Data and calculations
Garden Dream methodology
What our tools calculate, which data they use and where their certainty ends.
Weather data source
Forecast and archive values come from Open-Meteo for the selected coordinates. They are gridded weather-model values, not readings from a sensor in the garden. Freshness depends on provider availability.
Frost dates
For the five most recent complete calendar years, we identify the last spring and first autumn day whose daily minimum was at or below 0°C, then display the median valid date. It is an archive-based estimate, not a station climate normal.
Spray window
Forecast hours pass a conservative screen for rain, wind, gusts and temperature. The result only describes weather suitability; the product label, crop stage, local law, buffer zones and neighbours remain decisive.
Growing degree days
Daily GDD is max(0, (daily maximum + daily minimum) / 2 − the selected base). We sum from 1 January using archive data through the latest available day and forecast data for the next week.
Chill hours
The simple model counts archive hours from November through March with air temperature from 0°C through 7.2°C. Cultivar requirements and alternative chill models can produce different answers.
Pollinator activity
We highlight forecast daylight hours that are comparatively warm, dry and calm. This is a weather opportunity signal, not a count or forecast of insects at the site.
Uncertainty and decisions
Microclimate, shelter, elevation, soil and model performance can change conditions in a particular garden. We present estimates as decision support, not guarantees. For costly or safety-sensitive decisions, check the local official forecast, the label and observations on site.