One Year — One Ton of Fresh Food: Winter Garden Review

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Today’s blog entry is one of a four-post series that highlights my garden favorites over the past year — one post per season. I hope you’ll come back and see more stories from the past fall, spring, and summer, many of which I’ve never shared before, here or elsewhere.

Winter’s Garden

Winter is my favorite season in the garden. I know that sounds crazy and unbelievable — unless maybe you’re a winter gardener, too.

On a mission to harvest dinner (and carrots for the snowman) on February 3, 2013.

On a mission to harvest dinner (and carrots for the snowman) on February 3, 2013.

Don’t get me wrong — I appreciate eating a warm tomato fresh off the vine as much as the next person. But summer is a season of plenty; I can get vine-ripened tomatoes from my neighbors, my farmers market, or at roadside stands up and down our country highways if I don’t have a garden at that time.

If I don’t garden in winter, what fresh produce is available to me? Like most home gardeners and farmers across the country, the folks in my area take a break during the winter. That leaves the area grocery stores as my only option. They have produce from who-knows-where, harvested who-knows-when, and let me tell you… it ain’t pretty.

They're really selling this stuff? Rotten pak choy in the grocery produce aisle.

They’re really selling this stuff? Rotting pak choy and wilted vegetables in the grocery produce aisle.

 

Besides getting nutritious, delicious and inexpensive fresh produce, there is so much more I gain from the garden in winter. In the midst of a frozen and gray landscape, there is green and vibrant life under the protection of the fabric row covers and plastic sheeting in my winter garden. Some varieties even grow completely unprotected from snow and frost. The resilience these plants show to repeated freezing in the night and thawing in the morning sun is inspiring. You can’t help but be an optimist after spending time in a winter garden.

Frost-kissed Joi Choi Pak Choy. January 5, 2013

Frost-kissed Joi Choi Pak Choy. January 5, 2013

There's gold in them thar tunnels! An uncovered bed shows what lies within the tunnels on January 4, 2013.

There’s gold in them thar tunnels! An uncovered bed shows what lies within the tunnels on January 4, 2013.

 

Come before winter…

I also love winter gardening because it is so EASY. As I mentioned in my previous post on fall gardening, the hard work of winter gardening is over by the time winter actually arrives. The planting has been completed by the late summer and early fall, because in my plant hardiness zone (6b), plant growth slows down to a crawl in the winter. That also means that I can look forward to almost three months of no weeding! Since the vegetables are almost fully mature and tightly spaced, they outcompete any young weeds for light. And since temperatures are so cold, the majority of the weed seeds aren’t germinating, anyway. There’s not really much work left to do in the winter garden — except the harvest.

A colorful harvest from the winter garden on January 10th, 2013.

A colorful harvest from the winter garden on January 10th, 2013. Purple and White Vienna Kohlrabi, Bright Lights Swiss Chard, and Carrots (Lunar White, Danvers 126, and Scarlet Nantes)

Winter root crops have become super-sweet, accumulating natural antifreeze in the cold temperatures.

Winter root crops have become super-sweet, accumulating natural antifreeze in the cold temperatures. January 29, 2013

Along with the hard labor of getting a garden established, there are other things missing from the winter garden, too. Insect pests are gone. And as long as temperatures don’t climb too high in the tunnels, so are plant diseases. As I tell participants at my workshops, winter gardening just may be the easiest gardening you’ll ever do!

 

Living Without

Now that we’ve established that winter gardening requires very little energy input from you, let’s go ahead and clarify another thing that isn’t required — you don’t need a greenhouse, supplemental heat, or additional lighting to grow fresh vegetables in winter. That’s right… winter gardening is a zero-energy-input endeavor. It’s all about choosing plants that thrive in cold temperatures to begin with, and then giving them some extra protection from harsh elements like wind, low humidity, frost, and sub-freezing temperatures. If you’d like to learn about over 30 vegetable types you can grow in winter,  check out my list of vegetable varieties and planting dates for winter gardening in zone 6b (updated September, 2014).

Although cold frames have historically been popular for winter gardening, I prefer the flexibility and scalability of inexpensive low tunnels. Low tunnels, called mini-hoops by some folks, are easy to construct, and easy to store when they aren’t in use. They are essentially PVC or metal arcs anchored in the ground and covered with plastic sheeting or fabric row cover. I build 5 ft x 35 ft tunnels for less than $50 each, covers included. If you would like to learn more about how to build one for your garden,  check out this guide on low tunnel construction, or this post if you need pictures of the process.

How much difference in temperature can a layer of plastic provide? As shown in the following chart, it can easily be almost 40° F warmer inside an unvented low tunnel on a sunny winter’s day.

24hourcompare

Now, you might be looking at this chart and thinking, “A low tunnel might warm in the daytime, but the temperatures still dip to freezing at night.” In the example above, the low tunnels provided at least an additional 5° F of protection at night, which was at the low end of the range for the entire winter season. Even though we had many nights in the low teens (° F), the tunnel temperatures never dropped below 22° F at ground level. That may not sound like much, but as you can see in this freeze tolerance of vegetables chart, that little temperature boost means a lot in the plant kingdom.

Freeze Tolerance of Vegetables

But a slightly warmer temperature isn’t the only benefit provided by a tunnel. Think of the mechanics of freezer burn — the dehydration and subsequent oxidation of meat and vegetables stored in your freezer. How do you prevent freezer burn? First, you try to remove as much air as possible from the packaging and seal it well, so that the dry air of the freezer space doesn’t promote evaporation of frozen water from the food (i.e., sublimation). Alternatively,  you can increase the humidity in the freezer environment, such as by leaving open containers of water in your freezer. Low tunnels do a little of both for your plants, effectively increasing the humidity around the plants to inhibit sublimation of water from plant tissues, and also “package” the plants away from the drying effects of wind. After all, the greatest damage to cold-tolerant plants is not freezing per se, as they have adapted to deal with that, but desiccation (which is why frozen plants go limp and then perk up again once they warm later in the day, and why freeze damage is more severe on windy days than calm). Because of the additional humidity and protection afforded by my low tunnels, I’ve had lettuce, chard, and mustards that survived temperatures in the low 20s in the tunnel, when their unprotected counterparts kicked the bucket earlier in the season at higher temperatures. So, although the temperatures in the above chart are good guidelines, they’re not absolutes — low tunnels and cold frames can give you a lot more wiggle-room with a plant’s temperature limit.

These lettuces were direct sown in a low tunnel on November 6, germinated, and grew slowly all winter. Here they are March 6th -- they're now large enough for salads at the time everyone else is sowing their spring lettuce beds.

These lettuces were direct sown in a low tunnel on November 6, germinated, and grew slowly all winter. Here they are March 6th — they’re now large enough for salads at the time everyone else is sowing their spring lettuce beds.

Although much more cold-tolerant than lettuce, this unprotected kohlrabi is has "freezer-burn" on February 5th. Protected kohlrabi in the tunnels had no such damage.

Although much more cold-tolerant than lettuce, this unprotected kohlrabi has “freezer-burn” on February 5th. Protected kohlrabi in the tunnels had no such damage.

 

A Winter’s Harvest

I harvested over 150 pounds of fresh produce from our low tunnels between December 21, 2012 and March 20, 2013. Combined with the over 100 pounds of produce that we had harvested since November 1, 2012, that amounted to over 250 pounds of FRESH vegetables grown in the agricultural “off-season.” Not bad, considering that only about 1/3rd of our tenth-acre garden was in production, as the remainder was planted in winter cover crops.

winterharvest2013

At this point in today’s post, I’m turning it all over to pictures — I know you want to SEE all of this beautiful winter produce, right? Before I let the images speak for themselves, allow me to give a shout-out to the individual that inspired it all: Eliot Coleman. Mr. Coleman’s books provided the background and practical knowledge that I needed to begin learning how to grow my family’s food in winter. Although we’ve never met, I will forever be appreciative that he shared his experience and production techniques in his books. Although I hope you can get a good start in winter gardening through this blog, I highly recommend that you read Mr. Coleman’s book, “Four-Season Harvest,” which is frequently available in public libraries across the country (or thank him as I did with your purchase of it).

Winter Garden Images

The garden under snow on February 3rd.

The garden under snow on February 3rd.

Although the main broccoli heads had been harvested in fall, side shoots remained harvestable through mid-January with occasional protection from fabric row cover.

Although the main broccoli heads had been harvested in fall, side shoots remained harvestable through mid-January with occasional protection from fabric row cover.

Baby michihili cabbage and kale frozen in the early morning on January 5th, 2013.

Baby michihili cabbage and kale frozen in the early morning on January 5th, 2013.

Once temperatures warm, the same chi chi cabbage and kale have perked right up. This tunnel was protected without plastic all winter -- just an Agribon-30 row cover was enough.

Once temperatures warm, the same chi chi cabbage and kale have perked right up. This tunnel was protected without plastic all winter — just an Agribon-30 row cover was enough.

Most of our winter salads were this delightful mix of baby kale, tatsoi, michihili cabbage, and cress.

Most of our winter salads were this delightful mix of baby kale, tatsoi, michihili cabbage, and cress.

Rapini (broccoli raab) harvested for dinner on January 14th, 2013.

Rapini (broccoli raab) harvested for dinner on January 14th, 2013.

I worry more about temperatures getting too high in the plastic-covered tunnels than too cold. This endive has bacterial rot in the center, promoted by temperatures in the tunnels that climbed to 81 degrees F while I was gone on vacation and unable to vent.

I worry more about temperatures getting too high in the plastic-covered tunnels than too cold. This endive has bacterial rot in the center, promoted by temperatures in the tunnels that climbed to 81 degrees F while I was gone on Christmas vacation and unable to vent them manually.

Luckily that same endive recovered. Here it is on March 19th, 2013.

Luckily that same endive recovered. Here it is on March 19th, 2013.

This was a popular image that I shared on the Mother of a Hubbard Facebook page, illustrating the diversity of greens possible, even in winter.

This was a popular image that I shared on the Mother of a Hubbard Facebook page, illustrating the diversity of greens possible, even in winter (January 15, 2013).

Heading varieties of Chinese cabbage look so cool in the garden, although the outer leaves are more susceptible to freezing than European varieties. January 5, 2013

Heading varieties of Chinese cabbage look so cool in the garden, although the outer leaves are more susceptible to freezing than European varieties. January 5, 2013

Duck photobomb

Duck photo-bomb. February 3, 2013

January 29th. Bright Lights swiss chard, spinach, and other veggies are looking great in the tunnels.

January 29th. Bright Lights swiss chard, spinach, and other veggies are looking great in the tunnels.

Removing the covers on a warm February 26th -- the tunnels are growing progressively thinner from the harvests.

Removing the covers on a warm February 26th — the tunnels are growing progressively thinner from the harvests. More weeds are beginning to appear as a result of warmer temperatures and fewer plants, but they aren’t impacting vegetable growth.

Spring has already arrived in the tunnels on March 4th, as evidenced by this arugula blossoming.

Spring has already arrived in the tunnels on March 4th, as evidenced by this arugula blossoming.

caption this

“Hey! When she turns away, let’s just duck under that fence.” (Thanks, Vicky, for the caption suggestion!) Haul from the garden on March 4th, 2013.

Not broccoli raab... kohlrabi raab! If you think your kohlrabi or kale is done when it bolts, you're wrong. I prefer these to broccoli raab.

Not broccoli raab… kohlrabi raab! If you think your kohlrabi or kale is done when it bolts, you’re wrong. I prefer these to broccoli raab. Harvested March 13, 2013.

Starting seeds of the summer crops. March 18, 2013.

I love winter crops, but still have to plan for summer. Starting seeds of the summer crops under grow lights, March 18, 2013.