What is the Arc of the Seasons?

The Arc of the Seasons in the secret to gardening success and making the most of your home garden. Vegetable and fruit crops are sensitive to temperature and changes in temperature so as a gardener you must be aware of how the seasons change. Unless you live at the equator or the arctic everyone has an arc to their year it starts at the coolest point and then gradually increases in temperature to the warmest point in the year. We don’t like to use months because depending on where you are December could be one of your coldest or warmest months and the seasons like spring, summer, fall, and winter are too general. Instead, we divide the seasons into cold, cool, warm, and hot. You can see on the diagram below how the seasons recur over and over in a repeating arc, hence the name Arc of the Seasons!

You can also see in the above diagram how we divide the seasons using temperature to distinguish between them. It is vital to know the difference between the cold season, cool season, warm season, and hot season plants to be a successful gardener. The cold season is the period in which your area experiences below freezing temperatures on average and there is a likely hood of frost or snow during this time. The cool season is when the temperatures start to increase so the average is above freezing, between 32°F (0°C) and 65°F (18°C), but there is still a chance of frost. The warm season is when all chances of frost have disappeared, and the average temperature is between 65°F (18°C) and 85°F (29°C). Finally, you reach the hot season in which temperatures are above 85°F (29°C) on average. After the hot season the temperatures will start to decrease again returning you to the warm season, then the cool season, and finally the cold season once more before the arc starts all over again. This is an example of the Arc of Seasons in a place that experiences the full range of temperatures and so depending on where you are you may not. The closer to the equator you live the fewer seasons you will experience because there is less temperature variation. An example of the Arc of the Seasons for us in Kentucky can be seen below. We do experience all 4 of the seasons to a degree and this is also an estimate based on past years averages not every year is the same. This year for example, here in Louisville, we moved from the cool season to the warm season very fast resulting in some plants that were planted late bolting.

Now that you have a grasp of how to determine the Arc of the Seasons where you are let’s discuss why it’s important! Different plants thrive in different seasons so to be successful and efficient in your garden it’s important to plant with the seasons and harvest with the seasons as well! You can plant at the beginning of each season and continually rotate out crops so that you can also have a rolling harvest. For example, kale, lettuce, spinach, and carrots are a few examples of a cool season plants that will bolt (go to flower and become bitter) as the weather gets hot so harvest it in the cool or warm season as it matures but make sure it is out of your garden by the hot season. Tomatoes on the other hand can be planted in the warm season when all fear of frost is gone and then harvested through the hot season and into the next warm season then pulled out by the next cool season. Then you can replace them with more leafy greens again! Squash is a great example of a plant that goes in in the warm season but can be harvested all the way through the hot season and into the cool season. Some plants like garlic can be planted in the cool season then live and grow underground through the cold season to be harvested in the next cool season. You can see how the rotation continues and if you can get the hang of the rhythms of nature and ride the arc of the seasons you can harvest nearly year-round no matter where you are! No matter what you do we want to encourage all gardeners to try things, at the end of the day all gardening is a bit of a risk, so go out and don't be afraid to make mistakes in your garden and learn from them!