Temperature Control for Winter Storage Crops

Courtesy of Wally S., Wally’s Urban Market Garden, Saskatoon SK

More and more consumers go to year round farmers markets so they can know where their food comes from, even in winter. What they find at my stand are storage crops, like beets, carrots and potatoes.

Part of the challenge of year round marketing of produce in cold weather winters is keeping your storage vegetables in good physical condition for several months. Just as in the summer, I take SPIN’s high road by using a cooler. Keeping it at the right storage temperature is key. My cooler is on average around 35 F, or few degrees above freezing celsius. It’s in my garage, along with a work area for prepping produce. I keep it in my garage, which is heated with a small plug in radiant space heater. The thermostat is set to 50 F.

A few nights ago it was -35 Celsius overnight. Just made a celsius to fahrenheit calculation and ironically this is the temperature where the two scales converge: -35 C is the same as -35 F. So I have to deal with the outdoor temperature, the garage temperature and cooler temperature. The heater keeps the garage at 50 F., but the question is how do I keep the cooler at the desired temperature? I find just partially opening the cooler door allows air to seep in from the garage, when it is very cold outside. When temperatures outside get warmer, I can shut off the heater for certain periods of time and close the door for the cooler. Right now the cooler temperature is 34 F, which is about optimal. The aim is to keep it above freezing, and below 40 F.

SF photo Wally temp2


This is not a high tech method for sure, but it works, as long as I keep an eye on things happening inside and outside. So you don’t need an elaborate setup to keep your farm stand stocked with the staples that keep your customers coming, and your cash flowing,  when the snow is flying.


Winter Markets Keep the Cash Flowing

Courtesy of Wally S., Wally’s Urban Market Garden, Saskatoon SK

My operation in zone 3 Canada has been a year round one for many years. Now I’m starting to hear from other SPIN farmers who are usually trading their tillers for a snow blowers about now, that winter markets are booming, and that they, too, plan to keep production going.

For instance, a nursery owner in Minnesota is setting up a room to do 36 10×20 trays indoors under lights, and is planning to provide microgreens to his customers from November to May. He wants to know what kind of yield to project from each 10 x 20 tray, and the pricing he should set.  Here’s what I suggest:

  •  Try doing about 10 trays per week for starters.
  •  Think about adding micro radish to the peas for a salad mix. Very popular. Can also sell them as stand alone greens.
  •  I get about 1/2 lb. of micro radish per tray. About 1 lb. of pea greens.
  •  Stay with SPIN’s mix and match pricing of $3.00 2/$5.00, and unitize accordingly, with the idea of targeting at least $20 of revenue per tray. [Note that in some markets SPIN farmers are reporting they have been able to push SPIN’s pricing benchmark to $4 or 2/$8].  
  •  To see if you can save on costs, try growing without lights initially, just room light.
  •  Add lights, say to a max of 8 hours per day, and observe what it does for your production, and determine whether you need them.
  • Some commercial growers grow pea greens/micros in darkness, to get a yellow looking product, which chefs like.

DDG5 photo 45 DSC00574

There are many ways SPIN farmers can continue to make hay while the snow flies. Here are the SPIN guides that can give you some more ideas on how to keep your cash flow going during the winter months:  Indoor Farming with MicroGreens  Four Season Marketing


Edible Houseplants are a Good Indoor Crop

Courtesy of Wally S., Wally’s Urban Market Garden, Saskatoon, SK

I am in hard winter here right now, so the only outside work I have is shoveling snow. Believe me, there is no market for that here in Saskatoon. Given that we go to three markets a week, year round, we are having to concoct money making ideas. One new product we have test marketed the last couple of weeks is edible house plants, specifically garlic. We sell them in the containers you see below for $5.00 each.

SPIN photo farm stand display

We plant 5 cloves per container. Three weeks later you have a marketable product. We use indoor grow table/racks for this production. Plants are sold with the idea that you harvest the green garlic, and it will regrow to be harvestable again. Given the low price point, people are willing to give it a try, and they are moving well.
Wally, Zone 3

Indoor Grow Tables Inexpensive Setup for Winter Production

Courtesy of Wally S., Wally’s Urban Market Garden, Saskatoon, SK

You don’t need an expensive greenhouse to keep going through the winter. I use  grow tables in my basement. Advantage: you don’t need to pay to heat it. There is a small cost for lighting, but it’s a fraction of what you can make from this type of setup. I can fit 16 trays per table.

This week Gail and I are ramping up indoor winter greens production. A chef’s event coming up means I have to deal with 30 trays of micro greens. We will lay them out on the table and shelves, and cut before Nov. 8. We’ll be doing a winter salad mix, which will be pea greens and a variety of micro greens. Pea greens might seem a little foreign to many people, but when you make them a part of a salad mix, then it is an easy sell. Micro greens are a luxury item at winter markets, and you can charge luxury prices.

SPIN photo grow table in basement 2

Winter Growing of Micro Greens

Courtesy of Brenda S., Thompson Street Farm, Glastonbury CT

For winter sales of micro greens, I’m doing about 20 trays a week to start. I have a winter market through December 22nd,so I will see how demand is. If I can control the temperature in the greenhouse I will do more. Yesterday I started 5 trays on heat mats in the greenhouse. The rest of my trays are in a back room in my house on racks. If the trays in the greenhouse survive the overnight lows, I will start more using some kind of alternative heat source. I’m focusing on heating the trays instead of heating the air.

For mats I’ve purchased reptile heat pads/mats. I’m turning on the mats when the sun goes down. The greenhouse is warm enough during the day, and they don’t need additional heat. The product I’m using is Zoo Med ReptiTherm Under Tank Heater. Amazon.com is selling them for $13.71 for a small mat. I’m also using a large seedling mat as well. I realize if I’m going to do a lot of trays this wont be practical.

Another cheap idea I’m toying with for protecting the greens overnight is putting the trays on an electric blanket.

In addition to growing micro greens on shelves in the greenhouse, I will also be growing arugula, lettuce and green onions in the greenhouse beds. I also have several of my outdoor raised beds growing arugula and lettuce. My leased SPIN field has turnips, carrots and tatsoi, all unprotected at this time.

Turnips and tatsoi I harvest every week. The carrots are just coming up now. A local farmer suggested I just leave them there for winter and see what happens. Long story as to why I’m growing carrots this winter. Short version – I hired a high school kid to help me plant a 1/4 acre. Yup – he seeded an entire segment with carrots instead of arugula.

Micro Green Menu:
sunflowers (indoors)
popcorn shoots (indoors)
pea shoots (indoors)
purple radish
chia (indoors)

DIY Heat Mat

Courtesy of Richard E. MT

When it comes time to sprout seeds, it is warm enough that I don’t need my electric blanket so I use it for seeds. I fold it to fit the space needed and cover with plastic or tarp. I do it in my basement and turn off the blanket when seeds are sprouted, after about 7-10 days. Ambient temp is about 55 degrees.

I put up shelves out of scrap lumber using screws so it is easy to disassemble and store. The bottom of each shelf supports a light on a small chain to make it easy to adjust for the shelf under it. The secret is bright light so you don’t get spindly plants. I start about 1,152 plants, mostly tomatoes and peppers, this way and it has worked well for us. The cool ambient temp makes hardening of the plants easy as you put them outside.

Heat Mat A Good Investment

Courtesy of SPIN farmer Mike B, Iowa:

I don’t think you can go wrong with a good heat mat. You are paying for the ability to be able to control the temp. to within a few degrees, as well as for the amount of space you want to heat for seedlings. I’m growing on about 1.5 acres and have a heat mat that
is 24″x 48″,  and it was a great investment. I went for the slightly larger size ($150.00) knowing that I could always grow into it.

Winter Growing Mache in OR

Courtesy of Josh V., Portland OR
The one green I’ve had consistent good luck with, uncovered, through the entire winter, is mache.  This is not a productive plant, but it is very tasty and if you let it go to seed it will establish itself as a winter “weed,” and it’s a welcome one in my plot.