Protecting high value food crops from the weather is an ancient science, art, and practice. As far back as the beginning of the first century, the Romans were tinkering with environmental modification. And so it has been down through centuries that just about every imaginable technique and device has been used to shelter crops from the ravages of harsh climates.

What a sight it must have been around Paris in the 1700s to see thousands of glass bell jars covering acres of vegetables. Each plant has its “private” greenhouse! English farms were covered with glass cloches. In this country only a few years ago, many vegetable farms in this country were dotted with rows and rows of hot tents.

For more affluent growers, glass-glazed greenhouses became the zenith of protected growing. With the advent of WW II came polyethylene, a multi-use product that quickly found its way into agriculture for mulches and greenhouse coverings.

Then came plastic row covers for low tunnels, and agrotextiles as floating covers. At the other end of the spectrum, highly sophisticated greenhouses, and even growth chambers, rose to the challenge of more perfect environmental control, albeit at a rather high cost of investment.

And then it happened — just like a quarterback sneak on a football Saturday afternoon, a surprise play was made in protected agriculture. High tunnels suddenly came on the scene as a new twist in crop production. Sandwiched between low-tech row covers and high-tech greenhouses, high tunnels made their debut in New England in the mid to late 80s. There was no fanfare, just one big exciting challenge.

Much of the success of high tunnel use in the United States can be attributed to a very resourceful farmer/grower, Ed Person, in Moultonboro, New Hampshire. Living in a region with only about 120 frost-free days, he needed a structure (but not a heated greenhouse) to protect his crops from the incessant low night temperatures of spring. After experimenting with some rather cumbersome plastic-covered “pens,” he looked for a commercially manufactured structure. Not finding what he wanted, he designed and built a high tunnel with roll-up sides for ventilation. Today Ed is both a farmer and a manufacturer of very thoughtfully designed and sturdy high tunnels (and greenhouses).

In a sense, we are in a catch-up mode when it comes to the use of the high tunnels. Growers around the world – Europe, the Mid-East, Japan, South Korea, Taiwan – have been using these relatively inexpensive structures for many years. Now our time has come, even if late.
How do we know if high tunnels really work or if we have another fad on our hands? Well, for one thing, growers do not make a living on fads. From what we have seen in just a decade +, the rapid adoption of high tunnels by growers for intensive crop production is a good indicator that they are serving a good and profitable purpose. Crops mature earlier, crops have enhanced quality, and the pay-back for the high tunnels is very short – less than one year for many crops (depending on marketing opportunities.)

From 1988 to 1998 the number of high tunnels (14’ x 96’ units) in New Hampshire increased from 15 to 175. By 1998, the gross returns per year for high tunnel tomatoes were right at $1,000,000 per year. Early maturity, high yields, and retail sales accounted for high returns.

As more and more growers use high tunnels, the number of crops and cropping sequences continue to expand. It is close to fact to say that any crop that can be grown outdoors can be grown in a high tunnel – profitably and sustainably. (Always some exceptions.) Vegetables, fruits, and flowers are all on the list.

A decade of high tunnels has blazed a new path into protected agricultural production. Low capitalization, early maturity, higher yields, enhanced quality, and flexible cropping schemes are quite descriptive of a growing system that has pushed a 120-day growing season pretty close to a 365-day growing adventure.

High tunnels have made their mark and will continue to serve a critical need in sustainable agriculture – throughout all of the country.

Otho Wells is Emeritus Professor of Plant Biology at the University of New Hampshire. His research career has focused on protected agriculture, and he is a leader in using high tunnels for vegetable production.