Goldenrod is Blooming in New York, which according to an 'Old Farmer’s Rule,' means the frost countdown has begun.

Have you noticed all the goldenrod starting to pop up around New York?

Those bright yellow flowers are more than just a late-summer splash of color. According to an old farmer’s rule highlighted by the Farmers’ Almanac, when the deep yellow flowers bloom, the first frost is roughly six weeks away.

So if you're seeing those first golden-yellow blooms right now, the old saying says we may have officially started the countdown to colder nights. And if you're me, you are crying at the thought of cold mornings.

The Farmers’ Almanac calls it a long-standing piece of farm folklore: “Goldenrod blooms, frost follows in six weeks.” It isn't meant to be an exact scientific forecast, but the timing can be surprisingly close in many parts of the country.

And there is actually some science behind why goldenrod seems to know when fall is coming.

Goldenrod is a photoperiodic, or short-day, plant, meaning its flowering is influenced by the changing amount of daylight. So, as summer winds down and the days become shorter, the plant responds to that seasonal shift and begins its flowering cycle.

That doesn't mean the plant can predict the exact date of the first frost. Weather still gets the final vote. A warm September can push frost later, while an early cold snap can move it up. But goldenrod's flowering happens during the same seasonal transition when nights are getting longer, the sun is lower in the sky and temperatures are beginning their slow march toward fall.

So that old farmer's rule isn't necessarily about goldenrod predicting frost. It's more like the plant is responding to the same seasonal clock that tells us winter is looming.