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Cold Frame in the snow - Woodman

Extending the Harvest in Your Home Garden

Grow year-round with these simple methods
Tuesday, January 25, 2011, 7:05 PM

One way to improve resiliency as well as quality of life is to grow your own vegetables locally. However, gardeners in northern climates are especially challenged by limited growing seasons. In this brief article I will show examples of how to easily extend and preserve the harvest and have fun doing it.

Why Extend Your Harvest?

Presently we can drive to the supermarket to get nearly anything we want even in winter. The fresh fruits and vegetables we see have often been grown thousands of miles away in a tropical climate and flown in using a lot of energy may not be so cheap or plentiful in the future. As well as potentially reducing dependence on energy, extending the harvest of your own foods has advantages including:

  • Less work and simpler than preserving by canning or freezing
  • Fresher, higher quality than canned
  • Less expensive than supermarket
  • Increased resiliency with the option to of a local food source
  • Controlling your own food sources is more pleasurable and rewarding

All these pluses for extending your own harvest can add up a higher quality of life. You may not meet your major calorie needs (that is probably better done with stored grains and potatoes), but you’ll have a source near your doorstep of fresher, vitamin-rich greens to round out your meals.

In the summer of 2008, I was already putting attention back into a neglected backyard garden from earlier years, when I stumbled on to the concept of Peak Oil and the need to adjust my lifestyle. Unfortunately, the initial garden was a complete disaster, mostly resulting in raised beds of massive weeds. Clearly I still had a lot to learn , but nearing the end of August in New England left me little time to salvage the season. Fortunately, I found Eliot Coleman’s book Four-Season Harvest. I used ideas from this book, plus Square Foot Gardening methods for organization, to get much improved results before the end of that year.

How to Extend the Harvest

Some principals of extending the harvest include:

  • Adapt to your climate
  • Plant vegetables successively
  • Choose hardy crops for cold weather
  • Protect your crops with simple devices like cold frames.
Adapting to Your Climate

The idea is to not fight your climate during the cold seasons with expensive heated greenhouses and growing lights. Instead, get to know your local climate! For example, when is your first frost date in the fall? At my house, the first hard frost came on October 11 in 2009 and on October 18 in 2010. Then use the other principals above to adapt to the climate you have. 

Succession Planting

Planting vegetables at intervals from spring to summer to fall extends the harvest of fresh vegetables as much as possible. As your vegetables mature, they can be harvested as you need them. This avoids the need for larger time investments to preserve large batches of food that mature all at once.  As the fall approaches, you will transition to hardier crops and crop protection.

Choosing Crops for Cold Weather  

Coleman’s book has lots of great information on which vegetables do well in cold weather and when to plant them. My favorites that I have been able to carry right into December in cold frames include:

  • Lettuce
  • Spinach
  • Parsley
  • Scallions/green onions
  • Chard
  • Tatsoi
  • Claytonia (miner’s lettuce)
  • Mache/corn salad

Other common veggies that not only tolerate but can thrive in cooler seasons include:

  • Carrots (especially the Napoli type)
  • Beets
  • Peas
  • Broccoli
  • Turnips

Some of the hardiest cold weather greens that I had never heard of before reading Coleman’s book include Claytonia, Mache, and Tatsoi. They are also much tastier than iceberg lettuce from the supermarket and richer in vitamins.

Plant seeds for the veggies you like to eat and skip the rest.  Other sun-loving vegetables like tomatoes and corn are best enjoyed in season and preserved for the rest of the year.

Managing the Extended Harvest

Coleman states in his book that this innovative thinking involves realizing that only the harvest season and not the growing season needs to be extended. The idea is to grow vegetables during the warmer seasons, hibernate them during colder, dormant seasons, and harvest as needed.

Carrots grown in the heat of summer, for example, just don’t seem to taste good if not promptly harvested when matured. But I’m amazed at how long they last in the fall when kept stored in the garden bed. The trick is knowing your climate and getting the timing right. In 2009, I found that carrots planted the end of August did not mature in time before winter, but this year I was on the ball and had a large crop from seeds sowed August 1. The carrots were kept in raised beds under cold frames right up until the risk of the ground freezing was imminent. Then I pulled most of them in late October and stored them in the root cellar. Those carrots are still fresher tasting than the ones from the supermarket, which only seem to last a week or two at most in the refrigerator.

Greens like spinach, chard, and lettuce are not really for storage, but can handle a few freezes, especially if protected in a cold frame. The best way to harvest is to take a few leaves at a time as you need them. While the water is coming to a boil on the stove for pasta or potatoes, I go out at night with a headlamp and snip what I need for the evening with scissors. 

While the hardy winter greens can usually tolerate freezing while they are still rooted, they will not be very palatable if harvested while freezing. Except for mache, tatsoi, and scallions, wait until the temperature rises above freezing before harvesting. 

The photos below show some lettuce (Winter Density) that I harvested on January 1 this year after shoveling snow off the cold frame.  Temperatures the previous week had dipped to 15F at night outside, but a warm day allowed me to get a fresh salad 20 feet from my kitchen.

 

I’ve noticed some overwintered plants do much better than seeds planted in early spring. For example, spinach planted in the fall in my cold frames will carry on until about December, then re-appear with vigor again around March as the days grow longer again. Those same plants will produce leaves until hot weather in June when they bolt and go to seed. Then it’s soon time again to plant more and repeat the cycle. You can also get a jump start in spring by planting some spring crops in the cold frames as soon space opens up from harvesting fall and winter crops.

Cold Frame Construction

Cold frames are a simple, low-cost alternative to greenhouses that let light in, help contain heat from the earth below, and protect vegetables from harsh conditions of cold temperatures, wind, rain, and snow. Basically, a cold frame is a box with a hinged transparent top known as a "light." There are a number of options to use to construct cold-frame lights, including old windows, sliding glass door panels, plastic sheeting, acrylic sheets, and corrugated polycarbonate panels. They can work well in conjunction with raised beds. Be cautious, though, about the potential dangers of broken glass.

I’m always on the lookout for old windows and glass doors by the curb on trash pickup day, and have accumulated a collection out back. Below is a photo of a 3’ by 6’ raised bed covered with a double-pane patio door that my neighbor was throwing away. After he saw what I did with it, he wished he had kept it!

The best location for your cold frames is close to the house and facing south. The handier they are to your kitchen, the more likely you are to go out to harvest something, rather than just reaching into the refrigerator. I have some frames right in front of my house next to the driveway in a sunny spot, and interested passer-bys often stop to ask what is growing in there!

The sides of the cold frame are made from 2” thick spruce planks screwed together with deck screws and the light is secured with some old hinges. A slope of about 1” vertical to every 12” horizontal seems to be about right. 

I’ve also made low tunnels or hoop houses with ½” PVC pipe and polyethylene plastic sheeting. This allowed me to size the tunnels to match existing cold frames that were too big for patio doors or windows. Disadvantages are that the plastic sheeting is not as durable or as insulating as glass and wood.

Prefabricated cold frames can also be purchased, but they are generally beyond my budget. Check some out, though, if you need some design ideas. 

Cold Frame Management

The two most important things to control in managing your cold frames are temperature and water. On sunny days, the temperature in a cold frame can become like a sauna. You will need to be sure to provide enough venting during spring and fall when the sun is higher. I keep sticks of various sizes handy to prop open the cold frame lights as necessary. In winter, no venting may be necessary at all. If in doubt, erring on the cool side is better than the risk of cooking your veggies. 

Much less water is needed during the cooler months since there is less evaporation. Once in a while I’ll add a little water gently on a sunny day so the leaves can dry off before evening. In winter there is no need to water at all.

Resources

A short list of resources is provided I have found helpful and that will link you to more sources of information if needed. Also search online for “cold frames” and you’ll find many more ideas for construction.

Related content

9 Comments

EndGamePlayer's picture
EndGamePlayer
Status: Platinum Member (Offline)
Joined: Sep 2 2008
Posts: 546
Re: Extending the Harvest in Your Home Garden

Woodman -

You have inspired me wih all your hot talking about cold frames and fresh food now in the middle of winter! With a little luck - next year this time I'll be munching on a tasty kale or colorful swiss chard salad with the winter soup.

EndGamePlayer

joemanc's picture
joemanc
Status: Martenson Brigade Member (Offline)
Joined: Aug 16 2008
Posts: 834
Re: Extending the Harvest in Your Home Garden

Excellent Writeup! I hit the Print button as soon as I finished reading. Looks like I'll have to keep an eye out for some old windows.

pinecarr's picture
pinecarr
Status: Diamond Member (Offline)
Joined: Apr 13 2008
Posts: 1607
Re: Extending the Harvest in Your Home Garden

Woodman, what great information!  Thank you so much!

CAH's picture
CAH
Status: Bronze Member (Offline)
Joined: May 29 2009
Posts: 62
Re: Extending the Harvest in Your Home Garden

Woodman -- great article!  I have been planning to get some cold frames up and going this year, and your article provides me with some inspiration to do so!

I've also come across another interesting idea of how to extend the growing season for warmer-weather vegetables using a trellis frame.  The article and pictures on how to build the frame can be found here: http://www.grit.com/Do-It-Yourself/Garden-Trellis-Design-and-Constructio...

The basic idea of extending the season with the trellis is since the trellis frame has a "box" on all sides and the top, you take clear plastic sheeting and put it over your tomatoes, cucumbers, or any other warm-weather climber before the first frosts.  That way, so long as you don't have a hard, deep frost, the plants stay alive and can continue producing well past the end of the normal season.  I'm building some similar trellises as those in the article for my garden this year, and can't wait to see how long I'll be eating fresh tomatoes into the fall!

ON EDIT:  I also have a shed FULL of old storm windows taken from "dumpster diving" waiting to be used on cold frames.  My wife thinks I'm crazy for keeping them around.  Now I have proof that I'm either not the only crazy person out there, or I've stumbled into an island of sanity on this site (I think it's the latter).

dcm's picture
dcm
Status: Silver Member (Offline)
Joined: Apr 14 2009
Posts: 117
Re: Extending the Harvest in Your Home Garden

Good Stuff Woodman

Coleman is definitely the pioneer in this area, and, like Chris, a great speaker. Here is a PDF of a good earlier article

http://www.fourseasonfarm.com/pdfs/garden_for_all_seasons.pdf 

His most fundamental point is our lattitude, we get plenty of winter light compared to upper europe. I'm in Seattle which is warmer but still three degrees north of coleman's location but I have still been able to work his techniques through winter. Home Depot carries a relatively new product which is fantastic for building a greenhouse or box. It is nearly indestructable and lets in 98% of the light. It is about $22 for an 2 1/2 ft by 8 ft panel. Not cheap but the stuff will last forever. I have built an 8 X 8 greenhouse with it and redwood and am very pleased. It also cost me $1000 less than buying a comparable greenhouse.  

Another great book is Perennial Vegetables by Eric Toensmeir. Perennial vegetables are definitely resource and energy efficient. I have also found that many Asian greens have some excellent winter tolerance.  These guys are a great affordable source

http://www.evergreenseeds.com/vegetableseeds.html

Arugula is definitely outstanding and sprouts quickly. I just seeded some last weekend and they are already up!  Kale is exteremely tolerant as well (and incredibly good for you) These folks have cross bred a very tolerant strain

http://www.adaptiveseeds.com/node/22

As woodman indicates, it is all about the timing and that comes with trial and error however I was able to find at least two bloggers in my location who had been practicing this for a while and had great suggestions on planting times. I have also found, at least at my lattitude, that by the third week of January, the plants begin to start responding to the growing light. You can then start to reseed some of the more tolerant and fast growing greens and radishes       

A. M.'s picture
A. M.
Status: Diamond Member (Offline)
Joined: Oct 22 2008
Posts: 2347
Re: Extending the Harvest in Your Home Garden

This is awesome - excellent work Woodman!
Cheers!

Aaron 

Travlin's picture
Travlin
Status: Diamond Member (Offline)
Joined: Apr 15 2010
Posts: 1322
Re: Extending the Harvest in Your Home Garden

A very informative and well written article Woodman.  I've been following your gardening through the threads and this brought it all together.

Travlin 

Poet's picture
Poet
Status: Diamond Member (Offline)
Joined: Jan 21 2009
Posts: 1844
Gentle Slopes And Walls For Solar Gain

Excellent article! I second the recommendation on Eliot Coleman's book, The Four Season Harvest.

I believe in that book, Coleman also mentions the advantages of planting on a south-facing slope and next to a south-facing wall.

There is a gain of solar energy received to the soil due to the angle (just as one would get with an angled solar collector or cold frame glass.

Also, planting south of a light-colored south-facing wall helps take advantage of heat and light reflection from the wall, and the thermal mass of the wall releasing warmth after the sun is down. (I'm sure being a wind break against winds from the north and cold seeping downhill will help as well).

Apparently together, they're enough to lower the lattitude of the planted location by a few hundred miles.

Poet

grandefille's picture
grandefille
Status: Bronze Member (Offline)
Joined: Oct 11 2010
Posts: 30
Re: Gentle Slopes And Walls For Solar Gain

Last weekend I attended a FANTASTIC seminar about season extension, as part of the Northern Michigan Small Farm Conference.  The presenter lives along the shore of Lake Michigan, in Zone 5. Among other things, he grows tomatoes from seed and harvests heirlooms in late May, a full two months ahead of "normal" tomato season here; and does this with NO supplemental heating.  He heavily credited Eliot Coleman's season-extension techniques, and has made additional improvements.  Most of his plants are started in a plastic hoop house with additional protection.  Some examples:

-- take a (non-perforated) black plastic tile, fill it with water, and lay it along the row of plants.  Black absorbs heat from sunlight, and warms the plants at night.

-- fill a clear glass jar with red-colored water, and set it next to a plant.  Water absorbs daytime heat, and the red color has been shown to improve tomato plant growth

-- with both of the above techniques, place a blanket of floating row cover over the plants and their "warm cuddly" at night.

-- save open-pollinated seeds, and select for the plants which perform best in his unheated conditions.

I'm going to start a few seeds soon, and give these a try.

Julie

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