by Bill and Mary Weaver
The stems of the tomato plants in Andrew Serio’s two greenhouses in Preston MN, where he grows organic tomatoes year-round, are currently about 20 feet long. Attached to strings with clips, Serio drops the stems every time they reach the tops of the 10-foot-high strings where they gradually curl more and more around themselves. “By the time we’re ready to pull them out and replant, they’ll be about 30 feet long,” he explained.
Unlike many greenhouse tomato growers, Serio has found it pays to grow tomatoes in his greenhouses year-round because he has organic grocery store customers willing to pay for his organic tomatoes even through the summer, when local tomatoes grown outdoors are available. “During the winter, though, I have the locally grown organic tomato market to myself,” he added, a real plus at the local farmers market.
Andrew and his wife Jennie are hard workers, willing to put their desires on hold as they put all their energy and extra finances into building their dream: the greenhouse tomato business. They have been able to get started at a much lower cost because of Andrew’s skills in electrical work, plumbing and electronics. He hired no outside help for the construction of the greenhouses, which are now completely automated, with computerized controls for irrigation, injection of fertilizer, lighting, heat and ventilation.
Growing up on a dairy farm, he discovered he had a talent for making almost anything work, and those experiences have served him well in building his business. In addition, “Andrew has a very green thumb,” said Jenny. His skill as a grower was evident in both the lush, healthy tomato plants as well as the leaf lettuce plants, tucked 500 to each side of the smaller greenhouse, in a slightly sloping PVC pipe planting set-up of his own design.
Serio’s packing room/workroom/control room, which is directly connected to the two greenhouses, is insulated with 2 ½ inches of sprayed-on polyurethane on the walls and ceiling, as is his small cooler.
The solid urethane layer gives a high R-value with no cracks, saving on the cost of the natural gas. In addition, “When humidity gets high in the greenhouses, even with the fans on and the vents open, with any other type of insulation, the moisture would seep into the wood and rot the walls,” he explained. “With sprayed-on urethane, that will not happen.”
The first year, Andrew worked six days a week driving a fuel truck. Jenny also had a full-time job with an hour commute each way. Being short on sleep is a way of life they have accepted for the time being, and probably well into the future.
Fortunately, when Andrew and Jenny take their organic leaf lettuce and greenhouse tomatoes to the local farmers market on Saturdays, they have the help of Andrew’s retired dad, August. “On market days, we get up at 3:30 a.m. to load the van with produce picked and packed the day before.” With a considerable drive to the market, the Serios leave early so they can drop off ordered tomatoes and lettuce at an organic grocery store, before heading to the farmers market to set up before the early customers arrive.
After market ends, Andrew delivers orders to area restaurants. Marketing his whole crop has never been a problem.
Sundays are spent catching up on work in the greenhouse. Andrew and Jenny transfer two-week-old lettuce plants, grown under lights in the work room, to individual pellets so they can be put into harvested spaces in the PVC pipe planting system in the greenhouse.
“The first year, we grew the lettuce in a vertical tower system,” continued Serio. “We were not satisfied. The water ran out onto the floor, and the roots got so long and matted inside the tower that they actually rotted.”
For their second crop year, Andrew invented his own planting system, still in use, of slightly sloping horizontal PVC pipes. To solve the problem of raising the water level high enough to reach the pellets, he inserted a length of PVC pipe into extra holes drilled into the horizontal planting pipe to back the water up, making it deep enough to keep the pellets and the emerging small roots moist.
The Serios chose a clam shell pack for their organic grocery stores, with a large, brightly colored label. The six-week-old lettuce, after the roots have been trimmed short and the heads have been spray-washed, must literally be forced down so the clamshell lid will close.
Likewise, when the lettuce for restaurants and farmers markets is packed the lids must be forced shut. “The lettuce leaves are so full of moisture and so fresh, that when lids are opened, the leaves spring back with no sign of damage, looking as fresh as when they were picked,” Andrew explained.
Before the lids go on, Andrew gives the leaves a spray of water, wetting both the leaves and the stubs of roots remaining. He has never had problems with leaves drying out or bruising, even with occasional lettuce plants picked at seven weeks, making it extremely difficult to close the lids.
In addition to farmers market and direct delivered sales, some restaurants and other customers come to the farm to pick up product. To hold lettuce and tomatoes for a short time, the Serios’ use a framed-in cooler that could not be simpler. “The best temperature for holding tomatoes and for putting harvested lettuce into a dormant state is 58 degrees,” explained Andrew. “With the excellent insulation of the sprayed-on urethane, that temperature can be held precisely, year-round, with the use of a small air conditioner set at its lowest setting.”
Fertilized irrigation water from the tomatoes in both greenhouses is reused, “but only on the lettuce. If I would reuse it on the tomatoes, if I had one plant with disease, all the plants would quickly become diseased.”
Minnesota, with its mid-continental climate, gets quite hot for extended periods in summer. The Serios manage to get through the summer without the greenhouse overheating enough to make the tomato pollen abort by using a so-called “swamp cooler” used in dairies and hog houses in the south to cool without the cost of air conditioning. He installed one of these evaporative coolers in the south wall of each greenhouse. “It’s a sealed system. Insects can’t get in through a waterfall.”
Serio Farms Greenhouses
by Bill and Mary Weaver