The onset of fall brings seasonal joys like apple picking, fresh-baked pumpkin pies and picturesque foliage. If you’re a gardener, however, the dipping temperatures are a reminder of pesky frost that can creep in, quickly infiltrate your growing space and spoil months or weeks of hard work that you’ve spent out in the soil.
When frost hits crops, the formation of ice crystals in plant cells stops the movement of essential fluids to tissue, according to master gardeners at the University of California’s Agriculture and Natural Resources. Those crystals can also slice open cell walls and cause further damage to tissue. If your garden has fallen victim to frost, you likely remember the sad sight of wilted, water-soaked leaves that have turned dark brown.
While cool season vegetables, like garlic, broccoli and cauliflower can withstand colder spells, crop experts caution that any temperature below 33°F will damage warm season vegetables. This includes crops like peppers, tomatoes, cucumbers, and melons.
Luckily, there are a few ways to protect your plants from the perils of frost. We’ve assembled this guide that will take you through a number of options that can help ensure your garden survives when the weather gets colder.
1- Hoop Houses
Hoop houses are a wise choice for those who want to stretch their growing season into colder temperatures. These contraptions consist of hoops, arched pipes, wires or frames bent over your garden and covered with a thick layer of greenhouse plastic wrap. They provide a controlled, insulated environment for your garden. You can buy hoop house kits at garden centers or online. We also have a Modern Farmer DIY guide that will show you how to make your own on your own.
It may seem counterintuitive, but water can also act as an insulator. When plants are well watered and the soil is moist, heat is emitted upwards. Water your plants before the temperatures drop at night, but don’t drench them. As a general rule, the earlier in the day you water your garden when the sun is out, the more water you can give your plants as it will have time to absorb into the soil.
If you’ve caught sight of some frost before the sun comes up, you can also lightly water your plants that morning. This helps the plants acclimatize to the temperature change as the sun comes up. If the sun comes up and the plant still has frost on it, its cells often aren’t able to adjust quickly enough, which causes them to rupture. A light coating of water has the ability to release some heat in a more gradual way.
3- DIY Protective Blanket
For severe frost that is six to eight degrees below freezing, the best option is to purchase a heavier fabric grow cover at a nursery that is specifically for frost protection. But if you don’t have access to one, you can easily make frost covers from a variety of materials from bed sheets, blankets or painter’s plastic if there’s a warning for a light frost.
Throw your covering of choice on your crops in the evening and use clips or clothespins to secure it over your tomato cages or heavier vines. Alternatively, you can weigh down the perimeter with a heavier object like bricks or rocks that will ensure there’s a secure barrier from the frost and your cover doesn’t blow away if confronted by wind. If you are working with delicate crops and you’re worried about the material weighing them down, you can hammer some metal garden stakes into the ground to prop up your cover.
Ensure that when the sun rises in the morning, you remove the cover so that your plants can breathe.
4- The Cloche Technique
The cloche method is another way to cover your plants. It involves placing a lantern or bell shaped container, either made of glass or plastic, over each plant to provide them with some barrier and insulation to frost. Depending on the size of your plant, you can use items like milk or soda jugs with the bottoms cut out. You can also try buckets or glass mason jars. It’s important to note that this method can trap heat quite effectively, so if it’s a hot day and you don’t have an option for ventilation, like taking the top caps off the cloche containers, wait to cover them until late afternoon or early evening and monitor the temperature.
5- Take them inside
If you have the space and you’re weary about leaving your veggies outdoors, another option is to transplant them into a pot that can be taken into your home or a greenhouse. Do this using a shovel and a large pot. When digging your plant up, it’s best to retain as much of the root mass as possible. To do this, ensure that as you slice your shovel down around the plant to carve a block of soil that you will uproot that you’re leaving ample space (a few inches). As you place it into a pot, add more soil accordingly so your food babies have a cozy new home.
Mulching, which involves spreading a thin layer of material on your garden topsoil, offers many perks like smothering weeds, adding nutrients and reducing run-off. It can also insulate the soil, plant roots and all the living things that promote a healthy growing environment. This is particularly useful during temperature fluctuations, such as when frost hits in the morning or at night. There are a lot of different ways to create your own mulch. But right now you can take advantage of the abundance of leaves falling off the trees onto the ground as a practical option.