The science behind Turf Alert
Not a generic "mow weekly from March" calendar. Every alert comes from soil-temperature and water-balance physics, checked against 86 years of UK weather before we trusted it.
Growth, modelled properly
Grass growth is driven by soil temperature and day length, not just air temperature — so we track both.
Rainfall vs. evaporation
Rainfall in, evaporation out — the same soil-moisture accounting agronomists use.
Checked, not assumed
Every threshold has been tested against 86 years of UK weather before it was trusted.
What we measure
Every day, Turf Alert pulls weather data for your rough location: soil temperature, soil moisture, rainfall, and evapotranspiration (how much water is leaving the soil through evaporation and the grass itself). That's a richer picture than the air-temperature-only view most lawn advice is built on — soil temperature is what drives root and shoot growth, and it lags behind air temperature in ways that matter.
Two models
A growth model tracks how much your grass is growing day to day, based on soil temperature and daylight — mow alerts fire on accumulated growth, not a fixed weekly clock, so the interval stretches in a slow spell and tightens in a warm one. A water-balance model tracks soil moisture the way agronomists do — rainfall in, evapotranspiration out — so watering alerts reflect an accumulated deficit, not just "it hasn't rained in a while."
Checked against independent data
Internal consistency isn't enough — a model can be perfectly self-consistent and still wrong. So every threshold in Turf Alert has been checked against independent, external UK data:
86 years of weather data
Open-Meteo's archive goes back to 1940 for most UK locations, and every threshold is tested across the whole range rather than a convenient recent decade.
Matches the Woodland Trust's citizen-science data to within a day
The Woodland Trust's Nature's Calendar project has recorded the UK's first lawn cut of the year since 2000 — 34,000 records, averaging 19 March. Our model's predicted first mow lands on 18 March, a day off that independent dataset.
Reconstructed 4 of the UK's 5 worst droughts on record — unprompted
Ranking every year 1940-2025 purely by the model's own drought-stress numbers surfaces 1947, 1976, 1990, and 1995 among the worst — four of the most infamous UK drought summers on record, including the Great Drought of 1976. The model found them from raw physics, without ever being told which years to look for.
Cross-checked against declared hosepipe bans
The driest years the model identifies line up with dated UK hosepipe ban announcements — the water companies' own declared drought crises, not a model-internal opinion of what counts as "severe."
None of this makes the model perfect — weather forecasting and biology both carry real uncertainty, and we say so plainly in the terms. But every threshold behind your alerts has been tested against 86 years of weather, not picked because it sounded reasonable.