Red cabbage in snow
It was 30 degrees Fahrenheit last night in my Zone 6b garden and I harvested cauliflower and broccoli this morning. It’s early November and the cold-hardy brassicas and greens are still growing and maturing in anticipation of winter harvest.
As a very lazy gardener I don’t employ any cover on my winter garden other than a little straw tucked around plants. Yet we manage to keep an excellent crop growing 10 months out of every year, including an extremely varied winter harvest. Here’s how you can too by using ice-bred and cold-hardy varieties.
What are Ice-Bred Vegetables?
Ice-breeding is the process of growing stable, open-pollinated plants, in very cold conditions and selecting seed from those with the most resistance to the cold. The term was coined by Brett Grohsgal of Even’ Star Organic Farm in Eastern Shore, Maryland. He often starts by crossing different varieties to generate greater genetic diversity.
To increase cold hardiness he grows out many plants and reselects the ones which survive the most extreme cold. His Ice-Bred Arugula, Rapa, and Smooth Leaf Kale varieties have been introduced into the seed market through Fedco Seed and are available there and through other seed houses.
Can Anyone Produce Ice-Bred Plants?
Of course! To ensure your success start with one of the Brett’s varieties or a cold hardy variety from a seed house like Johnny’s Select Seeds that specifically grows out plants in cold conditions. Make sure to choose their open-pollinated (not F1 hybrids) varieties so you can save seed from your plants.
Grow these plants in your garden for seed-setting at the colder end of their temperature tolerance. Southern Exposure, a Virginia grower and seed source, has a great winter gardening guide listing cold tolerance for types of vegetables along with specific varieties that are hardy at extreme temperatures.
- Save seeds from your hardiest plants keeping track of the lowest temperatures they survived.
- Plant those seeds in your garden next year for late-year seed collection. Plant as many as you can for better diversity.
- Save seeds again from the hardiest plants, again noting temperature extreme.
After only a couple of years, you now have an improved variety that performs specifically well in your winter garden.
These plants will withstand your cold winters, laugh at frigid temperatures, and provide you with food throughout the months when most gardens only sleep. Even when they go dormant these plants will often perk up and start growing rapidly at the first sign of early spring warmth.
Winter time Swiss chard
Harvest Vegetables March through January
Using proven cold hardy varieties, including specifically ice-bred vegetables, we consistently harvest ten-eleven months out of each year without benefit of cover. Other than improving cold tolerance in open pollinated (OP) varieties, purchasing cold hardy hybrids (F1) ensures our success. Here are some of the varieties that give us consistent results in Virginia’s winters.
Tolerant to 30˚F
- Song Cauliflower (F1)
- Purple of Sicily Cauliflower (OP)
Tolerant to 25˚ F
- Arcadia Broccoli (F1)
- Napa Cabbage – Rubicon (F1)
- Winter Density Lettuce (OP)
- Rouge D’Hiver Lettuce (OP)
- Merlot Lettuce (OP)
- Marvel of Four Seasons Lettuce (OP)
- Bouquet Dill (OP)
Tolerant to 20 Degrees F
- Chinese Red Meat Radish (OP)
- Shawo Fruit Radish (OP)
- Rainbow Swiss Chard (OP)
- Brunswick Cabbage (OP)
- Deadon Cabbage (F1)
- Ruby Perfection Cabbage (F1)
- Chioggia Beets (OP)
- Beas Kohlrabi (F1)
- Boule D’or Turnip (OP)
Tolerant to 10-15˚ F
- Scarlet Kale (OP)
- White Russian Kale (OP)
- Cilantro (OP)
- Bloomsdale Long Standing Spinach (OP)
- Mache (OP)
Overwinter Crops for Early Spring Harvest
Mature lettuces die around 25 degrees, but 4-6 inch seedlings do well down to 10 degrees. We plant our last lettuce beds each year mid-October in order to achieve a March harvest. Rapini is another excellent vegetable to overwinter for an early spring harvest. Plant it in the fall and then mulch over with straw for the winter.
Are You Ready to Expand Your Gardening Year?
You too can grow your food for many more months than conventional gardening wisdom would lead you to believe. You can do it without the work of maintaining a green house or hoop house, without the tedium of keeping row covers from blowing away, and without raising and lowering cold frames lids.
The majority of the work you’ll need to do to achieve a longer gardening year involves curling up with a hot cup of tea and a pile of seed catalogs. Then spend your month(s) without harvest planning out your garden beds for the new season of growth.
Let me know how your garden grows next year!
Sheryl Campbell is an heirloom gardener, shepherd, and edible flower educator who owns Bouquet Banquet in Virginia’s Shenandoah Valley. Read Sheryl’s previous blogging with Mother Earth Gardener and Grit and read all of her MOTHER EARTH NEWS posts here
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