Extending the vegetable growing season with low cost quick hoops
We’ve continued to experiment with row covers on the farm this year. We covered about 1800 linear bed feet, or 5,400 square feet of actual growing bed, on the 26th of October of 2012, using EMT hoops bent on farm, making nine low tunnels 100 feet long, 6 feet wide. The hoops were set approximately 10 feet apart, with 10-foot-wide row cover draped over them, staked taut at the ends, and weighed down at each hoop with a sandbag (filled with compost). Each tunnel covered two 30 inch beds and a 12 inch path. Tunnels were separated by a 24 inch path. Crops covered included carrots, baby lettuce, beets, chard, kale (several varieties), head lettuce, radishes, scallions, and spinach. We had representative areas of the same crops which were left uncovered for comparison. Most crops were already being harvested by the time we covered them. This spring, which was exceptionally cool and wet, we planted two 150 foot low tunnels with cucumbers and summer squash, to protect them from both bugs and frost. We purchased a temperature monitoring system.
RESULTS TO DATE
So far, we’ve had a lot of success over wintering and extending the season on most of the crops we’ve tried. Notable exceptions are radishes, which seemed to bolt much faster under the tunnels, and lettuce (baby leaf and head), which was frostbitten by relatively mild temperatures. Crops left uncovered are almost always decimated by the first of December, with the exception of kale and spinach, but the beets, carrots, spinach, arugula, and kale under the covers was thriving until the covers began to rip in late December, into January. Keeping the covers tight and anchored well are key to avoiding rips, but once one starts, it’s impossible to stop, leaving a big gap in the tunnel. We are usually able to secure the ends of the tear, but it usually means the loss of 10-20 feet of covered bed. Tears are usually caused by abrasion from excessive winds (we are on a windy hilltop), or by accidental tears while covering and uncovering the crop to harvest it. One of the most notable observations from this winter was a double bed of beets which we had covered, but which developed a rip within a month of covering. The covered beets had beautiful, very attractive tops, making them easy to bunch and sell in December, when there were no other fresh beets at market, but the uncovered beets were frozen down to the ground. The roots of both were harvestable, but the tops make a big difference in marketability. Carrots were similar, although in that case, uncovered carrots were even damaged on the top of the roots, leading to spongy and cracked shoulders, while the covered carrots did not suffer the same effects. Over all, the low tunnels are very effective for spinach, which overwintered, and was harvestable until February, and again after the middle of March; kale, which did not overwinter (bolted) but was harvestable for December and January; beets, which were harvested until they were all gone in January; and carrots, which lasted all winter. Of course, harvesting from a low tunnel is not as convenient or comfortable as harvesting from a greenhouse or high tunnel, as much of the time in the winter it’s muddy and cold in the field, while it’s usually much warmer and drier in the greenhouse or tunnels, but the cost is so much lower that it still pays quite well, even if it means not being able to harvest every time we might like to, because sometimes the row covers don’t thaw out all day long, or the mud is too deep to allow for a good harvest. Below is the rough estimate of costs as we figure them on our farm, not including labor; Cost per square foot of coverage: Greenhouse- $10/s.f. up front, $.38/year with lifespan of 30 years, new plastic every four years High Tunnel- $3/s.f. up front, $.22/year with lifespan of 15 years, new plastic every 4 years. Low tunnels/ quick hoops- initial cost $.09/s.f. $.027/year with lifespan of 7 years for hoops, annual row cover replacement. Our attempts at temperature monitoring have been frustrating, to say the least. We purchased an Acu-link monitoring system from Acurite systems this year, and at first it worked great, but within two weeks we began to have problems receiving the signal, getting intermittent readings, and by two months in, we were having almost total failure. The weather station which is part of the system is great, but the independent monitoring devices don’t seem to be cooperating. We’ve got some leads which we hope will solve the problem, and we’ve got some electronics ordered.
WORK PLAN FOR 2013
This year we hope to expand our low tunnel coverings, and experiment more with the heavier coverings. We want to be able to install the temperature monitoring devices right at the beginning of the fall season, and track temps through the winter.
We presented at the Small Farm Today, National Small Farm Trade Show and Conference in Columbia, MO this year, as part of the NCR-SARE Farmers Forum. I presented about extending the growing season at the Great Plains Vegetable Growers Conference this winter. We also hosted tours from the Missouri Organic Association, several Horticulture classes from Missouri State University, Ozarks Technical College, and an ecology class from Drury University. Along with that, we’ve hosted dozens of aspiring and current growers for one-on-one farm tours this year. Altogether, we’ve hosted over 300 visitors this year, and all of them have seen our low tunnels and hoops.