Winter can be a challenging time for us gardeners and homesteaders. Cabin fever sets in and you itch to get back into the garden. While a season of rest and relaxation can be nice, there is actually a way to grow a garden in the winter. There are two key factors to keep in mind when winter gardening–temperature and sunlight.
Why won’t plants grow?
While cold temperatures do slow growth, the biggest factor in growing a winter garden is sunlight hours. Most plants need at least 10 hours of sunlight a day for growth to be stimulated. Direct sowing or transplants–little to no growth will occur during the darkest days of winter.
Here in zone 8A, we begin to dip below 10 hours of sunlight on December 2nd and do not rise above 10 hours until January 10th. The amount of daylight you receive on a given day is unique to your location and you can find out when you dip below 10 hours and for how long online at sunrise-sunset.org.
Note: This post may contain affiliate links. We earn a small commission at no additional cost to you. Read our disclaimer for more details.
Two Winter Growing Seasons
Winter gardening has two general phases in zones 7B-8B – plantings at least 4 weeks prior to the winter solstice or 4 weeks after the winter solstice. The reason for this? You guessed it, the lack of sunlight. Crops planted between this period of time grow very lethargically (if at all).
But when crops are planted at least 4 weeks prior or after the winter solstice, there is enough sunlight for good consistent growth. This gives those crops a fighting chance against the weeds, which otherwise always seem to get the advantage over the crops we plant!
There are two categories of crops to plant prior to the winter solstice–crops that will mature and hold well in the garden and those that will overwinter and be ready to harvest in the late winter. In the first group the goal is to have your crops fully mature so that you can harvest to eat them without relying on regrowth. Cold-hardy crops in this category include radishes, kale, spinach, lettuce, etc. In the other group are slow-growing crops that will go dormant during the darker days, but will start growing again as soon as the days lengthen. This category would include crops like onions, broccoli, and cauliflower.
Are you sure daylight is that important?
At the farm I work at, we have experimented with direct sowing crops the week after Christmas versus waiting until the day length increased. We planted winter-hardy crops such as arugula, radishes, beets, lettuce, mizuna, and claytonia and discovered that delaying planting until 10 hours or more daylight results in healthier and faster growing plants. This was fascinating to analyze as it was so consistent over so many different types of crops!
How to help winter garden plants?
There are additional things that we can do to help aid plant growth when winter gardening. The first is to insulate the soil. Root growth is greatly influenced by soil temperature so the warmer we can keep the soil the more root growth can occur. This can be achieved with shredded leaves, black landscaping fabric or growing in a cloche or greenhouse.
Warming the air mass around the plants can also be beneficial, especially to keep the frost off your tender greens. We have found frost blankets called Agribon to be especially useful for this purpose. One of the keys to success with such blankets is to keep them off the plants. If the frost blanket freezes while touching your plants, it will burn them just as bad as if they had frost. I like to use 9-gauge wire (sometimes labeled as high-tensile wire). It can be found easily at most garden stores, TSC, or Tractor Supply. By cutting the wire in 48 inch long pieces for a 30” wide bed, it creates a perfect semi-circle to carry the frost blanket above the plants.
What else can we do?
Bolstering the photosynthetic ability of the crops is also very helpful during this season and can be done easily by using a foliar fertilizer such as fish emulsion. We have had great success doing this once per week in the winter and bi-weekly in the summer. The results are not seen immediately, but we have noticed in particular that the plants fertilized via their leaves have thicker healthier leaves and stalks compared to plants with no foliar fertilizer. You can find more about using fish emulsion here.
Take a deep breath
Even though winter gardening can bring joy and fresh veggies in the cold dark of winter…it also does a great job of testing our fortitude! The seedlings do not take off like spring seedlings. The weather is never predictable and neither are the reactions plants have to the different weather patterns. In our region of South Carolina, we can experience 15-degree temperatures and wind one day followed by sunshine and 60s the next. Despite the challenges, there is nothing quite like a winter salad or the sweetness of a carrot harvested after a hard frost make it all worth it!
We hope your winter gardening adventures show you the incredible hardiness of plants, their ability to adapt to changing environmental conditions, and the mesmerizing magic of plants turning sunlight into delicious food.