You’re well aware of freezing weather, but do you know what is considered a hard freeze and how lethal it is to your garden? Most states get first, and last frost dates, and gardeners stick to them. They’re important when planting new plants or transferring the old ones.
The hard freeze happens during winter, and there’s just so much you can do to help your plants survive. Unfortunately, sometimes it can even cause damage to your home!
What Is A Hard Freeze?
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There are 3 stages of winter temperatures: frost, freeze, and hard freeze. Mind that these terms are used from an agricultural point of view, not meteorological. All stages affect the 4 P’s – people, pets, plants, and pipes.
As night temperatures start to fall, the moisture in the air cools off and ends up on the ground. During late spring and early fall morning, you’ll notice dew on plant leaves and other surfaces.
But as winter approaches, the water cools off below the dew point and transforms into frost. This happens when temperatures are around 33°F to 36°F, and there’s enough humidity in the air. You can expect minor damage to plants.
Right after frost, as temperatures continue to fall, we have freeze. The freeze happens when we reach 32° and below. These temperatures cause greater damage to your garden.
We experience hard freeze at or below 25°F. This weather is deadly to almost all plants in your garden and requires pipe protection. Depending on the length of the hard freeze, it can even kill hardy perennials.
What Is Considered A Light Freeze
The light freeze occurs at 32°F to 29°F and doesn’t cause significant harm to your garden. Delicate vegetation like crops might suffer some damage. Of course, you need to protect your plants; bring the potted ones indoors, but the hardy plants will manage outside just as well.
Hard Freeze Meaning
While frost is essentially the condensation and freezing of moisture in the air, a hard freeze can happen without a trace. There has to be a cold mass of air in the area for a hard freeze to happen, usually moved by strong winds.
Along with the temperature below 28°F and the lingering cold air, the ground and all surfaces freeze. When this condition lasts at least 2 hours during the day or night, it’s considered a killing freeze. Depending on when the hard freeze happens, it can kill the plants or disturb the germination process in trees.
If you speak to an experienced gardener, they’ll probably remember a year when hard freeze destroyed their crops.
When Can You Expect Hard Freeze
We can’t predict hard freeze. It’s evident that it happens as soon as temperatures drop below 30°F but following the weather forecast is your best bet. Follow the day temperature; the higher it is, the lower the chances for a hard freeze at night.
A heavy cold wind prevents warm air from settling over the ground and speeds up the freezing process. Pay attention to the sky too. A hard freeze is less likely to happen on a cloudy night. Clouds slow down the cooling as the sun sets and prevent freeze.
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Which Zones Experience Hard Freeze
USDA Hardiness zones 2 to 7 have a history of low winter temperatures, so they’re most likely to experience a hard freeze. But zones 8 and 9 are not excluded, even though they have higher average winter temperatures.
Winter temperatures never fall below 50°F in California, Florida, Arizona, Texas, Georgia, Louisiana, Alabama, Mississippi, South Carolina, and Nevada.
Your Garden and The Freeze Weather
Hardy crops don’t have trouble surviving mild winter in your garden. In fact, some of them, like peas, should be planted right before the freeze. Check the plant’s resistance before planting it in the fall or early spring. How suitable is your new plant for your Hardiness Zone?
Some plants survive winter just fine and won’t be affected much from an occasional hard freeze. If you can’t be bothered with protection, switch your garden to hardy crops like spinach, broccoli, leeks, kale, cabbage, brussels sprouts, peas, arugula, mustard greens, and onions.
Semi-hardy crops could also withstand a freeze, depending on how long and how often it happens. Try your luck with cauliflower, endive, lettuce, and celery.
Plants That Need Protection
Even light freeze takes its toll on all crops above ground. However, hard freeze causes damage beyond repair. Zucchini, eggplants, tomatoes, okra, peppers, and cucumbers are some of the most tender plants.
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Have You Considered Protecting Your Garden From Hard Freeze?
Protecting your crops is a must, even if most of them are hardy. Use mulch to insulate the roots and ground around the plant. This will help retain heat and moisture without freezing.
Pick a suitable cover that will trap the heat from the daily sun and won’t let cold air penetrate. Build a frame to allow the crop to grow in height and keep the cover from collapsing over the tender stems. Then cover with garden fleece or blanket. Finish with plastic foil, secured with rocks.
If your plants are tiny, cut a large plastic bottle in half by the length and cover them.
Cover the plants before you experience the hard freeze and before sunset. Expose them during the day to get the necessary air circulation and sunlight.
Can You Save A Plant After Hard Freeze?
Freeze damage is characterized differently in each plant. Even if they’re perennials, tender crops won’t survive a hard freeze. Hardy crops, as well as roots, can suffer root damage. Scratch the tree; if it’s green under the bark, it means it’s still doing well. Remove any freeze-damaged pieces in spring and fertilize the plant to boost healthy growth.
Bottom Line: What Is Considered A Hard Freeze
The hard freeze happens when temperatures fall below 28 and stay in the low twenties for over 2 or 4 hours. The hard freeze, unlike the frost, it’s extremely damaging and can kill off a significant part of the vegetation in your garden.
To avoid empty garden beds in spring, protect your crops and bring in your potted plants. Closely follow the weather forecast to avoid being too late.