Building the Farm - High Tunnel for Season Extension
Farmers are increasingly searching for solutions to variations in climate these days in addition to always discovering ways to extend growing seasons for maximum production on limited space. One super popular choice is the high tunnel, and it has already paid off for us on our farm.
A high tunnel is similar to a greenhouse, although typically crops are seeded in-ground rather than in containers or on tables as might be seen in a nursery or greenhouse structure. The high tunnel allows for some temperature regulation, protection from frost, and also provides for infrastructure on which can be placed things to moderate temperature and precipitation - fans, shade cloth, irrigation, trellises, and so on.
Thankfully for Quelite, we have a great group of Bastrop County USDA agents who helped us apply and eventually qualify for a grant under the Natural Resource Conservation Service. This grant covered about half the cost of the high tunnel we built, and I cannot recommend seeking them out for this assistance and other questions and support. We’re required to grow in-ground with the goal of soil improvement for 5 years, after which we have the freedom to use the tunnel as we see fit.
The tunnel itself came as a kit from Growers Solution, an outfit out of Tennessee that has some really great products and absolutely stellar customer service. It showed up on a truck as a few dozen pieces of shaped steel, a box full of hardware and fasteners, and the massive rolls of poly sheeting which would cover the whole tunnel. I was equally excited and overwhelmed at delivery time, and I only half-jokingly asked the driver to stick around and help me get things going.
We opted for a tunnel that measures 20 ft x 88 ft with 8 foot roll-up doors on either end and high, 6 foot sidewalls that can be rolled up and down depending on conditions.
As a one-man show, construction was somewhat slow, and required lots and lots of verification of measurements. A few inches off square and the whole thing could get goofy quick. Our clay soil was as unforgiving as ever, and I opted for a gas-powered post driver to get the 44 base posts over 2 feet deep. From then, it was a series of trip up and down the 10 foot ladder, sweating like death, lugging drills and screws and all manner of clips and ties.
Perhaps the hardest and most frustrating day was, ironically, the one day I had help. My family happened to be around, and I took advantage of their willingness to get the plastic sheeting up and secured (probably 110’ x 45’ and weighing maybe 200 lbs). There’s no better way to test the presence of wind than standing on a ladder trying to keep what amounts to a gigantic sail from flying in one direction or another - and taking you with it! We got it done, though, and she stands as the largest and most impactful structure on the farm to this day.
During our first winter with harvestable crops, we had an early freeze that lasted about 3 days with temperatures never eclipsing 32 F, which meant sure death for most of the crops in the field (not to mention power outages for many, many people in Central Texas). The expected high winds convinced me to not try too hard with my frost cloth and hoops in the outside, main garden plot. I decided to test the inside of the high tunnel, where I was successfully growing and harvesting kale, chard, carrots, beets, and lettuce. I thought it better to try to save what I could in the high tunnel by devoting myself fully to warming those crops, even though I knew that meant sacrificing the lion’s share of the things we’d been growing.
In the end, the gamble paid off, as the wind and the cold would have obliterated the frost fabric outdoors. Inside the high tunnel, all buttoned-up and covered, I registered temperatures in the 40s when outdoor air temperature was more like 26. Because our crops aren’t used to teens and 20s, that would have certainly done them in. Instead, we weathered the 4 days, and continued to eat on those crops throughout the remainder of the winter. In fact, we only decided to pull or mow those crops until the following spring, when time came to prepare the soil for tomatoes and cucumbers.
While we may have been limited to food for our family rather than for market, we saw the immediate value of the high tunnel in volatile weather. It’s fair to say that another high tunnel may be in our near future.
Currently, the high tunnel has rows of cucumbers and tomatoes, and we’ve installed shade cloth along the length of the structure. In a summer as hot as we’ve had, it’s kept those crops going, even without much rain and without irrigated all that much. Fans, mounted to the interior trusses of the tunnel, keep the temperature reasonably low, considering we’ve been living at 100+ for a few months now.
As we move forward, I foresee the addition of another tunnel or two. It allows for longer seasons, protection from destructive elements, and quicker reaction time to changes in weather and other conditions. While we do lose natural rainfall on the crops in the tunnel, we are better able to moderate the quantity and timing of water we do apply. I plan on installing a water catchment system on the tunnel we do have, which could be used for crops inside or fruit trees in other parts of the property.
