It is the dream of many gardeners, especially those in northern climates, to have a greenhouse. Unfortunately, for a home gardener, it is almost impossible to justify economically. There is no way it’s going to pay for itself, unless you build the frame from salvaged materials and never heat it. Under those conditions, of course, it is simply a large, aboveground cold frame, or a walk-in cloche.
The only true greenhouse that is really justifiable on ecological grounds is a solar greenhouse, because it practically heats itself. The production cycle of fossil fuels and electricity is inherently detrimental to the environment; to use them for heating a personal greenhouse is irresponsible when simple design features that capture and store the sun’s heat can make it an ecologically positive structure, a way to lessen your dependence on food grown far away and shipped long distances at great energy cost. Though freestanding greenhouses are technically better, because they get more light, I would nonetheless opt for one that is attached to the south side of the house or garage. By building a solar greenhouse attached to your own house, you’ll not only enjoy the benefits of growing plants and crops; you’ll actually help heat your house. On this basis a greenhouse becomes a great investment both for yourself and for the world.
For the details of greenhouse design and management see: (link). Suffice it to say that you could easily grow enough seedlings for an average-sized home garden in a little 6X8-foot greenhouse attached to the house, say, outside a set of patio doors. For a larger garden, or if you want to grow food in it, an 824-four-foot greenhouse is a very good size; it is an efficient shape, and fits in well architecturally with most houses. You’ll find references in the Bibliography to some excellent books on the subject.
A cold frame, however, is within the reach of almost every gardener’s budget. In fact, you can often build a respectable one for nothing more than the cost of your time. Old storm windows, some leftover lumber, and a course (layer) or two of cinder blocks will make a really first-rate, permanent frame. For temporary use, even simpler materials will suffice, like a rectangle of hay bales with an old window laid on top.
My grandfather’s cold frame was a three-sided cinder block affair partly sunk into the ground with a deep berm of soil insulating the walls. The covering was multipanes of single-glazed fixed windows of the type used for barns
He made the front wall two blocks high, but flush with the existing ground level, while the back wall was four blocks high, so that the pitch of the sash from back to front was steep enough to provide for runoff.
While the materials have changed since my grandfather’s time—rigid insulating acrylic panels, which have a much stronger insulating effect than glass, come in wider sheets, and are almost impossible to break are an improvement as well as a replacement for the old glass sash—the principles of construction are still good. Placement of the cold frame should take into account not only the orientation of the garden—since obviously it should face south, or at least nearly so in the North—but it should also be in a convenient location. Line the outside of the block walls with landscape fabric to keep weed roots in the rear wall berm from working their way through; foam insulation outside the liner will turn the cement blocks into an effective solar heat storage mass. For even more thermal mass, drums filled with water and painted black could be placed inside the cold frame. With these additions, the gardener will have nearly a year-round gardening frame, even where winter temperatures regularly drop below zero.
One other major structure you’ll want in your garden is a shed for storage of tools, and to work in when the weather is uncooperative. Traditionally, the potting shed is to the gardener what the workshop is to the woodworker, and while the gardener generally works at his or her craft outdoors, there is a need for an indoor workspace.
The requirements of a potting shed are few, and in many situations may be met by using existing buildings; but where construction of a building for the purpose is necessary or desirable, either on its own or in combination with a greenhouse and/or cold frames, a few basic considerations should be taken into account.
First, since the potting shed is a place to store tools, there should be sufficient space to hang all your hand tools well up off the ground. Simple nails in the wall will suffice, but the more organized you are the more enjoyable your time in the garden will be, and the less of it will be spent cursing a lost tool. In addition to the hand tools, there should be room for any power equipment you own, the tool-cleaning tub of oily sand described in Chapter 3, and any consumable supplies like potting soil, pots, and such. Fertilizers and pest controls, even organic ones, should be kept in a latched cupboard or room to protect curious kids and animals.
Second, the potting shed should provide enough space for the gardener to sit comfortably at a workbench to do the tasks that can be done indoors. This includes, but is obviously not limited to, the sharpening and oiling of tools, plus the sowing, pricking out, and potting on of seedlings. A well-designed shed need be no larger than, say, six feet by eight feet. It could adjoin another building, whose exterior wall might suffice for hanging tools; then even less space will do. Whatever its size, though, a tool or potting shed does not need to be fancy; we are simply trying to get in out of the weather, not build an edifice that will stand with the pyramids.
Our last aspect of basic garden design is compost piles. While many gardeners—my grandfather and I included—start out building their piles on any piece of open ground, you should at least consider making a permanent composting area part of the overall garden plan. If you do, take mind of the fact that compost piles need a lot of air. Any combination of materials and methods that expose the pile to the air, while holding it in place, will work well. Well-designed aerobic compost bins can be bought ready-made from several different companies, but the capacity of most of these is only a cubic yard or so. For larger gardens, you’re better off constructing a series of bins, so that multiple piles can be created and matured in succession.
Suitable materials include metal fencing; wood, including salvaged trucking pallets (portable platforms for moving materials); and concrete blocks. The metal fence should be the inexpensive type that comes in twenty-five-foot rolls “woven” into a grid of rectangles. It is formed into one or more upright circles and held erect by a couple of metal posts. Or a mesh bin could be made from sections of heavy-duty concrete reinforcing steel mesh welded to rectangles of channel iron, which could be fastened vertically at the corners. A bin made from salvaged pallets works the same way, though, and is certainly cheaper. The problem with all of these bin designs, however, is that the sides are of a fixed height, and the materials to be composted will have to be lifted over it. With a bit of creative siting this problem might be overcome, but in most cases a simpler solution is to make the bin so its walls can be built up as the pile itself grows.
One way is to make the retaining walls from cinder blocks laid so the holes are horizontal. They are stacked in the same fashion as for building the coldframe walls, that is, butted at the corners for stability, yet the horizontal orientation of the holes allows air into the pile along the whole wall. Don’t build this wall much higher than three courses, or the outward pressure of the pile might cause it to fall over and you’ll have a mess on your hands. The pile can be heaped considerably higher, though.
The composting area should be central to the garden, so the distance that materials will need to be transported is minimized. Ideally, the center of the four-square garden design could consist of a small potting shed/greenhouse/cold frame with compost piles arrayed around it under the eaves of a large overhang. This would be the most efficient possible setup.
Our own garden can serve as an example again. We put the composting area at the uphill end of the garden, and cut into the hill a bit so that the retaining wall used to form the driveway turnaround could serve as the rear wall of the bins. This makes movement of manure and other composting materials from around the property simple: To unload onto the piles we just back the truck into the turnaround and pull the materials from the back of the truck right onto the piles.