Attached to our home, and opening into the greenhouse, is the 11-foot wide by 552-foot long annex-workroom.

The greenhouse itself is small, about 9M feet wide by 12 feet long. It was built to allow for expansion. The heating system was therefore made larger and more expensive than was necessary for the original under-glass setup.

But as I mentioned earlier, the greenhouse was soon doubled in size, which put the oversized heating system to full use.

The greenhouse is built out from the west side of the house, so its long sides face north and south.

Some of the plants I grow for profit are sun-lovers, others thrive in shade or semi-shade. Those needing the most sun are grown on the south side. My selection of plants is varied, yet they all do well in daytime temperatures of 70 to 75 degrees F., with the usual night drop to 60 or 65 degrees. Indeed it is amazing what different kinds of plants can be accommodated in the same house.

Building My Greenhouse

All buildings in northern zones must have footings (foundation extensions) which extend below the frost line. Greenhouses are no exception. In my area, footings must be dug to a depth of 3? feet so frost will not heave the foundation and crack the greenhouse glass.

We dug and poured the footings ourselves (a measure of economy), but we hired a cement contractor to lay the actual foundation and the greenhouse walk or aisle. The foundation is made of cement blocks; it is 5 cement blocks high and 6 long. The walk is made of cement slabs. This work and the materials cost $285.00 and the job was finished in 1 day. Within 2 days the cement had set and we went on with the rest of the construction.

The actual details of fastening supports and cross-pieces, installing doors, ventilators, and so forth are not relevant here. In the first place, they would require endless pages of text and diagrams?and such data are easily obtained from any number of commercial greenhouse construction sources.

Also, there is no one "best" way to build a home greenhouse?there are dozens! The construction as well as the type will depend on the requirements of your climate and what you desire (and can afford).

Incidentally, construction guides are available from lumber firms as well as greenhouse builders. I will offer, how ever, certain points of information that are generally helpful, whether you build your own greenhouse or have it built by a construction firm.

For instance, we chose redwood, sturdy and rot-resistant, for the greenhouse framework. It has proved to be a wise choice. Trenglaze, a non-hardening putty, was used to bed and seal the glass panes (called "lights" in the trade). We used non-rusting brass screws throughout. Also, we used double-strength greenhouse glass.

This costs about 20 per cent more than single strength, but it is many times more durable. In the 4 years I have had this greenhouse not a single pane has broken or cracked. The lights, cut to fit by the manufacturer, measure 20 inches wide. On the roof the lower ones are 20 by 42 inches. These are larger than many greenhouse builders use, but they mean much less construction work, admit maximum light to the plants, and minimize drafts. A layer of pea rock covers the ground flanking the walks.

Finally, we painted the outside cement blocks pale green, the framework white, to blend with our green-and-white stucco home.

For Maximum Space

The first year the greenhouse was a two-bench type with 3-foot wide wooden benches running the length on either side of the center aisle. As orders increased, we needed more growing space. Accordingly, we installed a double-deck bench system. This provided a larger growing area and also helped with the shading problem.

A full length bench about 2 feet wide, with legs 2 feet high, was placed on top of each of the two original benches. Three-inch deep galvanized metal trays were set into each of these top benches to prevent dripping. While these top-level benches greatly increased plant space, they also cut off some of the light from the first-level benches.

However, this turned into the traditional blessing in disguise, for the partly shaded area of the lower-level benches proved ideal for African violets. And the plant space close to the glass along the south side on the first-level benches, and all of the space on the top decks, still received full sun. The increased bench space also reduced crowding. Plants must not be crowded if they are to be healthy and grow symmetrically.

A free circulation of air is always necessary to prevent fungus and other troubles.

In your greenhouse, you may work out the use of space a little or a lot differently. It always depends on what you want to grow and also on the limitations your particular site may have as to light. It's usually a good idea to solve some of the space problems gradually as experience indicates.

On the south-side, top-deck bench, I place potted seedlings of gloxinias (hybrids from crosses involving gloxinias and rechsteinerias). Here, too, I place starting tubers as well as plants which have finished flowering and are ripening seeds. On the north-side top deck, I set flats of episcias and rooted glox-inera cuttings. Trailers such as aeschynanthus, columnea, cissus, ceropegia (rosary vine), and plectranthus take up little space and do a good job of covering the sides of the galvanized tray.

On the lowest bench, close to the windows on the south side, I have slipper gloxinias and their South American relatives, the red- and orange-flowered rechsteinerias, as well as more gloxinias, a few species amaryllis and pink polka-dot plants. The rest of the first-level bench area, shaded by the top deck, is devoted to African violets. Additional space is gained by hanging baskets from the ceiling. I plant kohleria, columnea, and some orchids in these. I think hanging baskets always make a greenhouse more attractive.

My own greenhouse'a 12-footer plus workroom-annex?paid for itself in 9 months. I will give you a few of the salient points of its construction, but mostly I'll describe operation, for it has been successful enough to warrant expansion to twice the size?and after only 4 years. And I will tell you something about some other successful ventures which will give you still more ideas about building and operating your own greenhouse.