Depending on where you are in North America, by now winter is either gently nudging or banging loudly on your door. Fear not: There are steps that can be taken to achieve good garden growth through the winter months. For readers wishing to increase capacity during the frosty months, read on.
With the cooler, wetter conditions late fall becomes slug season. In our downtown San Francisco garden, the slugs seem to first go for the broccolini. One way to dissuade them is by planting an “Onion Moat.” This perimeter is distasteful to slugs and snails and seems to slow down their slimy march into the leafy greens.
Another way to discourage pest is by spraying organic peppermint oil at dusk. I drop 10 drops into a 750 mL spray bottle. At dusk once per week, I spray the tops and bottoms of each leaf. This peppermint oil is unpleasant to slugs, while not leaving a foul taste in the produce. (Note: Only spray at dusk and not more than once per week.)
Another way to buffer root temperature is with mulching. One trick I like is to stack hay bales vertically on the windy side of the garden to create a windbreak. These bales can then, one at a time be laid out as mulch to insulate winter plants. As I mentioned in my previous post, Thinking Outside the Box, by building trellis’ to the north edge of growing areas, we increase vertical productivity. As an added bonus, each of these trellises also reduce the cold northern winds.
Another way to buffer plants and create a living mulch is to intensively plant. Known as the French Bio-Intensive Method, this method was brought to the United States by luminary Alan Chadwick through the University of California-Santa Cruz garden program and further popularized by Chadwick disciple, John Jeavons. In his book, How to Grow More Vegetables, Jeavons outlines how to intensively plant a patch for succession harvest.
By planting plants close together and radially harvesting single leaves each week with scissors, we can fit more plants into an area and create a contiguous canopy that shelters roots from the Sun and Wind. In this way we are mimicking a micro forest, where the falling of an old tree *(harvested veggie) makes a hole in the canopy for the next sprout to emerge. This takes advantage of solar gain in small spaces.
Green mulching protects the soil line from winter conditions, while producing a cover crop that will be able to be hand-tilled into the soil come spring. I like to use a mix of Fava beans, Clover and Snow Peas to give a multi story nitrogen fixing cover crop. This mass will buffer the soil from the cold and reduce erosion caused by harsh winter storms, all while fixing Nitrogen into the soil.
Want to fit more harvest into your winter garden? Start with “snatch crops.” These are quick-growing plants that can fit into the margins of your main crops. I like to utilize radish, turnips and beets, as well as lettuce and arugula for this purpose, as they will happily grow in the understory and edges of my main garden spaces.
This equates to bonus harvests! When one begins to get large enough to disturb the larger vegetable above *(such as broccoli, collards or kale), it is time to harvest the understory snatch crop and reseed again.
Greenhouse builders Penn and Cord Parmenter design thermal mass greenhouses that produce year-round tomatoes at 8,000-foot elevation in Colorado! How do they do it? The answer is in thermal mass. Thermal mass helps to slow the cooling of the soil temperatures at night by slow releasing trapped heat from the day.
To add thermal mass to protect more frost-sensitive plants, Cort and Penn have success by putting 1-gallon milk jugs full of water and basketball-sized boulders around plants. These options will both buffer night low temperatures and delay the day’s heat at night.
• Green Onion
• Collard Greens
• Sweet Peas
• Snow peas
• Fava Beans
• Try beets and garlic together
• Try parsley with carrots
Joshua Burman Thayer is a landscape designer and permaculture consultant with Native Sun Gardens. He is the Urban Agriculture Supervisor for Tenderloin Neighborhood Development Corporation in San Francisco, Calif. Find him at Native Sun Gardens and read his other MOTHER EARTH NEWS posts here.