The goal of the grant is to determine some parameters for production like what's the yield between the caterpillar spaces and the high tunnel spaces? What is the nutritional quality of the greens that we have cut and then stored in the cooler and then sent the lab.. er.. the samples into the lab?  What's the nutritional composition of greens that we've just harvested fresh?  Then what's the nutritional content of the greens we've harvested, stored for a month, then sent those samples into the lab?

So we plant them in late August and early September.  Get them irrigated.  Get them germinated.  And then ultimately get them really exposed to the first round of really hard frosts.  And then at that point, they develop more of a hardiness and we're able to finally put the caterpillars on top of them.  We might even sneak row cover onto them to get them even more exposed to cold temperatures before we put on those "warm suits".

And then once we've got them good and acclimated to the real shit that's going to come in December... then in November we'll put the ground stakes out, the hoops, the plastic on top, and they (greens) are ready to go.

And what we observed through the process of the grant is that there are only several types of greens that will thrive with that kind of management.  In the process of trialing different greens in those spaces with that strategy of planing them and exposing them and covering them eventually... the mustards didn't pan out all that well... the spicy greens species that we were growing... the yield wasn't very high compared to things like spinach and baby kale and chard.  Basically at this point it's just spinach (we plant a lot of).

Unlike a greenhouse where you plant and you don't have control (over growth rates), where it's really warm in the fall, it's going to heat up, and you're going see growth rates go through the roof, whereas with these temporary structures what we've realized just thinking for the grant and comparing the structures and their benefits and their drawbacks... this (temporary caterpillar tunnel) we can put up anytime.  And either speed up the growth or hold back (the installation of the structure) and just let them basically operate at 50 degrees and they grow really slow at that temperature range.  And also they are way heartier than the (plants) in the high tunnels that have been babied more or less.

Because what we have been noticing also is that once you have conditioned these greens in the cold temperatures they're almost primed for refrigeration and storage.  But we have a question about whether the nutritional content degrades over that time.  Is it robbing Peter to pay Paul?

(Narrator asks) And so what are those results you found?

Some of the key findings were:
Different structures require slightly different seeding dates for maximum production and minimal crop loss.  Seeding in the field and building a temporary caterpillar tunnel allows for earlier seedings (2-3 weeks earlier) because the heat units don't create the conditions for quick growth in October and November.  Tunnel seedings need to be delayed so leaves don't get too big and susceptible to hard frosts.

Some plant species (mustards, brassicas, and many lettuces) are too frail for reliable winter production in our climate, regardless of whether they're grown in high tunnels or caterpillars.  It's not that they don't produce food; it's that the time it takes to harvest makes growing and protecting these greens unprofitable compared to other greens like green spinach, red spinach, chard, kale, claytonia.  A winter production farm only has so much time to harvest during thawed windows of time.  This scarcity informed a study design change between the winters of 2019-2020 and 2021-2022.  Our data collection scope shrunk so that we could answer questions related to different spinach varieties seeded at different time periods in these different structures. 

Mustards grown in high tunnels and caterpillar tunnels were far less productive than spinach unless these mustards get harvested before single digit outdoor temps (typically before December).

Spinach yielded best (.150-.158 pounds per foot) when the following criterion was met:
-seeded at the optimal periods for their given structure (hightunnel or caterpillar tunnel)
-exposed to frigid temps when outdoor temps dropped into the teens and single digits under 1 layer of row cover,
-covered with additional row covers as outdoor temps moved into the negative degrees
-minimal/no eating damage from voles, mice, shrews, and pocket gophers

Yield of spinach seeded too early and minimally protected (0.06lbs/row ft) appeared just as unproductive as highly protected spinach that is eaten by rodents (.02lbs/row ft).

Our analysis of spinach after storage was that:

No spinach from samples harvested on 1/26 and stored through 3/2 was discarded after this long-term storage.  It was all deemed high-quality visually after this storage period.  There were no signs of yellowing or dehydrations.

For future samples, we recommend using NP analytical for nutritional testing.  They are willing to measure time-sensitive samples the morning after they're shipped overnight to them.

Vit C and folate dropped significantly which our consultant, Wan-Yuan Kuo, said was to be expected.  She said just 15 days can drop Vit C, so the 6 day delay might already drop vit C

Vit A seemed increase slightly (can’t be sure if all data was measured with one replication), which may be due to moisture loss or postharvest biochemical synthesis 

Vit K did not seem to drop significantly.  And, unlike the other nutrients, the results of Vitamin K did not draw a comment from Wan-Yuan Kuo, Ph.D