We're attached to our greenhouse.
I read that an attached greenhouse should be twice as long as it is wide, and for efficient solar collection and sufficient growing space, not less than eight feet, or wider than 10 feet. Why limit yourself, we thought? We built ours 38 x 13 feet. The "extra" three feet in width does not receive direct sunlight, so we use it for storage and a sitting area. Everything else is for gardening, storage, and an entryway leading into the house.
The first priority for any greenhouse is a southern exposure to maximize sunlight. One advantage to a freestanding greenhouse is that it is not limited by the home configuration and can be oriented exactly south. Fortunately, our house runs east and west so this wasn't a problem. However, a large tree--a beautiful, food-providing bird shelter--was smack-dab in the way. It was a tough decision, but we are off-grid with solar panels that must not be shaded. The tree had to come down. Only the stump remains, but the birds are still happy with an abundance of Ponderosa and Pinon pines.
We could never scrape the little mountain that rules our front yard, or tear down our pump house, so the southwest corner of the greenhouse remains in shade. One day we may install a tilapia tank there (his idea), or wall off a guest room/office (my idea). For now, it is where we store gardening supplies, including a 55-gallon barrel for harvesting rainwater.
Most of the floor in our greenhouse is decomposed granite from our property, but we paved the front entry area with concrete, stamped to look like stepping-stones. It was inexpensive and quick, but it is a chore to keep the D.G. out of the cracks. A more pleasing alternative, emphasizing the connection between house and garden, would be to pave over the concrete with slate tiles like we used in the house entryway.
Because the ground slopes away from the house to the south, we have plenty of headroom at the eaves of the greenhouse. Terracing with native stone and salvaged clay blocks adds interest and helps buffer temperature extremes at ground level.
Heating, cooling and ventilation
All greenhouses are "solar," but not all greenhouses attempt to use the sun's energy efficiently. Those that do are effective at collecting and storing solar energy, while reducing heat loss. Any dark-colored objects with enough thermal mass (including our decomposed granite and concrete walkway) will absorb solar energy, store, and then gradually release it. We use five-gallon buckets, and 55-gallon barrels, filled with water and painted black, for heat storage. Walls and any other surfaces that are not heat collectors should be painted white to reflect light to the plants. Some people staple heavy-duty foil to the ceilings to bounce light downwards. They say this increases available light by one-third but, with the extremely bright, snow-reflected light we get, I would be concerned about too much eye-straining glare.
Every winter day, the thermometer testifies that the greenhouse temperature plummets with the setting sun. Plants don't do much until the temperature reaches 50[degrees]F, and tomatoes need nighttime temperatures of at least 55[degrees]F to set blossoms. We planted tomato seeds on January 1st. About five months later, we had green tomatoes.
Not everyone bothers with winter gardening but if you do, you need to minimize night/day temperature extremes. Having windows on the east wall helps plants to heat up quicker in the morning: Although double-glazed windows slow down heat loss, something more is usually needed.
Most people install some type of moveable insulation over the windows, but every method has its drawbacks. Interior rigid insulation is bulky and can be difficult to move and store. Exterior rigid insulation panels are often heavy, must be protected from the weather, and who wants to be out putting up and taking them down in a snowstorm? Draperies or window quilts must be substantial and fit tightly to avoid convection currents, which can result in an even greater heat loss.
We tried sewing window quilts by layering fabric, plastic sheeting and Mylar from bags that once held bulk grains. This did not go well, so we abandoned the project in favor of something much simpler. We stapled a double thickness of plastic sheeting at the top of each window. When the winter sun goes down, we unroll the plastic, tucking it in close to the window frames. Every morning we roll it back up and fasten it with clothespins. On the coldest winter nights, we supplement with a small propane heater on the lowest setting.
Ventilation is an important concern with any greenhouse. It cools, adds carbon dioxide, reduces humidity and mixes the air. It allows the transfer of humidity and heat between greenhouse and home in the winter. If high and low vents are placed between house and greenhouse, the heated greenhouse air will naturally flow through high vents into the house, while cooler air from the house enters low vents to the greenhouse for heating. For the best circulation, high and low vents should be located apart from each other. We use windows and doors for vents. We always leave a window open between the house and greenhouse--cracked in the winter, wide-open in the summer.
In the summer, high and low venting to the outdoors is necessary. The best vent placement is at each end wall. We have screen doors at opposite, ends of our greenhouse and some opening windows with screens. Overheating has never been a problem for us, although our summer temperatures sometimes exceed 100[degrees]F. Besides venting, there are several other ways to minimize the upper heat extremes, such as covering exterior windows with lathe or netting, or growing a living screen of sunflowers or trellised morning glories across the front of the greenhouse. We staple shade cloth over the clear ceiling panels to help reduce summer temperatures.
Reaping the benefits
Greenhouse plants generally need less watering and, because of the nearness to household plumbing, watering is easier in an attached greenhouse. We use snowmelt and rainwater for most of our watering, catching and dispensing it from 55-gallon drums outfitted with spigots. To further conserve water, we grow our plants in homemade "self-watering" pots. Any water not used by the plants drains out through tubing into a container to be re-used. When we need to be away for a few days, we have some success with a drip irrigation system that uses a 55-gallon drum and small pump on a timer. Any plants not connected to this system, we shut up in the bathtub. They may not thrive but they certainly survive.
An attached greenhouse can have some surprising fringe benefits. Water, sunlight and carbon dioxide are necessary for photosynthesis. Composting, raising small animals and circulating household air can raise carbon dioxide levels in the greenhouse, enough to partially offset the reduction of light in the wintertime. Circulating household air can almost double the rate of photosynthesis in the greenhouse. In return, greenhouse plants purify and oxygenate air for the house.
By building an attached greenhouse, there is one less wall to build. Heat from the house supplements the greenhouse and the greenhouse buffers the house from the winter cold.
With proper venting, humidity shouldn't be a problem. On rainy days I often hang clothes to dry in the greenhouse.
Our teenage daughter has made the greenhouse her homeschool science project. She spends hours every day watering plants, studying organic gardening techniques and keeping careful records of planting dates, yields, plant varieties, etc. I'm welcome to cut leaves from the chard or parsley, but must report to her any whole plants I harvest, such as Pak choi.
Gardening chores are more convenient--and more likely to get done, especially when the weather is bad. Coming and going, we always pass through the greenhouse, so we are more likely to notice any problems that need our attention.
Because our kitchen looks into the greenhouse, it is easy to remember to add fresh greens and vegetables to our meals.
Any garden should make you want to linger. Forget fancy, ours is functional and a work in progress--but warm, serene and a sweet smelling place to relax. It's a favorite spot to greet the day. When it rains, this is where we gravitate to listen to raindrops drumming on the metal roof and to watch nature's fireworks.
We allowed enough space in our greenhouse for bench seating, with boot storage underneath, and coat hooks on the wall. I wanted more space for a small table and chairs, but was over-ruled. "It's a greenhouse. Think plants," he said. At least, with our new counter-height dining table, we can enjoy the plants from inside the house.
The irony of lost sunlight
Although we believe the positives far outweigh the negatives, there are some drawbacks. For maximum natural lighting, they say a house should be long and narrow, so with every day working on our greenhouse we lost a little more of the sunshine that once streamed in the front windows of the house. Darkness comes earlier to our kitchen and dining room and we must now rely more on artificial lighting at dinnertime.
For the most part, animals that find their way into the greenhouse are there for the warmth and the food, and aren't interested in our home or us. When they do wander inside it is usually unintentional. We have discovered small lizards behind the couch, in the sink and in a ceiling light fixture. Rodents sometimes blaze a trail from the greenhouse to our attic. On the other hand, the sound of crickets chirping in the greenhouse is a pleasure. It is up to us to seal openings or usher the intruders back outside.
Early on, we made the mistake of bringing aphid-infested pepper plants into the greenhouse. It was a challenge to rid ourselves of them, or at least limit their numbers. In general, insects in the greenhouse stay in the greenhouse, but if they do come inside, we just haul them back out again. I heard of a woman who released hundreds (or was it thousands?) of ladybugs into her attached greenhouse and they never strayed from their food source.
When we brought home two kittens, I thought the greenhouse would be the ideal place to keep them, but my daughter set me straight. Several of our plants can be toxic to pets. I didn't want to give up the plants and she didn't want to take any chances with her kittens. We keep the greenhouse door closed now, or keep a close eye on the kittens. On the other hand, larger pets could trample plants. A baby gate or Dutch door may be needed to keep the greenhouse off-limits to them.
For us, building an attached greenhouse was a very good decision--aesthetically, with regard to energy efficiency, educationally, and we--not the deer, not the squirrels and rabbits--get to eat the vegetables we grow.
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|Title Annotation:||Homestead building|
|Publication:||Countryside & Small Stock Journal|
|Date:||Nov 1, 2007|
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