One of the things that can cause the most damage to plants is frost, but that doesn’t mean there’s nothing you can do about it. There are many things you can do to keep your plants safe all winter long.
Let’s take a closer look at why frost is so dangerous and what actions you can take to help your plants survive the winter.
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How Does Frost Affect Plants?
Frost affects plants in two ways. One is direct and one is indirect.
Frost causes direct damage to plants by freezing the plant tissue itself, which leads to the cells rupturing. The leaves will get wet and damp, and you may even see ice crystals inside them.
Frost also freezes the ground around the plants, which means that it interferes with the water and nutrient supply getting to the plants.
The extent of the damage usually depends on how cold the temperature gets. Temperatures of under 29 degrees (-1.7°C) are typically the most damaging, though this does vary from plant to plant, as we’ll see later.
Another factor that determines the extent of the damage is how long the plants are exposed to the colder temperatures.
For example, if the temperature drops below the safe range for a half hour or so, the plant won’t experience as much damage as it would being exposed to unsafe temperatures for several hours.
When to Protect Plants from Frost?
The best way to protect plants from frost damage is to pay close attention to your local weather forecast. Most new stations and apps will give you a frost warning, alerting you that it’s time to take action.
That said, you shouldn’t rely on these forecasts entirely. Everyone knows that weather forecasts are not completely accurate, so it can be helpful to figure out things to look for to clue you in that it might frost.
One thing you can look for is cloud cover. Overnight temperatures tend to get lower when the sky is clear because there are no clouds to keep in any of the warm air.
That said, when it gets later in the year and you know that frost is coming soon, start preparing. It never hurts to be ready so you can act quickly when you need to.
What Temperature Causes Frost Damage to Plants?
Every plant is different. Some are hardier than others and are able to survive just fine if the temperatures get below freezing. To properly protect your plants, you need to know what temperatures are critical for causing frost damage to them.
10 Easy Ways to Protect Plants from Frost
Here are 10 things you can do to help your plants stay protected from frost:
1. Choose the right plants
As you can see from the chart above, some vegetables are much harder than others. This means that they can tolerate colder temperatures and other harsh conditions and bounce back pretty easily.
Other vegetables are much more sensitive and might be affected by temperatures that aren’t even below freezing.
If you live in a climate where it frosts early and frequently, it’s helpful to choose plants that are a little more resistant to frost damage. These include marigolds, broccoli. cabbage, spinach, leeks, and Swiss chard.
On the other hand, you should avoid plants that are sensitive to frost. These plants include begonias, impatiens, citrus trees, avocados, and peppers.
Think carefully about the plants you are choosing. When you choose the right ones, it’s easier to give them the protection they need.
2. Be smart about plant placement
Try to place plants in areas that are resistant to frost. Keep plants close together and place them along walls and benches to protect them from frost damage. This is particularly effective if the walls or benches are dark in color. They will absorb heat during the day and keep the plants warmer overnight.
Location is very important. Elevated positions are better than low-lying areas, especially for younger plants. Cold air sinks, which means that the coldest air settles in low-lying areas.
3. Consider the temperature at ground level
Just because the forecast is predicting a certain temperature or your outdoor thermometer is telling you it’s above freezing doesn’t mean that your entire yard is that temperature.
Make sure you check for cold air pockets. As we said, cold air sinks, so the coldest areas of your yard are likely to be those places where there are depressions in the ground. Avoid placing plants in these spots.
If you don’t have a choice or if you’re looking for a way to add some warmth to the ground, add some mulch or landscaping fabric. Either of these will help keep heat in the ground, keeping the roots warm and warding off some damage.
4. Acclimate seedlings
One way to help new plants survive cold weather and frost is a process called hardening. Acclimate seedlings to the outdoors by slowly exposing them to the cold. Start about two weeks before you plan to transport them into the ground.
When the weather’s about 45 degrees F (7°C), put them outside in a cool, shady spot. Then, bring them in at night. After two weeks of this, the plants should be able to tolerate the cold a little more.
5. Cover plants at night
Most of the time, hard frosts happen overnight, so make sure you prepare your plants before dusk.
Make sure the cover covers the entire plant down to the soil. The point of covering the plant is to hold in as much heat as possible, and leaving areas open at the bottom will only let cold air in.
Use stakes to keep the material in place, but make sure it doesn’t touch the foliage or trunk. Leave some space around the trunk, too. This makes sure you get as much heat as possible coming up from the soil.
There are a lot of things you can use to cover plants, including drop cloths, empty milk jugs, blankets, and sheets. Remember, these covers don’t have to be too elaborate or expensive. They don’t even have to look pretty. They just have to get the job done.
In the morning when the temperature rises, remove the cover so your plants get the benefit of the bright sunlight.
6. For something more durable, try a cloche
Cloches are glass jars with wide bases that you can place over plants. Most are designed to fit over single plants, but you can find some that are large enough to cover entire rows. Place them as you would any other cover, and remove them in the morning.
You certainly don’t need to invest in cloches, but they are some of the easiest tools for covering plants. All you have to do is put them on and take them off, there’s no need for any structure to keep them from touching the leaves.
Plus, cloches are made of glass, so they’re highly decorative. You can easily use them for other purposes during the warmer months when frost isn’t an issue.
7. Make sure you water your plants before the frost
If you water the plants before the frost, the soil will release the water after you cover the plants for the night. This will increase the humidity underneath the cover, helping to raise the temperature and prevent the leaves from frosting.
8. Use water jugs as overnight heaters
During the day, fill up some water jugs and place them outside during the day, letting them warm in the sunlight. Before you cover your plants at night, place the water jugs around them to keep things a little warmer under the cover.
9. Don’t leave potted plants outside unless you have to
If you have potted plants, there is no reason to leave them outside, unless they’re too heavy to carry. Why risk exposing them to frost if you don’t have to?
Hanging baskets should also be brought inside. The roots of plants in hanging baskets are even more exposed than plants in the ground because they do not have the benefit of the warm ground around them.
If you can’t bring hanging baskets inside, move them closer to the ground and cover them as you would any other outdoor plant.
10. Wrap trees when necessary
Not all fruit trees need to be wrapped, but you should pay special attention to fruit trees. Most fruit trees have bark that is very sensitive and can split and crack. Wrapping these trees can help prevent this damage.
Use multiple layers but keep the covering somewhat loose. Leaving a little bit of air between the wrapping and the trunk helps make the insulation more effective because it holds warm air in the space, close to the tree.
What to Do After a Frost Hits Your Garden?
The first thing you have to do after your garden has experienced is damage control. Check your plants carefully and identify any damage. When plants freeze, the tissues inside the plant are severely damaged.
Are these plants dead? Not necessarily. You may be able to contain the damage and save part of the plant. But, believe it or not, it’s better not to do anything right away.
As hard as this is, the best thing you can do is wait and continue to do everything you can to protect the plant. Don’t start cutting and pruning right away or removing plants at the roots.
Cutting back the dead parts of the plant may only end up exposing the part of the plant that is still living to the harsh weather. Pruning also stimulated growth, which is not what you want to do in the winter season.
When the weather is warm and frost is no longer an issue, take time to assess the damage. Prune dead parts of the plant away and pull out whatever didn’t make it. This will stimulate more growth at the proper time of year.
Frost can cause significant damage to the plants in your yard or garden, but don’t worry. There are many things you can do to prevent frost damage in the first place.
To recap, the best way to treat frost damage is to prevent it from happening in the first place. The easiest way to do this is to choose plants that are suitable for your climate. Acclimate seedlings, and use mulch or fabric to cover the ground, particularly in low-lying areas that are most at risk for frost.
Cover your plants before the first frost, and remove the coverings in the morning when the temperature rises and the frost is gone. Water your plants before covering, and consider placing hot water bottles under the covers to act as heaters overnight.
Sometimes, no matter what you do, frost damage will still occur. In this case, don’t jump in and start pruning right away. The best approach is to leave the plant alone and wait and see what happens when the weather warms up again.