What does the arrival of 10 hour days mean for your garden?

In early November we have the arrival of 10-hour days in our garden.  Short days have a big effect on how things grow in your garden.

What does the arrival of 10-hour days mean for your garden?

Mid-November means the arrival of days with less than 10 hours of daylight. One of my favorite gardening authors Elliot Coleman refers to this time of year as the Persephone months. This has a reference to the story of the Greek goddess Persephone who according to the myths spends the winter months with her husband Hades. During the time that she is gone, her mother, Demeter, mourns and neglects her duties as the goddess of the harvest. This according to the ancient Greeks is why we have winter! (For a little more detailed account of this story click here).

It turns out that instead of a missing Greek goddess, the real cause for winter and the lack of growth in our gardens is the missing sunlight!! The arrival of 10-hour days basically shuts down growth in your garden.

Why does your Garden need Sun?

Nearly all garden crops simply shut down when there are less than 10 hours of daylight per day. Plant growth becomes almost (but not quite) zero during these dark months. Even leafy greens like lettuce, spinach, and Swiss chard hardly grow at all during this time.

The arrival of 10-hour days in your garden varies based on your latitude. The further north you live the sooner those days arrive and the longer they last. An easy guide for most people in the north is to assume the Persephone months are basically November, December, and January. My area is a good example of this. We live at roughly 41 degrees north. 10-hour days arrive for us right around November 10th and stay until the end of January.
Of course, for a big portion of the northern hemisphere, the lack of daylight corresponds with cold winter weather. But believe it or not, it’s not the cold weather that shuts down our gardens. Even plants that are protected by greenhouses, cold frames, or hoop houses still stop growing during the winter. So even those of you in the much warmer southern climates will find your vegetables going to sleep when the 10-hour day arrives.

So how do we deal with these winter months and still have veggies to harvest?

The key of course is to have all of your veggies mature BEFORE you have less than 10 hours of light. It also means that you need to plan on growing plants that require less light for successful production. If you are growing a plant to eat its fruit or root then you must have 14 or more hours of light to get decent production. So instead during this time of year, your growing efforts will need to be focused on plants that you grow for their leaves.

Vegetables to Plant in Fall for Winter Harvest

There are over 20 different crops that you can grow in the fall and then harvest during the winter. The list includes lettuce, spinach, Swiss chard, arugula, mache, beet & turnip greens, kale, mustards, Asian greens & cabbages, and many more exotic greens.

Carrots and parsnips if planted early in the fall also make fantastic winter crops.

All of these crops will grow a little during this low light period, but the growth rate will be very slow!  So if you have plants that do not make it to maturity before the 10-hour days arrive, consider letting those plants overwinter in a cold frame. When the longer days arrive in February the plants will take off and give you a very early spring harvest.

Of course, you will also need to protect your plants from the cold winter temperatures. This is where having a few cold frames or hoop houses comes in handy. Those of you who live in an area where the winter is especially mild may even be able to protect your crops using a piece of heavy fabric row cover.

The arrival of days with less than 10 hours of daylight will be happening for most of us in the northern hemisphere within the next week or two. But the lack of sunlight doesn’t have to spell the end of our gardens. Why not learn now how to extend your garden harvest next winter?

Below you will find a list of resources and posts to help you learn more about year-round gardening:

Year Round Gardening Video Course
Winter Gardening Structures
Winter Gardening Series
Building a Garden Cold Frame
Protecting your Garden from early frost