Knowing your last frost date can help you plan a successful growing season. Spring fever can sometimes result in gardeners having an irresistible urge to get out and plant sooner than they should. The air is clean and crisp, the sun is bright, and those seeds and seedlings need to get in the ground, right? Well, maybe…
Before you succumb to that urge to sow those seeds and plant your seedlings at the first hint of spring, it would be wise to check the average last frost date for your area. Otherwise, you may be opening yourself up for disappointment. Take heart, though, because checking the date is easy and there are last frost date workarounds that allow you to start your plants early if you want.
What does last frost date mean?
Frost is a layer of tiny ice crystals that form on the ground and on plants when surface temperatures drop to at or below freezing. It can damage or kill plants, especially young ones.
The predicted last frost date for any given geographical area is the date in the spring when, based on historical data, the last frost of the year might occur. Because the prediction is an estimate based on historical data and because weather patterns often change, there’s no guarantee that you will not experience another frost after that date. The last frost date is a guideline for gardeners.
What is the last frost date for my area?
There are online resources that allow you to quickly find the last frost date for your area. You can check out our frost maps showing estimated last frost dates for spring as well as expected first fall frost dates.
The National Gardening Association offers an easy-to-use tool that allows you to enter your zip code and click a button to display a list of dates and probabilities for temperatures near, at, or below freezing for your area.
The National Oceanic and Atmospheric Administration (NOAA) uses a color-coded frost map to provide you with last freeze date predictions for different regions of the United States. Based on these predictions, you can get a good idea of when the last frost date of spring will occur in your immediate area.
When to plant based on the last frost date
The last frost date for your area will help you decide when to plant in the spring, but, as mentioned, weather patterns change and these dates are based on averages. If your winter has been especially cold, you may want to wait a week or so past the predicted last frost date before planting.
The backs of most seed packets have date range information for planting in specific regions. Vegetable garden seed packets also provide “days to harvest” information along with growing season date ranges. You can use this information to choose your planting dates. If, for example, a lettuce seed planted today will produce a harvest at around 45 days and your region’s growing season for this plant is four months, you can afford to wait several weeks past the estimated last frost date before planting.
Working around the last frost date
For those ambitious gardeners who just can’t wait to get things growing again after winter, we have a few tips to jump-start your spring gardening:
1. Work around the last frost date by starting your plants indoors or under shelter. This works whether you start them from seeds or want to increase seedlings’ heartiness before transplanting them into the garden.
2. Choose plants that enjoy cooler temperatures. Flowers such as pansies, sweet peas, sweet alyssum, primula, and cyclamen are at their best in the cooler temperatures of spring. Enjoy the earliest possible harvest by starting with these plants in your vegetable garden: lettuce, cabbage, radishes, peas, and bunching onions.
3. Cold frames are a great option for starting plants outdoors in the shelter of what is really a miniature greenhouse. Cold frames are not difficult or expensive to build and they allow you to start seedlings early or harden off plants that you’ve started indoors. If you’d rather start your plants indoors, you’ll need plenty of light. Even if you’re short on window space you can use grow lights to start your garden indoors.
Can the frost date change every year?
Remember that a last frost date is an estimate and is not set in stone. Assuming that you can plant the day after your final frost date, and be guaranteed success, could be a mistake. Check your growing seasons and the maturity dates for the flower and vegetable varieties you want to grow. Also, consider how harsh your current winter has been and check your local weather forecast before you choose your planting dates.
If you’re short on garden space and planning to grow your flowers and vegetables in containers, you’ll want to be especially careful about waiting to plant after the last frost date since plants in pots are more vulnerable to freezing. For tips on successfully growing plants in containers see our article, All About Container Gardening.
Check the frost map and start planning your spring gardening.