Winter Gardening in Michigan Experiment & 38 Vegetables to Grow in a Zone 5 Winter

This winter, I decided to try growing food outdoors in a cold frame for the first time.  I was inspired to do this by the gardening shows, books and you-tube videos that I've been viewing lately. These included: Elliot Coleman, Alberta Urban Garden, Gardener's World, and One Yard Revolution, among others. Based on watching these folks talk about their gardening experiences, I developed the following...

NOT-SO-SCIENTIFIC WINTER GARDENING EXPERIMENT:

HYPOTHESIS:

 If vegetables can be grown in the middle of freakin' Alberta in the middle of the winter, surely I can grow them here in southern Michigan! (Granted, I've never been to Alberta, but I have been to Quebec, and I can safely say that Canadian winters are no joke: they are coooold!  If the plants can deal with that climate, they should be able to deal with this one, right?)


 

METHODS:

Store-bought cold frame

 I set up 2 cold frames. One, I bought on Amazon. The other, I made out of an old window that my neighbor was throwing out set on top of some bags of peat and wood mulch that I plan to use next spring.  I just arranged the bags of mulch etc. in a rectangle, and set the window on top. Anywhere there were gaps, I covered the area with some small garbage bags filled with compost. It looks kind of trashy, but works.

Home-made cold frame

In mid-September, I planted the seeds for the following: spinach, chard, cilantro, lettuce, radishes, arugula, and carrot. I chose these
plants because they are known to be cold tolerant. (See the bottom of this post for a more complete list of cold-tolerant crops.)  I also put some of my rooted cuttings into the cold frame to protect them through the winter.

In November, I set up some PVC pipe hoop houses over the top of the cold frames.

To cover my home made cold frame I hammered some 2 foot long rebar into the ground.  I cut a 1" diameter PVC pipe into lengths of about 5 foot and arched them over the top of the home-made cold frame, securing the ends by inserting the rebar into the center of the PVC pipe.  I braced the two arches with a 3rd piece of stiff PVC pipe at the top of the arc. I secured the pieces together with zip ties. I then covered the hoop tunnel with 6mil plastic sheeting and

clamped it to the PVC pipe with plastic clamps found at the big box store. I anchored the plastic at the bottom with rocks and bricks.

To cover my store-bought cold frame, I cut a 1" diameter PVC pipe into four, 4 foot pieces, and one 5 foot piece. I connected them at the top with a 3-way PVC pipe connector. Unfortunately, one of the 3 holes for the connector contained a segment that was too small for the top piece of PVC pipe, so I connected that again with pieces of zip-tie. I secured the ends to the ground by inserting the rebar into the center of the PVC pipe. I covered this with 6mil plastic and secured it with plastic clamps from the big box store.  I anchored the plastic at the bottom with rocks and bricks.

(See, not so scientific. I didn't keep track of what type of seed, how much I planted, when it germinated or anything really.  My former biology professors would weep with disappointment. ;) ) 

RESULTS:

Several of my vegetables grew and I was able to harvest several winter salads. But, my method needs tweaking.

What Worked:

Spinach, chard, cilantro, lettuce, radishes, and arugula all grew.  The cuttings in their 4-inch pots seem well protected (these included sweet woodruff, rosemary, and gooseberries).  The radishes grew quickly and were harvested before the end of October. The lettuce also grew quickly until October, but then slowed down by December. Even so, I got 2-3 cuttings out of it, including one for Thanksgiving salad. The cilantro and spinach were the BEST. I can never get these two vegetables to grow without bolting in the summer. But in the winter under the cold frame (September - January) they have produced wonderfully and are sweeter tasting than usual! I cut the cilantro about 4 times, and the spinach about 3 times.

What Failed:

There was not quite enough plastic to cover the PVC tunnels.  When it got windy, the plastic would lift up along the bottom of the tunnels, despite the anchoring with rocks and bricks.

Some of the carrots germinated in the home-made cold frame, but did not continue growing past late October.  I think this is for two reasons:

1. I planted them too late. According to the chart in  Elliot Coleman's book, "The Winter Harvest Handbook", I should have started the carrots around early to mid August. Then, theoretically, they would have been ready for harvest around mid to late December.

2. I positioned the home-made cold frame facing East instead of South. I did this for easy access, but it may have decreased the amount of light getting to the carrots.


The arugula grew well in the store-bought cold frame through mid-November, but by mid-December they were frost burned and mushy.  I think this was because they were planted near the edge of the North-end of the cold frame, and thus got hit with frost.  This is somewhat surprising because it has been a rather mild winter for Michigan. We did get a couple of snows, but nothing outrageous. This has caused me to consider what might need tweaking...

DISCUSSION:

I am going to try growing winter carrots again, but next year I will start the seed in August. Hopefully I will have carrots for Christmas 2016.

I will be buying a larger piece of plastic to cover the hoops next year.  I want enough plastic left at the bottom that I can either bury some of it or anchor it more securely with bricks. I don't want the edges kicking up in the wind and releasing the built-up solar heat. 

I am going to use some left-over trex decking boards to build a proper cold frame for the window that I pilfered from the neighbor's trash.  Although the bags of peat insulate well, they look pretty ugly, and I don't plan on buying peat every year. If I have a trex frame I can move it around easily and store it away under the deck in the summer. I will post building instructions for this in the summer after I complete the construction.

 It seems to me that the store bought cold frame needs some insulation despite being double-covered with the plastic tunnel.  (The trex frame may need insulation as well.) This winter has been unusually  mild, with temperatures averaging around 40F - 50F. If we get a true Michigan winter (like the winter of 2013 or 2014), I think that more than just the arugula will suffer.

I am not sure how I will insulate the cold frame next year, but,I have several ideas:

1. I could dig a 1-2 foot deep square, plant the seeds at the bottom of the hole and put the cold frame over that.  My concern with this is that the edges of the hole might crumble and I will end up having to build yet another structure to hold them up.

2. I could fill several milk jugs with water, paint the outside black and line these up along the outer edge of the cold frame to act as heat sinks.  My concern with this that this will take up growing space inside the cold frame. I could line them up between the outside of the cold frame and the plastic hoop structure, but I think this might not hold heat as well.

3. I could pile leaves up between the cold frame and the plastic from the hoop over the top.  My concern with that is it may make a slimy mess on the surface of the cold frame by the time spring gets here.  I could decrease the mess by bagging the leaves in plastic garbage bags, but that is a waste of more plastic.

4. I could get some bubble wrap or styrofoam and line the inside of the cold frame with it. I could re-use that every year.  But would it be thick enough to do the job?

5. I could put some floating row cover over the plants inside the cold frame.  This might help, but I doubt will be enough by itself.  Perhaps if I insulated with styrofoam and applied floating row cover the plants would have enough protection.

If you are reading this and have any better ideas, or ideas that you've tried in the past, please let me know in the comments.  I would appreciate the help!

 I further plan to heat the cold frames next year from below: by building a hot bed.  Hot beds appear to be simple to set up (I have not built one myself yet - another upcoming experiment!) Apparently, you just dig a trench or hole, pack the bottom 12 inches of the hole with fresh horse manure mixed with straw or leaves, and then lay garden soil to a depth of about 5-6inches over the top of that. As the manure decomposes, it will produce a couple degrees of added heat.  I plan to build a hot bed in spring as well in order to assist the watermelon that I want to grow. I will post more about this when I do it.

I will, of course,  post again next winter to let you know what changes I made and how well the crops grew.  For now, I am pretty satisfied with my first attempt.  I got several winter salads and a ton of cilantro out of my little "experiment." I have great hope that I will only improve the process year by year.

BONUS! List of  38 Winter-Hardy Vegetables for Zone 5 Cold Frames:
(i.e. plants that will grow under the protection of an un-heated greenhouse or cold frame in Zone 5 Michigan, according to Eliot Coleman & others.)

If you live outside zone 5, Michigan, please see the chart in  Elliot Coleman's book, "The Winter Harvest Handbook to figure out what you might be able to plant in your zone. 

Arugula - in zone 5, plant between 8/1 and 9/1 to grow in cold frame over winter
Beets - in zone 5, plant between 8/1 and 10/1 to grow in cold frame over winter
Broccoli - in zone 5, plant between 8/1 and 9/1 to grow in cold frame over winter
Brussels sprouts - in zone 5, plant between 8/1 and 9/1 to grow in cold frame over winter
Cabbage - in zone 5, plant between 9/1 and 9/15 to grow in cold frame over winter
Carrot - in zone 5, plant between 8/1 and 9/1 to grow in cold frame over winter
Cauliflower - in zone 5, plant between 8/1 and 9/1 to grow in cold frame over winter
Celery - in zone 5, plant between 7/1 and 8/15 to grow in cold frame over winter
Celeriac - in zone 5, plant between 7/1 and 8/15 to grow in cold frame over winter
Chard/ Swiss Chard - in zone 5, plant between 6/1 and 9/15 to grow in cold frame over winter
Chicory - in zone 5, plant between 7/10 and 8/20 to grow in cold frame over winter
Chinese cabbage / Oriental vegetables - in zone 5, start seeds mid summer to grow in cold frame
Chives - in zone 5, plant between 8/1 and 10/15 to grow in cold frame over winter
Cilantro - in zone 5, start between 9/1 and 10/1 to grow in cold frame over winter
Claytonia - in zone 5, start between 10/1 and 11/1 to grow in cold frame over winter
Cress - in zone 5, start between 9/1 and 10/1 to grow in cold frame over winter
Dandelion - in zone 5, start between 9/1 and 10/15 to grow in cold frame over winter
Endive - in zone 5, start between 8/1 and 9/1 to grow in cold frame over winter
Escarole - in zone 5, start between 8/1 and 9/1 to grow in cold frame over winter
Kale - in zone 5, start between 8/1 and 9/15 to grow in cold frame over winter
Kohlrabi - in zone 5, start between 8/15 and 9/15 to grow in cold frame over winter
Leek - in zone 5, start between 8/1 and 8/15 to grow in cold frame over winter
Lettuce - in zone 5, start between 8/25 and 10/1 to grow in cold frame over winter
Mizuna - in zone 5, start between 8/15 and 11/1 to grow in cold frame over winter
Onion bulb -  in zone 5, start between 9/1 and 10/15 to grow in cold frame over winter
Onion greens - in zone 5, start between 8/1 and 10/15 to grow in cold frame over winter
Parsley - in zone 5, start between 9/1 and 11/15 to grow in cold frame over winter
Parsley root - in zone 5, start between 9/1 and 11/15 to grow in cold frame over winter
Parsnip - in zone 5, start between 8/1 and 9/1 to grow in cold frame over winter
Peas - in zone 5, start between 9/1 and 11/1 to grow in cold frame over winter
Potato - in zone 5, start between 7/25 and 8/20 to grow in cold frame over winter
Peppermint - in zone 5, any time before 9/15 to grow in cold frame over winter
Radish - in zone 5, start between 9/1 and 11/15 to grow in cold frame over winter
Rutabaga - in zone 5, start between 7/15 and 8/15 to grow in cold frame over winter
Sage - in zone 5, any time before 9/15 to grow in cold frame over winter
Sorrel -  in zone 5, start between 8/15 and 10/1 to grow in cold frame over winter
Spinach - in zone 5, start between 9/15 and 11/1 to grow in cold frame over winter
Turnip - in zone 5, start between 9/1 and 10/15 to grow in cold frame over winter

Note: Theoretically, you can also grow things like tomatoes, basil, peppers, cucumbers & melons year round. However, these would require a larger greenhouse due to their size as well as some coddling and extra protection to keep them warm enough.