Florida growers utilizing protected culture, including high tunnels and open shade structures, have the ability to extend the in-ground season for spinach planting and harvesting times. According to an “Evaluation of Five Spinach Cultivars in Soilless Culture Under High Tunnel versus Open Shade Structures,” a research study funded from the Florida Department of Agriculture and Consumer Services Specialty Crop Block Grant, Florida has significant potential for increased hydroponic crop production due to its mild climate, long growing season and proximity to large markets. However, the mild climate also presents the challenges of high pest pressure, high humidity and high temperatures.
The preliminary results of the study explain the need, as voiced by growers, for better adapted varieties and new crops that can expand the marketing opportunities and extend the production season.
“This current grant project provides us an opportunity to take a look at specific varieties of a number of different leafy greens,” said Bob Hochmuth, regional Extension agent at the Suwannee Valley Agricultural Extension Center. “So, for instance, we have been running variety trials for spinach, kale, lettuce, Swiss chard and the Asian leafy greens group. What we’re able to do there is to take a specific evaluation of those varieties under protected agricultural conditions. Traditionally, a lot of our research is based in open field systems for our larger commercial farms. But the answers that we might find for an evaluation of spinach in an open field might be very different than what we would find for our protected agriculture systems like greenhouses, high tunnels and open shade systems. So, we want to be able to give the farmers who are using those kinds of structures (and perhaps using hydroponic systems) the best answer that we can in terms of which varieties of spinach, kale and other leafy greens would perform the best for them under those conditions.
“We’ve been evaluating spinach in what we call an open trench system, and that’s a situation where we basically dig a ditch in the ground, underneath a high tunnel. And then we line it with nursery cloth material, and then pack full the trench with composted and aged pine bark. We’ve been able to alleviate a number of insects and disease problems, and root-knot nematodes in particular, by going into that system. Those kinds of pests are happy in our Florida sands, but are not very able to reproduce in the composted pine bark. So we sort of have been able to reduce our pesticide use by going to that system underneath the high tunnel. It’s been very successful. We’re still using hydroponic nutrient solution to grow our spinach in that particular case. So it’s been really an innovative way of managing some problems that we would normally have if we were growing straight in the soil.”
Hochmuth also explained that the high tunnel eliminates rainfall from going directly onto the crop, so it stays drier and eliminates a lot of disease pressure.
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