How to build an affordable greenhouse.

For those people who want smaller or less expensive greenhouse, the Grow-Box Gardens book has a couple of plans that don't cost much, yet are sturdy and practical. Chapters 10 and 11 are devoted to building two different small greenhouses. Go to the Store at www.growfood.com, click on Grow-Box Gardens, and you can download chapter 10 free. This small house has a strong wooden frame that is supplemented with PVC pipe.

Many people tout their own favorite greenhouse plans as the cheapest and best. We're sometimes asked what makes the Mittleider designs better than the hoop-house tunnel ones, or the glass paneled ones, etc. Folks also ask if the "permanent" one in the Mittleider Gardening Course would be difficult and expensive to move.

The Food For Everyone Foundation is very concerned with helping people do things the most economical way. However, that is not always the most cost effective way at the outset.

The continuous ventilator greenhouse plans don't have to be permanent! My greenhouse at Utah's Hogle Zoo Garden is on stirrups and is entirely screwed together for quick dismantling and removal; it's covered with a single sheet of 6 mil greenhouse plastic; it has the best natural ventilation system of any comparable-sized greenhouse in the world, and it costs virtually nothing extra.

Anyone with a garden large enough to need a greenhouse this size will be greatly blessed financially by doing it right. There are many reasons why this greenhouse is better than the cheap hoop-type or tunnel, given the sizes are comparable, including:
1) It's structurally very strong, and will not be blown down by storms.
2) Strong built-in tables keep plants off the ground avoiding cold, wet, bugs, and diseases.
3) Built-in continuous ventilators in roof and sides keep plants cool in hot weather without electrical fans.

These greenhouses have been built, tested, and proven cost effective in many countries throughout the world - from 60 degrees North latitude in Russia to 20 degrees South latitude in Madagascar - and many are still in use after 25 and 30 years. Remember that initial cost is only a small part of the investment equation.
In deciding whether a greenhouse is really worthwhile for you, and in deciding what kind you should build, whether quanset/tunnel, PVC, steel rebar, or wood, please consider some greenhouse issues Dr. Mittleider has dealt with - and the way he recommends they be handled. While every family's situation may be unique, there are several common elements, and we will discuss how to avoid three common problems.

1. Build your greenhouse strong enough to last, rather than have the first heavy snow load break it down, and so we recommend a wood or steel frame - at least for your main structure.

2. The second issue is heating/cooling and air flow, which is almost as important as the first. Unless your quanset or tunnel-type greenhouse can have the sides easily rolled up, you will likely have problems with cooling in the summer months, because electric fans are expensive, and not always even available in gardens.
The continuous ventilator running the length of the roofline on the Gardening Course plan is the best solution in our experience, since heat rises, and venting out the top eliminates the hottest air while drawing in cooler outside air from the sides and ends. On large structures and in hot climates we also have at least one side able to roll up from table height to the roof line, thus increasing the venting to the maximum. We recommend screen be placed on all venting areas.

3. Make your greenhouse tall. When growing seedlings you'll want all your plants off the ground on tables. Some tunnel/quanset plans are very low, and plants are on or in the ground. Using tables will help avoid problems with pests and diseases, which will spread like wild-fire in a greenhouse if they get started.

To summarize, the "continuous ventilator" wood structure design is our first choice, and as a second choice we recommend the plan in chapter 10 of Grow-Box Gardens - making sure you allow for rolling up the sides for continuous ventilation.
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