The Results Are In: Winter Lettuce Trial at DFI

As the summer months start to fade into memories here in Northern Nevada, many of us begin to long for the days of fresh salads made from veggies grown right here on the farm. 

That made us think. In a high-desert climate like in Reno, would it be possible to grow a consistent, quality crop of winter lettuce? With the help of a Specialty Crop Block Grant from the Nevada Department of Agriculture, we conducted a winter lettuce trial at the Desert Farming Initiative to find out. 

The results may not be a total surprise. After trialing different growing techniques, varieties, and planting dates over the course of several growing seasons, DFI concluded that growing lettuce for winter harvest and/or producing lettuce throughout the winter season for spring harvest in Northern Nevada comes with many challenges for commercial production and is not recommended. 

There are, however, some opportunities to successfully grow winter lettuce crops with appropriate climate control mechanisms, such as producing lettuce hydroponically, in a heated greenhouse or heated hoop house. Producing lettuce in a non-heated hoop house (like the ones at DFI) through the winter can be a hit or miss prospect depending on the low temperature extremes during a particular season, but extreme nighttime lows will damage lettuce grown in hoop houses. 

Humidity levels will also likely be high in a hoop house throughout winter which may increase fungal diseases such as botrytis crown rot. Insect pressure is greater in hoop houses earlier in spring and often begins in late winter, therefore more pest management should be expected.  Managing a lettuce crop clean of disease or pests, especially organically, may require an intensive pesticide application program, if producing lettuce for wholesale.  

Home gardeners can still have fun with lettuce production throughout the winter – there is still good harvestable product for the dinner plate. Growing food for self-consumption in the garden does not come with the risk of producing food for income.  

Some other key takeaways:

  • Producing lettuce in the field for winter harvest is not recommended for commercial production in Northern Nevada climates.
  • Low temperatures in the winter will damage the leaf tissue in the field and potentially in a hoop house as well.
  • Unpredictable and very low temperatures in Fall jeopardize the quality of field grown lettuce due to frost damage. (Quality can be acceptable for direct to consumer markets such as farmer’s markets or CSA, and in the home garden).
  • The utilization of row cover in the field does not improve growing conditions enough to produce a quality product. In addition, more labor is required to maintain the row cover.
  • Mature lettuce, such as a developed head lettuce is more susceptible to freezing temperatures than young baby leaf lettuce.
  • There is potential to produce quality/ sellable loose leaf or baby leaf lettuce throughout the Winter season in hoop houses. However, an Integrated Pest Management and preventive pesticide program should be implemented.
  • The success of winter lettuce production in the hoop house may be very dependent on the lettuce variety. Multiple varieties should be trialed in your farm and garden to find the best option. For example, Oakleaf varieties were most susceptible to botrytis crown rot in our trials.
  • The utilization of row cover in the hoop house is critical for added protection against extremely low temperatures.
  • Insect and fungal disease pressure is greater in hoop houses and can damage a crop leaving it not sellable. 
  • Planning for mid- to late-fall harvest is more realistic in Northern NV, for both head lettuce and loose leaf. 
  • In Northern Nevada, there is not much opportunity for a winter field lettuce industry, however, Southern Nevada climates may be suitable.
  • Producing lettuce on small commercial farms is likely most profitable during the late spring – early fall harvest season.

Read the full report, complete with details on the trials conducted and results, on the DFI projects page. If you have any questions or would like to request additional information, please contact Charles Schembre, DFI Program Manager, at cschembre@cabnr.unr.edu

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