When someone asks me to name a few of the topics in my book, my usual answer has been, “Oh, things like frost is more likely on a full moon.” There’s always a pause before the questioner says, “You mean that isn’t true?” A look at data, and thinking about the variety of topography in any single area, shows why this myth is made of moonbeams.
In the spring and fall, a frost is more likely to occur on clear nights. But several people have collected data of first and last frosts in their area and then compared it to the phases of the moon. They found no correlation between a full moon and frost. Even without this assessment of the numbers, common sense tells us that this folklore is fiction.
A quick online search of average first and last frost dates shows tremendous variation from one area to another. In Presque Isle, Maine, for example, the average first frost is on the 4th of September, while in Augusta it’s on the 22nd and in Bar Harbor it’s in early October. Other towns and cities in the state list additional days when their first freeze is likely. If frost was more likely on a full moon it stands to reason that those dates would be grouped more closely together.
We also know that the lay of the land has a great deal to do with how cold it gets. Just as the heat from the earth is rising on clear nights, the cold air sinks. So people who live in a valley are more likely to have a frost on such nights than those who live on the hillside. You might have even seen that low gardens in your yard will be frosted while other beds are not.
Moon myth-busters are fond of saying that it’s likely this belief began because clear, full moon nights make an impression on us. Over the ages, humans have marked the passage of time and the seasons by the phases of the moon and the full moon determines many religious calendars and celebrations. Perhaps as the seasons change, the full moon just seems more important.
Did You Know…
Many cultures and traditions give a special name to the full moon of each month. Here are some of them:
- January: “Wolf Moon”
- February: “Snow Moon”
- March: “Sap Moon”
- April: “Seed Moon”
- May: “Flower Moon”
- June: “Rose Moon”
- July: “Hay Moon”
- August: “Sturgeon Moon”
- September: “Harvest Moon“
- October: “Hunter’s Moon“
- November: “Frosty Moon”
- December: “Long Nights Moon”
If gardeners named the full moon, I think they would be something like this:
- January: “Seed Catalog Moon”
- February: “Internet Plant Shopping Moon”
- March: “First Trips to Garden Center Moon”
- April: “Plant Lust Moon”
- May: “Dirty Fingernails Moon”
- June: “Still Have Plants Waiting to go in Garden Moon”
- July: “Crabgrass Explosion Moon”
- August: “Ripe Homegrown Tomatoes! Moon”
- September: “Houseplants Back Indoors Moon“
- October: “Frost Kill Sadness/Relief Moon”
- November: “Pleased Not to be Weeding Moon”
- December: “Long Nights Moon”
This is an excerpt from Coffee for Roses: …and 70 Other Misleading Myths About Backyard Gardening by C.L. Fornari, available for purchase on May 16, 2014–two days after the full moon.