In your own garden, you might have all sorts of gorgeous annuals, tropical plants, vegetables, and herbs that you would probably want to enjoy for as long as possible before the first frost date. As soon as air temperatures drop to 36 degrees Fahrenheit or even below, the leaves of such plants will wither and blacken, bringing your garden party to a halt.
Knowing the average first frost in your region could help you get ahead of those potential issues, giving you enough time to bring frost-sensitive plants indoors and clean up your garden for the winter.
Luckily, there are many resources out there to help you figure out when you should do that. Even more so, we made a list here so you won’t have to wander through the internet for too long!
First freeze map and average first frost dates
First things first: you should find where you live in the interactive map attached here. It shows six different time periods, each of them spanning about a month from the end of June all the way to the end of December.
Then, each of these is color-coded to the regions where the first frost could take place during that specific range of dates. For instance, if you live in Ohio, you could get your first fall frost sometime between September 30 and October 30.
Moreover, if you would like to narrow down your window of time, there’s a handy online tool made by the National Gardening Association that will help you find the first frost dates depending on your ZIP code.
It generally uses weather data from the National Centers for Environmental Information, but it also presents it in such a way that you can only see the numbers that apply to that area.
Find your USDA Plant Hardiness Zone
Another great resource is the USDA Plant Hardiness Zone Map. It shows exactly how cold your region can potentially get during wintertime. You can also search by ZIP code or your state to find the desired USDA zone.
Your zone number can help you know better which plants will be hardy in your area, and which ones are likely to survive your winter weather, including your first fall frost. The current version of the USDA map was made in 2012 and it’s also the latest in a very long line of maps showing averages of the coldest winter temperatures.
Microclimates and average first frost dates
Your yard, and even a particular spot in it, could experience frost way before others in your neighborhood. How come? Well, that’s due to the microclimates, which are provoked by factors that affect air temperatures near the ground, like elevation.
For example, if you live at the bottom of a hill, slope, or even valley, the cold air will flow down to you, which will make your property colder than other areas in your neighborhood, and your first frost will happen sooner.
On the same note, a sheltered spot might not have frost until several weeks after other areas. You should keep this in mind when a light frost is expected, as your garden might escape the phenomenon until temperatures drop even more.
Plants that won’t make it until the first frost date
Annuals
The wide majority of annuals and tender perennials will probably die off when Jack Frost comes into the neighborhood. If this year we’re talking about a light frost, sometimes you can keep your geraniums or bedding plants for longer, especially if you cover them overnight with an old sheet or towel.
Uncover them when temperatures rise the following day. This goes for your pots of fall mums, as well, which can definitely take a light frost but not a hard freeze.
Container plantings
You should check the tags of any plants you’re growing in containers. Those listed as USDA Zones 9 to 14, like coleus, elephant ears, and begonias can be easily brought into a garage or shed before a light frost. When the weather warms up once again, you can simply move them back outside to enjoy them for longer.
If you like to move your houseplants like your philodendrons and tropical ferns outside during summertime, you should know that they might end up damaged when nighttime temperatures cool to 45 degrees Fahrenheit or 50 degrees Fahrenheit. If you want to keep them, you should bring them indoors well before the first frost sets in.
Herbs and summer vegetables
There are plenty of herbs out there, as well as summer vegetables, that simply won’t tolerate much frost. So harvest those tomatoes that are still up and going (even the green ones), cut all the bouquets of dahlias, zinnias, and marigolds, and try to make pesto with the last of your basil.
Also, try to pickle the cucumbers, or even pick a pint of peppers when a cold snap is coming. Then, wave goodbye to your summer garden friends, cut down the plants, and carefully put them in the compost pile.
It’s definitely more pleasant to do the cutting before a freeze will turn these plants black and slimy. You can also leave cool-season crops such as lettuce and potatoes a bit longer, but harvest the produce before heavy frost at 28 degrees Fahrenheit or lower will start to damage them.
simple ways to protect your plants from frost
Well, as we discussed, an icy forecast can pose a lot of trouble for some plants in your garden, unless you know exactly how to protect them from frost. Temperatures that go as low as 30 degrees Fahrenheit could easily kill vegetable crops and tender summer annuals such as petunias and begonias.
Even if you can’t grab a jacket for your cucumber vines or pots of marigolds, this guide could help you protect your plants, especially when frost occurs. Besides, you could find out which plants need frost protection and when you should take immediate action.
More about frost
When weather forecasters release a frost advisory in late spring and early fall, that’s when you know you need to protect your annuals and other vulnerable plants. You might even think a frost doesn’t happen until temperatures drop to the freezing point (which would be 32 degrees Fahrenheit), but in reality, the cold weather phenomenon sets in when temperatures fall somewhere between 32 degrees Fahrenheit and 36 degrees Fahrenheit.
A frost can also be quite light or hard, as a light frost around the upper end of the temperature range could easily kill the tops of tender plants, as the lower parts are still green. Also, a very difficult frost takes place when temperatures hover around 32 degrees Fahrenheit for a couple of hours, which generally kills all above-ground parts.
What’s the difference between freeze and frost
Below 32 degrees Fahrenheit is mainly seen as a freezing temperature, which is definitely more destructive than a frost. Tender plants, like tropical houseplants and geraniums, are terminated when the air temperature stays below 32 degrees Fahrenheit for a couple of hours.
A freeze warning often signals the end of the growing season in fall, especially since temperatures are low enough to kill off all the annuals and trigger dormancy for those sturdy perennials, trees, and shrubs. Freeze warnings in spring also signal the dire need to bring tender plants inside, especially until temperatures warm up.
When you should cover the plants against frost.
When low temperatures like 36 degrees Fahrenheit to 32 degrees Fahrenheit are in your forecast, that’s when you know it’s time to cover your tender plants. Since low-lying areas within a landscape can experience slightly lower temperatures, you might want to consider converting your plants, just to be safe.
If you can, try to cover them in the afternoon before temperatures start dropping as the sun goes down. Besides, it’s way easier to get covers in place, especially if you have some light to see exactly what you’re doing.
Which of these plants needs frost protection?
Technically, annual plants that fruit and flower in warmer temperatures are also more sensitive to cold weather. Just think about the vegetables and herbs you harvest in midsummer and which annual flowers are most colorful during the hotter temperatures.
Frost protection for plants like these ones is much needed, either in spring when they’re quite young and tender or throughout the fall if you want to keep them going for as long as possible before winter sets in.
Many of those plants come from frost-free tropical regions of the world, so you should play it safe and make plans to protect them whenever temperatures dip below 40 degrees Fahrenheit.
On the other hand, perennials (garden plants that come back year after year), shrubs, and trees can generally withstand a sudden drop in temperature as long as they’re healthy and hardy in your region.
A spring freeze could easily damage developing fruit and destroy flowers, but these plants will survive either way. Some edible plants, like peas, lettuce, and onions, but also cauliflower, broccoli, radish, and cabbage are especially hardy.
These cool-season vegetables can easily withstand temperatures as low as 26 degrees Fahrenheit. Even hardier crops such as beets, Brussels sprouts, carrots, collards, kale, parsley, and spinach can easily shake off temperatures in the low 20s. A couple of cold-tolerant flowers such as pansies and sweet alyssum don’t even mind frosty weather.
Protecting plants from frost
If you can figure out how to efficiently protect plants from frost, you first need to categorize them depending on size and quantity. Luckily, we gathered a bunch of strategies that might help with that:
Move containers indoors
When you can, bring all the tender plants indoors. Small container gardens and plants that are still in their nursery pots are mainly easier to move indoors, at least temporarily. A heated location isn’t always needed.
Moving plants to a space such as a garden shed or a garage could provide enough protection during a frost. But when low temperatures are close to freezing point, you should love your plants to an insulated indoor location
Bring out the blankets
Make sure you round up all the old bedspreads, blankets, and large towels, then carefully drape them loosely over plants, supporting the material with stakes as needed. Also, make sure the plant cover extends to the ground in all the needed places to effectively create a small dome of insulation.
If the wind is an issue, anchor the fabric to the ground with some bricks, stones, and any other heavy object. Woven fabric will provide better protection than plastic or paper. You can easily add plastic sheets on top of your fabric layer to shield it from precipitation that might take place.
Remove the coverings by midday so your plants don’t overheat, but also keep them handy because there’s often more than one frosty forecast per season.
Use a cloche
This is a French term for “bell.” A garden cloche is generally a rounded cover that acts just like a mini-greenhouse around a single tender plant. One of the easiest garden hacks requires making a milk jug cloche from the bottom of a gallon-size jug, then placing it over a plant and pushing the bottom of the jug about an inch deep in the soil.
Then, carefully tie the jug’s handle to a nearby stake to prevent it from blowing away. You can keep the jug lid closed during nighttime for full protection, but you should remove the lid to vent the cloche during the day to avoid overheating the plant.
Water them well
Well, did you know that moist soil can easily hold four times the amount of heat a dry soil would? The moisture in the soil can conduct heat all the way up to the soil surface, warming the area around the plant as much as 2 degrees Fahrenheit to 3 degrees Fahrenheit.
When cold weather is forecast, that’s when you know you can water your plants well. Besides watering, you can add a cloche or blanket for another layer of protection.
Add some mulch
A good old thick layer of mulch, for example, shredded bark or even compost, can definitely help insulate tender plants. You can cover the entire plant with mulch the night before low temperatures are forecast.
You can also remove it when the weather warms up again. Messy and labor-intensive, mulch might not be the ideal option for large planting spaces. You should keep this method for a few small but sturdy plants. Also, don’t try this method with fragile seedlings, because our bet is that it won’t work the same.
Pamper the trees and shrubs
Your trees and shrubs will definitely have an easier time getting through winter if you make sure they stay in good shape. For both evergreen and deciduous species, one of the most essential things is to give them enough water before the ground goes on and freezes, especially if autumn leaves them all dry.
When it comes to trees and shrubs planted in the fall, we’d advise you to spread organic material, like chopped leaves, up to 6 inches thick around the base, and make sure the mulch doesn’t touch the stems.
This will help keep moisture in the soil (as plants need water even if it’s winter), and also protect the roots from freezing and thawing. You can also trim away damaged and diseased limbs to prevent snow and wind from worsening these issues. As for young evergreens in exposed locations, you might as well shield them from drying winter wind with a bunch of burlap screens or shade cloth shelters.
Bundle up the roses
Roses are probably in the top 3 most beautiful plants, so it’s fairly difficult to begrudge them the attention they need over the growing season. As cool weather brings on their dormant period, there’s one last thing you need to do: get them ready for winter.
Some types of roses are definitely hardier than others, so it’s fairly important to know beforehand which type of roses you have. As a group, hybrid tea roses are definitely the most vulnerable ones, especially when it comes to winter cold, and they need the most preparation.
As for the easiest ones, we would definitely name shrub roses. You need to make sure you give all of them enough water before the ground freezes, but also don’t fertilize or cut them back. If you want to protect the root balls from frost heaving, you need to pile up extra soil around their base.
For example, in Zone 6 and other, much colder areas, you can add a 6- to 12-inch layer of straw, leaves, or any other mulch on top of the soil mound, secured with some chicken wire.
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