Winter (Greens and Cover Crops) is Coming

Monday, August 14, 2023

For those of you who anticipate winter greens production in your greenhouse rotation, now is a great time to make sure that you have your plan in place! Seeding date is crucial for plant establishment into the fall before light levels drop below critical values. Below is an example of the time to harvest for three different winter greens, and their corresponding planting dates. While these are not set in stone, and success is going to vary year to year based on climatic conditions, it demonstrates the impact that lower light conditions have on ready-to-eat winter greens:


  • Planted September 19 --------> Harvested November 5
  • Planted October 25 -----------> Harvested February 19
  • Planted September 22 --------> Harvested October 29
  • Planted October 26 ------------> Harvested February 12
  • Planted September 22 --------> Harvested November 19
  • Planted October 21 ------------> Harvested February 19
Consider the value and health of your summer cash crops when deciding which is going to make more sense for you going forward. Split seeding dates can be an effective strategy to try and get the best of both worlds, as suggested by David Blanchard in his two-part series presentation for the original 'Getting Into the Weeds' series. Anyone who is considering, or currently producing, winter greens production should check out this session! He goes into his experience growing certain types of greens, the pros and cons of different tunnel structures, and how to buffer against cold temperatures with relatively little input from supplemental heating.

                    Winter Greens Production Part 1 - Watch Here!

                    Winter Greens Production Part 2 - Watch Here!

Along that same vein, those of you who are considering implementing cover crops in protected spaces should start thinking about the plan for the upcoming season transition. Cover crop establishment is highly dependent on seeding date, alongside making sure the crop has sufficient water to germinate, and is seeded appropriately. Below is an image of a seeding date trial for a tillage radish+ oats mix implemented in 2022-2023. The greenhouse was subdivided into 4 sections, with the first planting date happening mid September shown on the far left of the image. Each of the remaining sessions were planted on a weekly basis, with the final planting date taking place mid October (far right of the first image). The amount of above-ground biomass is significantly different depending on planting date, with higher amounts of plant tissue in the early seeded treatment compared to the later one. More biomass translates to more organic matter generation in the space, which can in turn contribute to healthier soils and improved nutrient banks for next years crop. You can see a close-up of the density in the early planted cover crop on the right hand image below.

For more information on cover cropping in protected spaces, check out our session with Judson Reid from March 2023, where he discusses basic timelines and practices that will optimize cover crop performance indoors.

                    Cover Cropping in Tunnel Spaces - Watch Here!

As always, don't hesitate to reach out to our Protected Crop Specialist for all winter-greens production questions.

Posted by: Talia Plaskett