Know Your Frost Dates

First and Last Frost Dates

Knowing your first and last frost dates is important for planning your butterfly garden.  Planting too soon in the spring can harm plants with a late spring freeze, and the first frost in the fall may damage newly planted plants if they are not established and ready for winter. Of course, some frosts don’t follow the expected timeline.  Planning is necessary, but so is keeping an eye on the weather.

Enter Your ZIP

Many gardening and weather sites have calculators for frost dates based on your ZIP code.  We use the database from the Old Farmer’s Almanac.  Enter the location on their website to discover your estimated first and last frost. Other sites like weather.gov provide detailed forecasts that help in your scheduling.

When to Plant Based on Frost Dates

Early Spring:  When we send young, greenhouse grown plants, we recommend planting after your last spring frost.  Our plants think it is spring and will be shocked by frost.  While you can take steps to protect them from unexpected and unusual late season frosts, it’s best to only plant after you’ve said goodbye to freezing temperatures.

Summer: Most locations have no fear of frost in the summer.  Your biggest concern will be heat and rain.  We will be sending plants that are mature enough to handle the season’s weather, but you may need to supplement water if you have a dry spell.

Fall:  Fall is a great time to plant perennials that will bring joy in the spring.  The trick is to establish them before winter comes.  We recommend planting at least one month before your first frost. Some recommend 6-8 weeks before the frost. Once the roots are established and the plants store enough energy for the winter, they are ready to go dormant and wait until spring to grow again.  If you live where you don’t have a typical winter, frost may not be an issue, but the change in day length may impact growth.

Seeds

Frost on a milkweed seed.

When planting seeds, check if the seeds need cold stratification.  Fall sowing is a great option for seeds that need to experience winter before germinating. If you are starting them in the spring, you will need to artificially cold stratify the seeds.  Spring sowing should be done after your last frost.  One way to extend your growing season without exposing young seedlings to the shock of a freeze is to start your seeds early indoors and then transplant them once the risk of frost has passed.  When sowing later in year, you’ll need to do so far enough in advance for them to grow and get fully established before your first frost.  The plants will need mature roots to survive the winter weather.

Changing Weather

Checking the estimated frost dates is helpful in planning your garden.  The dates are adjusted over the years to include current data, but they are still just estimates.  Use the frost dates as starting points and then adjust depending on the current weather trends.

Happy gardening!