BOONE – Two dozen visitors to Northwest Greenhouse and Floral Inc., in Boone took a look Sunday at what Mike Salama said he’s learned about growing tomatoes hydroponically – without soil.
Salama is a second-generation greenhouse grower and is in his second year of his experiment. His No. 1 tip?
“Start by keeping it simple,” he said. “Right now, I have too many varieties going and each are growing at different rates.”
Salama is using his parents’ existing hydroponic system that was used to grow cut roses for the business.
Growing roses through the winter, Salama said, was a burden when energy rates skyrocketed since the greenhouse retains no heat at night.
Looking for another revenue stream, Salama said he hit on growing tomatoes in the hydroponic system to sell into local grocery stores and restaurants, and as an added draw to the family’s floral and bedding plants business.
Northwest Greenhouse, Salama said, uses a buffer known as coconut coir as the growing media for hydroponic production.
Plants grown hydroponically can be raised in a range of non-soil-based substrates.
“We control irrigation and the flow of air to lower fungal disease,” he said, “and we don’t have to deal with deer, rabbits or other tomato-loving animals that eat field tomatoes.”
The irrigation of the plants is through a drip line. The water carries nitrogen and micronutrients, which is automatically monitored and the solutions mixed.
Unused water that reaches the end of the rows is pumped back into the system.
Tomato production starts at the greenhouse in early December, when the previous year’s plants come to an end and new plants are seeded.
He starts the plants by seed in soil.
“We transplant these plants into their hydroponic home around the end of February,” he said, “and once they fruit, we’ll have fruiting tomatoes until around Dec. 1.”
In fact, two varieties of his grape tomatoes – red and yellow – and a heritage black cherry tomato were ripening.
Tubs of the fruit were available for Sunday’s visitors to enjoy.
Salama said he doesn’t push the tomatoes to produce through the coldest parts of winter because the cost of raising the plants would be too high to pass on to consumers.
“It’s too cold, and there’s not enough light or energy to make it worthwhile,” he said. “So we just stop tomato production and sanitize everything to prepare for the new crop.”
Salama said the two biggest challenges he was facing on Sunday was keeping up with suckering – the process of pinching off unproductive shoots, called suckers -and keeping the pH and electric conductivity levels in balance for plants’ needs as they grow.
The concentration of the nutrient solution is measured by its electrical conductivity, which is its ability to conduct electricity. That property of the solution is a function of the elements in the solution which conducts the electricity. An EC meter detects the level of total dissolved solutes in the solution.
“The trick is getting the right EC on cloudy and sunny days with the different varieties,” he said. “The water amount is dependent on sun accumulation, based on a number of footcandles of light they absorb, plus adjusted as the plants get bigger.”
Salama said there is just himself and one employee, an Iowa State University horticulturalist, keep the thousands of tomato plants trained, suckered and harvested.
He said the plants will continue to grow to 30 to 40 feet tall and to keep producing fruit until it gets too cold.
Salama said he’s not happy with the drip line system, since if a plant dies, “I’m wasting nutrients.”
He said he will try an emitter system in the future, providing one per plant. If a plant dies, the emitter is turned off.
Pruning is essential, Salama said. As fruit is harvested, leaves are pruned to one layer under the next level of fruit. That keeps all the plant’s energy in growing new material and setting fruit.
Pollinating tomato blooms is accomplished by either shaking the plant or using a device that vibrates the plant. Bumblebees would be better for pollinating, but they are too aggressive to be inside a greenhouse.
Salama said a good ventilation system is needed to keep plant diseases under control.
“So far,” he said, “we haven’t had any root diseases.”
When asked about white fly infestations, he said these are primarily kept under control by regular pruning and suckering, and getting all of the egg-ladened organic waste out of the greenhouse.
“We keep it real clean in here,” he said.
Farmers Heather and Kent Friedrichsen, of Perry, attended to get insights into growing vegetables in greenhouses.
“I’ve farmed all my life,” said Kent Friedrichsen, “but farming is changing.”
The Friedrichsens, who have an organic berry farm, said they have studied growing fruit and vegetables for local markets in greenhouses and in high tunnels.
“We always like getting into a greenhouse to see how they do it,” Heather Friedrichsen said.
“I always want to know is what else can you do with it,” Kent Friedrichsen said.
A longtime experienced greenhouse grower, Mike Carter, of Hidden Acres Ranch, in Coon Rapids, said he attended “because I’m interested in any diversification in ag.
“Anything we can raise to eat gives us food security.”
Noting that local food producers are less likely to grow or sell anything they won’t eat themselves gives consumers confidence in local foods and keeps them from becoming dependent on food from other locales.
“A hungry population,” Carter said, “is a restless population.”
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