top of the bales. Mylar plastic is then stapled or fastened with short roofing nails or tacks to this frame, to form the roof or lid of the cold frame. Depending on climate it is probably desirable to add the thermometer and heater mentioned earlier.

On windy days it is always a good idea to weigh, tie or otherwise secure the roof to the hay bales, should it blow off the young plants within could be lost.

A quick plywood cold frame

This makes a simple yet enjoyable winter project that can be used and re-used for years to come. All that is needed are two 4’ x 8’ sheets of inexpensive plyscore, or exterior grade plywood if you do not mind spending just a bit more money. Cut the first sheet lengthwise into two pieces, so that you have a piece 12” x 8’ and a piece 36” x 8’. These, after one further cut has been made will become the front and back pieces of the frame.

With the second piece, measure 12” from the bottom on the 4’ long side, and 36” from the bottom on the opposite end of the sheet, again measuring along the 4’ length. Run a straight line on the diagonal from the 12” mark to the 36” mark and cut along that line. This will give you two symmetrical pieces that will attach to the previously cut 12” and 36” x 8’ rectangular pieces to from a vertically slanted rectangle, which is the cold frame.

Note: If you plan to leave spaces among the plants so that you can step into the cold frame to work, no further cuts are required, and the dimensions of the frame can remain at 8’ x 8’. If however you wish to work only from the outside then cut the rectangular 12” x 8’ and 36” x 8’ panels to a maximum length of 5’, which is a bed size as large as all but the tallest of folks can comfortably work in.

Whatever the final dimensions of the frame are, make a scrap wood or 2” x 4” frame as with the hay bale model, and cover with Mylar, to form the roof.

To get maximum life out of the cold frame, paint the plywood with several coats of outdoor paint, preferable dark paint to enhance heating by the sun.

The cold frame may be tacked together with nails, not driven all the way home so that they may be pulled out easily when it is time to take the cold frame down. Better still is to employ snaps or other fasteners – simple hook and eye latches, for example – so that the frame can be taken apart and re-erected many, many times.

Add the thermometer and heater, and you are ready to set your plants out!

Simple solutions

As can be readily seen, the answer to a simple and inexpensive greenhouse alternative can be simple in the extreme. Make no mistake however; the time honored cold frame has been nurturing young plants and extending growing seasons for centuries. It can do so for your plants today.

Mac Pike

Mac writes about gardening, cultivation, and sometimes produces uniquely humorous articles from Zone 6. Mac enjoys finding new and interesting ways to accomplish growing and competing with bears in wooded Northern New Jersey.

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