Greenhouse Structures: It’s All In The Planning
September 5, 2016 
Making the right decisions about your greenhouse structure well in advance of construction is critical to the success of your business.
First of all — and an important caution for new growers — start small. If you have never grown hydroponic vegetables before, there is a very steep learning curve. Greenhouse-grown is not the same as field-grown, and is not even that similar to high-tunnel grown. There are new technologies to master once you take the crop indoors.
In deciding about the size of the plot of land for your greenhouse, be sure you take into account whether you will be a wholesale or a retail business, or some combination of the two like many growers. If doing retail, you need to have adequate parking for customers and employees, in addition to a customer-friendly driveway or access road. If wholesale, you will need room for trucks to comfortably get in and turn around. A 2-acre lot would be the minimum size to think about for a small business.
Location And Signage
Location of the greenhouse business should include thinking about proximity to main roads and highways. Delivery trucks for wholesale need ready access to highways. Retail customers will find you much better if you are on a main road, which is relatively busy, especially if it’s not far from a residential neighborhood. And don’t forget to have excellent signage to help them get to your place.
Either way, it’s good to have extra space in the lot in case you want to expand someday. Once you learn how to grow the crop successfully, then it’s time to consider expansion. The easiest way is to add on new bays connected at the gutter — gutter-connected bays.
Another area of concern is to be sure you are not downwind from pollutants that might make your production impossible. In rural areas, this includes agronomic crops that require aerial sprays of herbicides, such as cotton. In locations near cities, beware of coal-fired power plants.
The greenhouse structure, with its exhaust fans at one end and pulling in air from the intake end, is similar to a vacuum cleaner sucking in outside air. If the pollutants are outside, the fans will readily bring them in.
Don’t forget — your greenhouse plants need full sun. The greenhouse should not get any shade from tall buildings or tall trees nearby. Think about cutting down trees that will not only shade the greenhouse, but also could fall onto the greenhouse causing significant damage.
Light level also can be decreased by locating in an area with particulate pollutants — factories, power plants, smog, etc.
Consider Climate
What about the climate? Is the area prone to high winds (tornadoes, hurricanes, and straight-line winds), lots of hail, long periods of freezing temperatures, very heavy snow loads? None of these rule out growing a crop, but structural modifications and environmental controls need to be installed to accommodate temperature extremes and severe weather.
Where will all of the water go? Plants only use a portion of the water applied. The rest has to go somewhere. The greenhouse should be 6 to 12 inches above grade so excess water will drain off.
The floor should have a 1% to 2% slope (1 or 2 feet for a greenhouse about 100 feet long). Puddles in the greenhouse will be a source for disease inoculum thriving, which could spread to your crop.
Also, algae growth on wet floors can cause slippery spots leading to falls. Many growers use gravel as a base whether it is covered with a woven, permeable ground cloth or not.
Concrete is nice but not required. If the greenhouses are free-standing (e.g., not connected at the gutters), cut swales between them to keep the water flowing away from the structures.
There are so many other things to think about before picking the best location and deciding upon your greenhouse structure.
Don’t forget about access to plenty of good, clean water, electricity, and heating fuel. Get your water tested by a reliable testing lab before you make the plunge.
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