Trial Criteria for Greenhouse & Hoophouse Varieties
What Makes a Variety Right for Protected Culture?
High tunnels, low tunnels, and greenhouses are sprouting up on farms and homesteads everywhere, as more growers discover the many advantages of protected culture. The benefits of growing under cover include season extension, better crop quality, and protection from bad weather and certain pathogens, such as early and late blight.
Growing in a protected environment does, however, carry its own set of challenges, including an increased risk of diseases specific to greenhouses, such as leaf mold. Crops need to do particularly well to deserve a position in the valuable real estate of a tunnel or greenhouse.
Johnny's Selected Seeds is committed to breeding, testing, and selecting crops that are well-suited to protected culture. In this article, we'll tell you a bit about how we identify these varieties, then provide some recommendations for the ones we think will perform well in your high tunnels, low tunnels, or greenhouses.
Above & Beyond Flavor — What We Look For
Johnny's research department conducts variety trials at our research farm in Albion, Maine, in cooperation with growers and university researchers around the country, and in select locations globally.
This year, for example, Johnny's staff trialed 85 varieties of tomatoes in unheated high tunnels at the research farm. Trialing involves evaluation of a specific set of criteria, including appearance, size, shape, flavor, harvesting for yield data, and plant health, as well as any additional observations of note. To identify the best varieties for heated greenhouse production, we typically find commercial growers who have a market for the crop and work with them to trial new varieties. That way, we gather feedback on both production and marketing from multiple locations around the globe.
What are we looking for when we trial varieties in protected culture? Above all, we want varieties that taste good. Beyond that, we identify a variety as a good choice for protected culture for one or more of the following reasons:
Our Protected Culture Symbol
Once a variety has proven itself in Johnny's trials, it is designated by a red "protected culture" symbol. Look for the symbol next to the variety name in our catalogs and on our website.
Our protected-culture offerings include vegetable, herb, flower, and fruit varieties specifically bred, trialed, and selected to make the most of your valuable undercover, greenhouse, or hoophouse real estate. In this next section, we give some specifics about our current recommendations for protected culture.
Top Crops for Protected Culture
Tomatoes for Protected Culture
Tomatoes are one of the most popular crops for high tunnels and greenhouses. They will produce earlier and later in the season than field crops. Quality is generally much better than field-grown because they are protected from weather-related damage (such as splitting or diluted flavor from heavy rain), which results in higher marketable yields. Additionally, protected culture provides some protection from diseases caused by wet foliage such as early and late blight.
The high-temperature, high-humidity environment, however, is conducive to a different set of diseases — including leaf mold, powdery mildew, fusarium crown and root rot, corky root rot, and botrytis.
So, when choosing tomato varieties for protected culture, Johnny's looks for these three primary factors:
Cucumbers for Protected Culture
Cucumbers are another top crop for protected culture, providing a respectable return on the investment required. The desirable attributes we seek in high tunnel and greenhouse cucumbers include:
Lettuce & Greens for Protected Culture
The cool temperatures and low-light conditions typical within the winter greenhouse or high tunnel can lead to disease, especially downy mildew, and loss of color in red lettuce varieties.
Flowers, too, are a high-dollar crop, especially when they can be available for popular floral events such as Easter, May Day, Mother's Day, graduations, and June weddings. In most locations, field-grown flowers are not ready that early, so high-tunnel and greenhouse production is essential.
Although nearly any flower can be grown in protected culture, the best choices are varieties that yield a large number of stems per square foot of the valuable space. They should be able to tolerate both the cool temperatures of early spring and the hot temperatures of the late spring and summer high tunnel. Finally, they should be day-neutral varieties, which bloom regardless of day/night length.
Our Protected Culture Commitment
At Johnny's we breed, trial, and select for the best genetics possible, in order to offer greenhouse growers the most reliable varieties to commit to the limited available real estate given to protected cover.
You can be confident that we assign our Protected Culture symbol to only those varieties we've carefully trialed and subsequently identified as best suited for the protected culture environment.
Learn more from the following additional resources.
- Why Grow in a Greenhouse? — Greenhouse Growing Basics »
- Browse All Protected-Culture Varieties »
- Trellising Hoophouse Tomatoes »
- Grafting Tomatoes (PDF) »
- Grafted Tomato Yield Data (PDF) »
- Indeterminate Tomato Comparison Chart (PDF) »
- Determinate Tomato Comparison Chart (PDF) »
- ROI for Greenhouse Cukes »
- Cucumber Pruning Video »
- Cucumber Pruning & Trellising (PDF) »
- Cucumber Types & Terminology (PDF) »
- Protect Your Investment — Grow Fruit Under Cover »