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What Are Frost Dates, and Why Do They Matter for Gardeners?

Cabbage covered in frost inside of a garden.
Amanda J Jackson/Shutterstock.com

Have you ever read the directions on a packet of seeds, and wondered what it means to plant before the last frost date? Before you start your garden this year, it’s important to know what frost dates are, and why they matter so you’ll get the best results.

Your delicate plants won’t fare well in frost, so staying on top of weather predictions is crucial as a gardener. Luckily, there are plenty of resources that can help you protect your plants from this enemy.

What Is a Frost Date?

A row of cabbage covered in frost.

If you start your garden with seeds, the packets are loaded with information, including the plant’s description, its best-by date, and planting directions.

The planting instructions also typically include when to plant the seeds based on the first and last frost dates. These dates play a vital role in your plant’s success, so planting according to these directions is crucial.

A frost date is the estimated date of weather conditions that could cause frost to form on the ground. Frost dates are important for gardeners because knowing when they are minimizes the risk of cold weather damaging or killing your plants.

The last frost date will guide you about when it’s safest to plant your seeds, and the first frost date will give you an estimated time of when to harvest your plants. Just remember, these dates are just estimates based on historic climate data, so there’s always a chance frost could occur before or after the provided dates.

How to Use Frost Dates for Gardening

An image from the Old Farmers Almanac vegetable gardeners handbook.
Old Farmer’s Almanac

Your frost dates are determined by the region in which you live. You can use this search tool on The Old Farmers Almanac site to find out what the estimated dates are each year.

After you type your zip code, or your city and state, you’ll see all of the following info:

  • Altitude
  • Last spring frost date
  • First fall frost date
  • Length of the growing season

This free printable planting calendar is another fantastic resource for planning your garden. It includes details about the best times to start seeds and transplant them, or when to plant them directly in the ground according to the frost dates.

From delicate herbs, like basil and dill, to hearty vegetables, like radishes and potatoes, you’ll get the best-estimated dates to take advantage of the best growing conditions.

For a more in-depth guide on growing veggies in your region, including essential references tables for the growing season, you’ll love The Old Farmer’s Almanac Vegetable Gardener’s Handbook. You’ll learn how to start seeds and save them for next year, plus, you get helpful, step-by-step instructions on developing your green thumb.

The Old Farmer's Almanac Vegetable Gardener's Handbook

An excellent guide for all gardeners.

Why Watching the Weather Is Important

An image of a raised garden bed with a plant cover place half way over ready to be fully placed on if cold weather comes in.
Trevor Clark/Shutterstock.com

Knowing your region’s first and last frost dates is helpful, but again, because these dates are estimated, it’s also crucial for gardeners to keep track of weather advisories. This is especially true now, as unpredictability seems to be at an all-time high in some areas.

Because the ground is colder than the air, frost dates are predicted based on air temperatures that reach 32 degrees Fahrenheit. This means you’ll see frost advisories when temps are between 33-36 degrees Fahrenheit.

According to the almanac, you’ll also see the following classifications of freeze temperatures, which have varying effects on plants:

  • Light freeze: This means temps will be 29-32 degrees Fahrenheit, which will kill delicate plants.
  • Moderate freeze: Temps 25-28 degrees Fahrenheit fall under this category and will damage most plants.
  • Hard freeze: Anything 24 degrees Fahrenheit or below. Temps this cold will heavily damage most vegetation.

So, just keep an eye on those temps during planting and harvest seasons, and you can prevent them from killing off all your hard work.

How to Protect Your Plants From Frost

Two images of the Agfabric frost protector plant cover.

An unexpectedly early or late frost can sometimes come into play and catch gardeners off guard. That’s why it’s always great to be prepared if you live in a region like New England, where the weather can be particularly unpredictable.

Plant covers are fantastic to have on hand because they’ll prevent the freezing air from directly contacting the moisture on your plants and creating frost.

Row covers, like these from Agfabric, create a greenhouse-like effect and keep your plants warmer, too, which is also helpful. They’ll also protect your vegetation from bugs, animals, and harsh winds.

Agfabric Plant Covers Freeze Protection

Save your plants from Jack Frost.

Whether you’ve just started gardening or have the greenest of thumbs, knowing the frost dates for your region can mean life or death for your plants. Armed with this important knowledge, you’ll be able to protect your precious vegetation all season and enjoy a delicious harvest!

Emilee Unterkoefler Emilee Unterkoefler
Emilee Unterkoefler is a freelance food writer, hiking enthusiast, and mama with over ten years of experience working in the food industry. Read Full Bio »
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