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The public seldom gets the chance to see where plants they select in a garden center are grown. In this commercial greenhouse tour you may hear a bit of what it’s like in this plant business, find growing tips from a professional, and experience this grower’s standards.
Korey Mensch and his father Lyle are co-owners of Mensch Greenhouse, Inc., in Avon, SD. They ship their plant crops to independent garden center and grocery store clients throughout South Dakota and Nebraska, and a bit into Iowa and Minnesota. “Color Your World” pots with rainbows are their trademark.
Mensch Greenhouse grows and supplies annual bedding plants, baskets, planters, window boxes, perennials, woody plants, and ornamental grasses. Their niche market clients ask for many kinds of plants, but growing the wide range of plants presents challenges. They have many crops with different growing requirements. In fact, the business has several specialty greenhouses with two and a half acres under roof.
The commercial operation employs thirty-six workers at peak season, mostly from the Avon area. About a third are high school students who work on Saturdays and after school. Korey, thirty-eight, has worked in the greenhouse business all his life, and has loyal employees that pre-date him.
We step into a half-acre year-round greenhouse world, leaving icy winds of early spring behind. Plants fill the benches and baskets of green fill the roof space. Locals in Avon, a small town with population around 625, know of this business that has evolved since the 1960’s, but not all have seen it up close. Even avid gardeners who toured the greenhouse from Tyndall, the next town east, were surprised at the scope of this business nearby, according to Mensch.
“Summertime every day,” Mensch said. “In a year like this, it costs a lot to keep it summertime.” He refers to the sharp rise in propane gas for heating the greenhouses. “We hope to be able to absorb the costs. If [garden center] customers have a price increase, then the end consumer has to pay more.” The greenhouse supplies plants and hopes the demand is there.
One of the big challenges to this grower is timing. “May 2nd is always the same day on the calendar every year and we gear for it. But in 2012, people wanted plants in April because the weather was nice. Plants have a shelf life. To get everything timed out, [now] is my biggest window.” For June he times plants in steps for shipment later in the season. “Because it’s a long season, I rather have my crops on the small side than anything overgrown.”
Supplying spring bedding flowers and vegetable plants to a large geographic region is a challenge. “Rapid City is maybe a week earlier than Sioux Falls, but on a given year, we could be selling plants in Sioux Falls and getting snow in Rapid City. When we delivered plants up to the North Dakota border last year, water still had three feet of ice.”
What Grows Here Doesn’t Stay Here
Calibrachoa [mini trailing petunias or million bells] are our Number One ten-inch basket,” Mensch said. Several colors and calibrachoas in four-inch pots are also available.
“The first two years we grew calibrachoa, I had bad information. Iron and fertilizer needs were intensive. We took a couple of years off and looked around for better genetic varieties. All the companies have better genetics now. Calibrachoa are easy to grow now because they fit with what we do right for everything else. Some [growers] still have trouble growing them. We have a good source, an excellent transplanting crew that take care to plant them not too deep and not too shallow.”
In the specialty greenhouse before us are rows and columns of four inch pots of calibrachoa, all bright green and the same compact size, all with their tags aligned to the right like a regiment of tiny soldiers as they grow ready for planting.
“[Annual flower and vegetable] bedding plants are our Number One product. My flats are more uniform than anyone else’s,” Mensch said. “That’s what I’m about. I want the last flat as good as the first flat.” Gardeners often appreciate plants of the same size or maturity in landscape projects or gardens.
Lantana is a hardy sun-loving plant that has increased in popularity over the years. “We grow lots more of it now. It keeps mosquitos away. It comes in pink, orange, red, rose and purple,” Mensch said. His tropical greenhouse has rows and rows of lime green and dark sweet potato vines, dragon wing begonias, and banana trees in pots.
Pansies, snapdragons, dianthus, and dusty miller grow in cooler conditions in another greenhouse. Large containers in greenhouse storage there will soon be filled with blooming flowers for Avon Main Street. Mensch will see that the pots are tended all summer.
Mensch is attuned to social media and gets special requests about plants mentioned for plant projects. “Pinterest may be spurring interest in plants. I get calls for certain plants. Last mid-season, Proven Winners’ ‘Blue My Mind’, which has a striking blue flower had a lot of calls. We now have extras of this flower.”
His Facebook friends ask him: What is kale and what do I do with it? “I’ve been eating it my whole life,” he said, and mentioned ornamental and edible kale variety bedding plants they grow.
Some popular or hot items may be harder to grow. “Gerbera daisies are so much eye candy that people can’t resist them. But they are for the right spot in the right yard,” he said. “For the true gardener that loves to tend plants, their palate’s wide open when they walk into a greenhouse. They want to care for plants and know where to plant it.”
Casual gardeners find matches of time and effort to their interest with other plants. “Petunias, moss roses, and [annual] vinca are bullet proof and will look good almost no matter how you treat them,” he said.
Blending Hand Work and Automation
“We [Korey and his father] micro-manage everything,” Mensch said. “I have to know what everyone’s doing at all times. We stay in control of when water goes on and off. No timers. Everything here is weather dependent. If we’ve had three sunny days in a row, it ‘s time to check the baskets.”
Various sizes of hanging baskets are grouped to fill the roof area of the greenhouse. They’re hung at two levels for maximum light and use of space. Baskets rotate on a chain system like a horizontal chair lift to receive an automatic shot of water and fertilizer.
“When we plant, we don’t keep the soil wet. We let the soil dry out between waterings. This basket is dry. It shows me by the color of the leaf that it is dry [a touch of gray] and time for water. You produce more roots when you stress the young plant and less disease takes hold,” he said.
“We collect rain water from our greenhouse roof gutters (21,000 sq. ft.) and run it into a cistern. Since we haven’t had measurable rain this winter, we splash rural water into the cistern.” Gardeners sometimes rest an open bucket of water overnight to release the chlorine gas before watering plants.
A shade cloth over the greenhouse roof blankets the building at night in early spring and keeps the air during the day in summer. Roof vents help circulate air.
All the flats, pots, and window boxes are filled consistently with soilless mixture using what they call a “dirt machine”. “Peat, perlite, bark, and vermiculite are in the soilless mixture for water-holding capacity,” Mensch said.
“Seventy- five cu. ft. bags of the mixture are hoisted up and contents are dropped into a hopper. Chain system under the hopper moves containers along to receive fluffed soilless mixture and the tops of all filled containers are leveled off.”
Many plants are hand transplanted but automation is used on some plants. “We work with so many petunias that we use a transplant machine that plants forty eight plants at a tine. Workers check to make sure all the plants are planted just right, put the tags in, and take them to the greenhouse to grow. Impatiens plants bend over and break with this machine. That’s not acceptable at Mensch Greenhouse.”
“With the exception of a large greenhouse, there’s no need to over-automate everything,” he said. “We’ve got great help. It costs money but the money is great for a small town. My friends in the industry, when their machine goes down, they’re flat out of production.”
From When This Started Until Now
His grandmother, Ada Mensch began arranging flowers for special occasions in her Avon flower club as a hobby. “My grandfather Phillip ran the elevator in Avon. He was advised to cut the stress out of his life and get out of the business. He and Ada went to a greenhouse exposition about 1956 and ended up purchasing a greenhouse. That’s how the business started. My father Lyle graduated from high school in 1960 and went to SD School of Mines & Technology but came back to grow the greenhouse business after his father died.”
In those days, there were no packs and flats and basket industry, according to Mensch. “No refrigerated trucks or fast airplanes to ship flowers to rural areas. They grew cut flowers for their flower shop. Lyle and local partners tried to grow hydroponic tomatoes but it didn’t last long. Quality of tomatoes grown indoors was the downfall of that project,” he said. Now gardeners can purchase plants at the retail Mensch Flower Shop in Avon run by Mensch’s cousin Carol Tolsma. Mensch Greenhouse, Inc. handles commercial clients.
Asked what his business is known for, Mensch responds, “I’d like to think it’s the overall quality. Twenty years ago, if you had petunias, geraniums, marigolds, and pansies, you had a greenhouse. We’re doing so many different things now. No one major crop is more important than others. Customers tell how beautiful everything is. I see the corner of that tray that needs to be watered. If there are plants we can’t grow right, I don’t want to grow them. Not everything we do here is perfect. I don’t want to pass my mistake on the next fellow.”
What does Mensch like most about his profession as a greenhouse grower? “I can fit all the hell of one year into the first six months.” As soon as this season ends late June, Mensch begins orders for next season. He makes adjustments with suppliers and looks for new plants. He repairs and replaces. He sheds commitments to customers. :”Then the only commitment is to myself. And it frees me up for hunting season.”