All You Need to Know About Frost Dates

Like the name suggests, frost dates are date ranges within which you can expect the first or last freeze of the season. Weather patterns differ greatly from year to year— so the frost dates in your area will change almost every year. Anyone who’s gardened in a colder zone likely knows just how much damage that frost can do to a garden, so keep these dates at the front of your mind when planning for spring planting!

Almanac’s frost date estimations can be found here. Simply enter your city or zip code into the search bar.

A few things to keep in mind about frost dates:

Before we get into the dates themselves, there are a few things that you’ll want to keep in mind about how frost dates work and how they’re decided upon. The more you know about what they mean, the more useful they are to you as a gardening tool!

• Frost dates are not certainties, they are estimates based on historical climate data. They tend to be pretty accurate, but it’s next to impossible to predict them will full confidence. If you’re planting something that is very sensitive to frost then it may be a wise idea to wait a bit after the last frost date has passed, so you can see how the weather is developing.
• In line with the last tidbit, keep an eye on your local weather. Unexpected cold snaps happen, and you don’t want to be caught off-guard.
• The ground is colder than the air. This is factored into frost date determination. Even if the air temperature is above freezing, the ground can still be significantly colder.
• Microclimates play a big role in your gardening experience, so keep in mind how your or your neighbor’s gardens have performed in past springs.
• There are different “levels” of frost. The Almanac splits them up into three sections:
  • A light freeze occurs between 29 to 32 degrees Fahrenheit.
    • Some plants, usually those native to colder climates, will fare fine at this temperature. However, it can also easily kill more delicate plants. When in doubt, wait it out.
  • A moderate freeze is defined as temperatures within the range of 25 to 28 degrees Fahrenheit.
  • A hard frost is when temperatures fall below 25 degrees Fahrenheit.
    • Damage to plants happens faster, and is more severe, as the temperature falls.
    • Colder weather often comes hand in hand with wind and precipitation. These can contribute greatly to frost damage, especially when the plant is already in a weakened state. 

Can plants be protected from frost?

Yes, but because they’re so many factors at play, these methods have varying degrees of success. Still, if an unexpected frost comes out of nowhere then minimizing damage is ideal.

• Move containers indoors if possible. It might be a pain to do, but you’re saving yourself heartache in the long run. 
• Row covers and garden fleece can act as miniature greenhouses, trapping warmth inside and keeping freezing air or wind at a distance. They’re great for small, regularly shaped areas of the garden, but can quickly get difficult to work with for bigger areas. If you’re really in a pinch, try using an old bedsheet. It’s better than nothing! Be sure to use stakes if you try this, as you don’t want it to be touching the plants.
• Mulch can act as a wonderful insulation, especially if the expected freeze is a mild one. A two-inch layer is usually a good place to start, but you can change this up depending on the situation. This will also protect worms and other life within the soil, which is essential to a healthy garden.
• Water your plants both before and after a frost. Wet soil traps heat far better than dry soil, keeping the ground warmer. After a frost, any water in the ground that has frozen isn’t going to be accessible to your plants. They’ll appreciate a fresh supply of liquid.
• Prune after a frost— but do so at the right time.
  • Woody plants can be damaged if pruned too soon, so wait until you start to notice new growth before removing damaged areas. If you think an area is damaged, but aren’t sure, then cut off a tiny bit of the outer bark. If it’s green underneath then it should be healthy, while brown or black indicates damage.
  • Non-woody plants can be trimmed sooner, but you only really need to get rid of anything that looks to be decaying.
• If an unexpected snow accompanies the freeze, be sure to clear it off from delicate plants as soon as you can. Not only is snow cold, but the weight of it can cause harm too.

When it comes to frost, think ahead.

Paying attention to frost dates and local weather is essential— but be sure to also consider it when you’re planning out your garden.

• Sunny areas warm quickly, but areas with tree cover can provide small pockets of insulation and snow/ wind protection.
• Rocks, walls, and shrubs can also help to block wind.
• Planting things close together can help them trap heat, especially near ground level. Of course, planting things too close together comes with its own issues.
• Planting on slopes can help to move cold air away from plants, with south-facing slops usually being most ideal.
• Plant your most delicate varieties last. It might be hard to fight the excitement of seeing it in the ground, but it could be worth it in the end!

Thank you for reading, and good luck keeping Jack Frost out of your garden! For the latest updates on all things Proven Winners Direct™, be sure to subscribe to our email list!

Happy Planting!