Growers looking to keep empty hoophouses productive during the off-season should look no further than the expanding market of fresh greens. This specialty market is keeping houses filled with fresh produce in early spring, late fall and even over the winter, consequently providing an income stream that they typically wouldn’t during that time of year.
“Everything in this area is niche stuff,” says Steven Bogash, horticulture educator at Penn State Cooperative Extension. “Growers provide greens to restaurants, farmers markets, specialty grocery stores [and more].”
The growing methods for these different greens is about as diverse as the markets for the produce. Bogash says he sees greens grown in soil, ground-based beds with potting medium and benches with potting medium — not to mention a whole range of hydroponic methods.
Specialty greens including bok choy, kale, arugula, mustard greens, chards and various forms of lettuce, including mini and regular head lettuce, romaine, leaf lettuce —and even microgreens — are all options.
“Choosing varieties that are suitable for the local market is critical to success,” says Allen Pyle, horticulturist at Jung Seed in Randolph, Wisc.
Iceberg lettuce is still the biggest seller; however, romaine, leaf lettuce and the full- and mini-lettuce varieties are becoming increasingly favored by consumers, particularly in the local market sector, which includes both restaurants and institutions.
Mini head lettuces, such as Rosaine, a red lettuce, and the green Spretnak lettuce can be sold to supermarkets in clamshells and in mix boxes to restaurants, farmers markets and community supported agriculture organizations (CSAs). These lettuces require up to about 52 days to maturity and are suitable for growing in the early spring or fall.
The baby leaf varieties, such as Red Sails and Coastline, are also popular and can be grown and mixed together for a colorful, eye-appealing combo. These are normally cut when still immature so they can be ready for harvest in about half the time it takes to grow full heads.
One new variety of lettuce, Bistro Blend, provides the best of both worlds. It can be grown as a baby leaf and harvested in about 30 days, or grown to full size in about 80 days and sold as a full-size head lettuce.
Also making inroads in the specialty market are microgreens. Growers can get multiple turns from each crop. Most of these speed demons require only 10 to 15 days to mature. Seed catalogs provide pre-mixed combinations of mild and spicy greens, or you can choose from dozens of different greens including dill, radish, mustard, kale, and cress.
Basil and other greens
The field is wide open when it comes to testing the market with different types of greens. Pyle sees increased interest in herbs, such as basil. Other greens that are gaining a foothold into markets include bok choy, kale, parsley, mustard and some of the Asian greens.
“Probably the best option is when you can develop a relationship with a chef,” he says. “That can be extremely valuable. You might try growing some things they recommend or trialing some things you might want them to try.”
Growers are also creating their own signature mix of colors and textures to offer to restaurants and specialty grocery stores. This requires good timing in the houses, which comes with experience. Growing different varieties also reduces the chance of a total crop failure should one variety prove to be susceptible to disease.
At the MSU Research and Extension Center in the Upper Peninsula of Michigan, Collin Thompson, program instructor and farm manager, is proving fresh greens can be grown over the winter, even in the frigid Zone 4 region.
The high tunnel at the research farm produces a nice variety of greens for local markets year-round, but it is their winter growing program that is most impressive. Thompson says they have double poly on their hoophouse and use two layers of floating row cover placed over the crop for extra frost protection in the winter.
The winter season for production of greens starts in about September. Thompson says things like head lettuce are started as transplants, while arugula, spinach and Asian greens are directly seeded. Leafy greens can begin to be harvested in about mid-February by simply clipping off the leaves and letting the rest of the plant continue growing.
“It’s kind of like a bank account,” says Thompson. “We’re taking withdrawals as we move forward in the winter realizing that the varieties we have selected can withstand the temperatures they’re going to see at a mature size.”
Thompson plants in amended soil and adds what’s needed in the soil to make up for deficiencies noted by soil tests. He uses various supplements including rock phosphate, greensand, potassium sulphate and gypsum to adjust the soil. The organic grower relies mostly on fish fertilizers, blood meal, bone meal and kelp meal to feed his plants.
Although Thompson does encounter some diseases and pests in the hoophouses, most don’t stand a chance against the deep freeze of winter.
“We’ve got hard enough winters where things hibernate or die off, which is helpful,” says Thompson.