What is the Grassland Temperature Sum (GTS)?

The Grassland Temperature Sum, or GTS for short, is a well-established tool from agriculture that beekeepers have long used too, to estimate when the season is about to start.

What’s behind it

Starting January 1st, the GTS adds up the positive daily average temperatures, day by day. Once this running total reaches a certain threshold, experience shows the first major bloom and forage period of the year is about to begin.

Why it matters to you

Instead of relying on a fixed calendar date, the GTS helps you estimate when to start swarm-prevention checks or when your colonies are about to begin bringing in nectar — without needing an exact date, just based on the actual weather so far.

How to use the GTS in the app

For each apiary, the app shows you the current GTS value along with a forecast of how it’s expected to rise over the coming days.

Recording your own reference points

Add your own observations to a timeline, for example “Snowdrops blooming” or “First willow blossom.” That way you can compare, year after year, whether nature is running earlier or later than usual.