Greenhouses, Part 1

Greenhouses can offer close to ideal conditions for plants, growing things is almost as easy as picking up a watering can. All you need is at least three hours of sun per day and an undying passion for living things. Greenhouses are available in pre-fabricated units that can be put in place in less than a day. Others can be attached to the side of the house. You can select size and complexity to fit your interest. You can grow almost anything- from the most exotic of passion-flowers to a modest row of carrots. The palm, cactus, geranium, primrose, fern, begonia, and African violet all thrive in a greenhouse. But you will have to learn to do things a little differently than you do with outdoor growing. First, how big a greenhouse do you want? What are you going to grow in it? Are you going to use it during cold months and need a furnace to heat it? Half the glory of a greenhouse is its profusion of color and foliage, regardless of the weather outdoors. Sun - and lots of it- is the key to greenhouse success. Unfortunately the tilt of the earth in winter means the sun barely slides along the treetops before disappearing below the horizon. Days are shorter, and the increased distance and widened angle weaken the sun's warming rays. Therefore, the greenhouse has to be cleverly placed to capture the most sun possible. Because the sun spends most of its winter days in the southern sky, the ideal direction for a greenhouse to face is south. Keep in mind that trees, buildings, and other obstructions can rob plants of valuable sun. Deciduous trees, which lose their leaves in the winter, can provide filtered shade in the summer. Wind can be a factor, too. A greenhouse that is constantly buffeted by frigid winds is difficult to heat and often drafty.

For most home greenhouse growers, a 12' x 12' greenhouse gives them plenty of room to start seedlings, propagate plants or grow some vegetables. A green house is basically a transparent bubble engineered to admit the sun but keep out the cold. This means it can be made with a wide variety of materials-from aluminum and glass to a wood frame covered with a thin plastic film. Aluminum and glass structures are most popular because of their strength and durability. Plastic structures are not so attractive and must be recovered every year or two. But their lower price makes them a tempting alternative.

A greenhouse can go from 40ºF in the early morning to 120ºF by 10 a.m. You may want to invest in some louvers equipped with an electric motor and a commercial fan that comes on after the greenhouse reaches a certain temperature. You can set the fan for 80º because most  plants like it between 70ºto 75º.When it reaches 80ºin the house with the thermostat placed at bench level, the fan comes on, draws in cool, dry air and it exhausts the hot air through the louvers. But too much heat is not the only reason for proper ventilation. Good air circulation, even during the winter months, increases the supply of carbon dioxide to plant leaves and stems, prevents the spread of disease, and contributes to the even distribution of heat. You will also want to build some benches. The benches keep the plants warmer(heat always rises) and it is easier on your back to have your work at kitchen counter height. My benches are made from PVC pipe with translucent plastic sheets on top. With a smaller shelf on top, a good size shelf in the middle and room underneath I can accomodate a lot of plants. The plastic is easy to clean and doesn't harbor molds and bacteria.

This is the first of three parts, in the next two weekly newsletters I will talk about planting medium, growing greenhouse plants, watering, feeding greenhouse plants, pest and disease control and greenhouse sanitation.


There are other steps you can take to keep problems away.Remember that landscaping choices can contribute to a healthy garden: if you include a variety of plants of different heights, you'll provide a habitat for insect-eating birds and other creatures that help keep pest populations under control. Pay attention to maintenance: keep an eye on the accumulation of debris such as old leaves, pieces of wood, pulled annual flowers, and fallen seedpods. Although such materials--if nondiseased--can act as a good natural mulch (and a source of nutrients as they decay and work into the soil), they also provide a favorite home for ground-dwelling pests. If pests of this sort are a nuisance for you, you may want to clear away their hiding places periodically.



3 parts cottonseed meal, soy meal, or blood meal

2 parts finely ground raw phosphate rock or steamed bone meal

3 parts wood ashes

1 part dolomite limestone 

Mix all materials. Apply 1 pound of fertilizer for each foot of the drip line diameter of the tree.


Composting is a method of speeding natural decomposition under controlled conditions. Raw organic materials are converted to compost by a succession of organisms. During the first stages of composting, bacteria increase rapidly. Later actinomycetes (filamentous bacteria), fungi and protozoans go to work. After much of the carbon in the compost has been utilized and the temperature has fallen, centipedes, millipedes, sowbugs, earthworms and other organisms continue the decomposition.



"If you have a garden and a library, you have everything you need."


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