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With apologies for the long delay, here's the latest --- and last --- word on the Taj Mahal.
Quite a bit has happened in five years: We've survived the gale force winds of Hurricane Isabel; we've installed high intensity discharge (HID) lighting; we've rebuilt the raised beds; and, best of all, we've been eating excellent tomatoes out of the greenhouse in wintertime!
One of the less exciting happenings, however, has been the need to replace, three times, the motor that operates the ridge vent. The first one lasted about two and a half years; the second one I installed incorrectly; the third one lasted about nine months, and the present one has been okay for over a year. Don't quite know what the problem is, but it's very annoying!
Apart from that, the greenhouse has done remarkably well. It sits empty during the summer, when everything is growing outside. In September, I start the cukes and tomatoes destined for winter growing, and toward the end of the month, the gh gets its annual scrub and, if it's needed, a paint job. The soil in the raised bed gets compost and fertilizer mixed in, and the cukes and tomatoes are transplanted in October. Peas, carrots, and salad greens are sown by the end of October, and from then on it's just routine maintenance. I usually get the first cucumbers by the end of November, and they continue yielding bountifully into March. I've stuck with the same variety, Glacier, which is delicious and yields abundantly.
The only major pest problem I've encountered is spider mites, and I keep them under control with a pyrethrum bomb about every five or six weeks. |
The Tomato Story
At the end of Part 16 I left you with the disappointment of discovering that the greenhouse tomatoes I'd grown that year (winter/spring of 2002) were totally tasteless. The next year I tried a different variety of greenhous tomato, Cabernet (right), and a cherry tomato, Juliet (below), both of which grew well and were much tastier than their predecessors. The third year I stayed with Cabernet, but also decided to try a "regular" tomato (not a "greenhouse variety"), Supersonic Hybrid, which, to my surprise, grew perfectly well and yielded far tastier fruits than I'd had so far; the secret, I think, was installing the HID light, about which more below. After that, I didn't bother with greenhouse varieties any more, and grow heirlooms (Mexico and Anna Russian do particularly well). |
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I start picking them in mid-January, and still have a couple waiting to be picked now in early July. Once it starts getting into the nineties in the greenhouse, the plants set fewer fruits and production slows down to the point where I stop giving them away! But there are about a dozen green tomatoes on the outdoor vines now, so I won't be tomatoless for long. |
The HID Lights
I installed a Sun System VII, which contains both a metal halide (MH) bulb and a high-pressure sodium (HPS) bulb. Each of these emits light of a slightly different spectrum: The HPS bulb gives off a yellowish light that promotes flowering (and hence fruit set), while light from the MH bulb encourages growth and photosynthesis. Obviously, having both kinds of bulbs gives the best of both worlds. I installed the reflector containing the bulbs on a motor that moves the lights back and forth along a rail mounted to the roof of the greenhouse, distributing light to the whole raised bed area. Since the contraption has three cables coming from it (one for each bulb and one for the motor), and since it moves back and forth, some method had to be devised to keep the cables from getting tangled up with each other, the plants, and everything else; the photos to the right and below show this arrangement.
The stovepipe-like thingy sticking out on either side helps dissipate the considerable heat ---very welcome in winter! --- generated by these bulbs. |
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The three cables (two from light bulbs and one from motor) are bundled together and at two points along their length are attached to swivels that run freely along supporting wires installed parallel to the light rail. And yes, this whole business was a bitch, from beginning to end, to set up! First of all, the light rail has to be level, but is attached to roof bars (rafters) that are angled; we bent suspension brackets for this by hand, from aluminum stock. |
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Secondly, the rail came in three pieces, which had to be butted together precisely end-to-end, to allow the motor to roll smoothly across the seams. And finally, it took endless fiddling to get the lengths of the cable loops exactly right, so that the cables didn't entangle anything, yet allowed the motor a full run of the rail.
The HID bulbs connected to a large, HEAVY ballast, which burned out after |
| two years, and was replaced by two separate, smaller and lighter electronic ballasts. And finally, the whole shebang is connected to a timer that automatically turns the lights on and off, and starts/stops the motor at set times. This was an expensive and time-consuming addition, but it was worth it in the long run. |
Rebuilding the raised bed
There were two problems with the original raised bed I built: First, it was very difficult to reach all parts of it; and, because of the low angle of the sun in winter, I couldn't grow things near the kneewall since it was always shady there. So, last summer I took the plunge and completely rebuilt the raised bed, moving it 18" away from the kneewall . I lost a bit of square footage, but I think I gained in usable area since now I can work the bed from both sides. |
The photo on the right shows the rebuilt beds, one 18" high, the other, 8". The original bed was lined with plastic, but this time I was smarter and used a membrane roof flashing material. I'm not sure if it's just heavy vinyl or EPDM, but it was so much easier to do a neat job than with flimsy 6 mil sheeting. A single piece runs all around the bed, and where the ends overlap they are sealed with pond liner seaming tape.
As shown in the photo below, the upper edge of the flashing is bent over the top of the 2"x10" forming the side of the bed, and secured with roofing nails through laths salvaged from an old snow fence.
In the photo on the right, you can see that the HID light on its light rail is no longer centered over the growing area, and so it had to be moved to the left, with considerable swearing.... The final step was laying a strip of the rubber matting (which is now carried by Sam's Club) down the new walkway on the right. |
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I'm totally happy with this new arrangement, which makes much more sense! |
Adding insulation
In a previous section I mentioned the difficulty of keeping the temperature in the greenhouse from getting too high, and I've installed some insulation to help this problem, which also helps keep the greenhouse warm in wintertime. The material consists of plastic bubbles sandwiched between two layers of reflective foil, and is stiff enough to stand on its own. I cut pieces the same size as the polycarbonate panels and insulated the whole northeast side (which received no sunlight anyway, because of the tool shed), and the upper half of the northwest gable. |
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Most recently, I switched the original door around, so that it now opens to the inside, and added a full screen door, which greatly improves ventilation.
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And now --- August of 2007 --- I declare the Taj Mahal Greenhouse finished!
My wallet is lighter, but my heart is fuller, and that's a good exchange.
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