When the first cool days of fall arrive, many of us are ready for a break from the summer heat. However, these cooler temperatures and shorter days signal the change in the seasons. Before we know it, we’re cleaning up the garden and dreaming of next spring.
If you’re not ready to say goodbye to spending time in your garden, you don’t have to call it quits until next year. Instead, you can extend your garden season by selecting frost-tolerant varieties, protecting crops with row cover and mulch, and adding protective structures will all help you grow later into the year.
Plant Frost-Tolerant Crops
When you’re planning your late fall and winter garden, pay careful attention to the types of plants you grow. While you may be able to get away with growing tender plants like basil and beans into the middle of fall, these plants won’t survive a frost. And they certainly won’t survive snow or temperatures in the 20s (-7°C)!
Fortunately, there are many crops that can tolerate frosty air and soil temperatures. Since these hardy crops include greens and root vegetables, you can still grow a diversity of plants when the weather chills.
Here are some frost-tolerant plants to try growing this fall:
These crops can not only tolerate low temperatures, but many will taste better because of them. That’s because the plants concentrate their sugars to help resist freezing. When you bite into a frost-sweetened carrot or collard, you’ll be amazed at how good the flavor is compared to an early-fall crop.
When it comes to ornamentals, consider hardy perennials that can survive chilly fall temperatures. Plants like red twig dogwood and winterberry provide colorful leaves and stems, and others like winter Jasmine and hellebore bloom during winter weather. You can also plant frost-tolerant annuals like flowering kale and violas.
Even if you plant crops that can handle cold, it’s important to think about how day length affects plant growth. After the summer solstice in June, days begin getting shorter and shorter. By the time October or November arrives, this decrease in day length leads to noticeably slower growth. Regions in the far northern hemisphere experience dramatic changes in this regard. Therefore, you should make sure to plant your seeds early enough if you hope to harvest during the late fall or winter.
If you’re not sure when to plant your seeds for fall, take note of your Persephone period. This refers to the time when the day length dips below ten hours. Once you know this data, you can count backward from this date to ensure your plants have enough time to mature before their growth slows.
Add Warmth With Floating Row Cover
Floating row covers are thin, lightweight layers of fabric designed to protect plants from extreme temperatures, wind, and insects. The covers let in light and water so your plants can receive the elements they need while they’re covered. However, removing the covers during warm periods will increase airflow, limit humidity, and decrease the odds that your plants will develop fungal diseases.
You can choose from multiple different types of row covers. These options vary in weight and, therefore, differ in cold protection and light penetration. When you’re choosing a row cover for frost protection, skip the heavyweight covers designed for insects. Although these covers can protect crops from light frosts, they won’t help mulch when temperatures drop below 30°F (-1°C).
Medium and heavyweight row covers are the best options if you want to protect your plants from frosts. You can also layer multiple covers on top of each other to protect plants from extremely frigid nights.
Although it may sound counterintuitive, you should avoid covering your plants with row cover before truly cold temperatures arrive. Exposing the plants to temperatures in the low 30s (-1°C) will help them develop a tolerance that benefits them later in the season. By the time temperatures in the low 20s arrive (-7°C), the plants will remain happy thanks to their built-in cold tolerance and protective covering.
You can drape the row cover directly over your plants, but morning dew and chilly temperatures can cause the covers to freeze to the plants. A better option is to use wire hoops to lift the row covers off the plants.
Add a Cold Frame
If you’re interested in adding a more permanent form of frost protection to your property, a cold frame is one good option. You can find many different cold frame configurations, but they all rely on glass or plastic to trap heat. The inside of the frame heats up during the day and warms the soil. When night arrives, some of the heat remains.
Setting your cold frame next to a south-facing brick or stone wall can provide extra protection from frost. The wall will heat up during the day and release some of the heat after the sun goes down. You should avoid placing a cold frame next to north-facing walls since these will limit the amount of light that reaches the frame.
When you’re using a cold frame, make sure to close the frame a few hours before the sun goes down. If you wait until it’s dark out, you won’t be trapping any heat! However, you should also be aware that the frames can quickly heat up to temperatures that are higher than you may expect. Therefore, keep an eye on them during sunny days and vent or open the frames if necessary.
You should also pay attention to the humidity inside your frame. Moisture can quickly build and increase risks of fungal diseases like powdery mildew and anthracnose. Keeping the soil on the dry side and venting the frame can decrease humidity and limit the chances of disease.
Invest in a High Tunnel or Low Tunnel
If you’re serious about winter growing, a high tunnel can open up all kinds of new possibilities. These structures trap heat similar to a cold frame, but their larger size makes them easy to navigate while standing up. You can find high tunnels that are as small as five by ten feet, as well as those up to 100 feet long.
Since high tunnels are so large, they allow for better airflow than a cold frame or low tunnel. Opening the doors and sides allows air to move into and through the tunnel, and installing fans keeps air moving even when the tunnel is closed.
Despite their large size, high tunnels still trap plenty of heat and allow you to grow later into the season. Like most covered structures, they heat up more quickly on sunny days than cloudy days. If you need an extra layer of frost protection, you can cover the crops inside your tunnel with a layer of row cover.
If you don’t have the space for a high tunnel, you can utilize low tunnels. These smaller structures stand only a few feet tall and a few feet wide, making them able to fit into backyards and small gardens. You can make low tunnels from metal or PVC bows and customize them to the size you’d like.
After the tunnels are up, you cover them with a sheet of UV-resistant plastic and secure the sides to the ground. This plastic traps heat from the sun and protects crops from frost. Like with cold frames, low tunnels can quickly become hot, so make sure to vent the sides on warm and sunny days.
Mulch Your Crops
When you’re growing crops in cooler weather, you may think about the air temperature. But the soil temperature is also important. Not only does warm soil help protect the plant’s roots, but since the soil holds heat better than the air, it can help roots remain warm when air temperatures drop.
One way to keep the soil warm is to mulch the soil around your crops. The mulch will act as an insulator against chilled air. You can use many different materials as mulch, including straw, wood chips, and compost. All of these materials will act as insulators, but darker mulches will trap more heat than lighter ones.
