Fort Collins, Colorado
Mowing
When you can next cut it, and the best slot this weekend.
Best weekend slot
Monday 10am–midday
Verdict: Good
cool — 26°C
Next mow
Today 7pm–8pm
Verdict: Good
heat stress — 27°C
The next 10 days
Column height is how mowable the day is; the lighter band is the best stretch within it. The line is soil temperature at 6cm. It crosses the seeding threshold inside this forecast.
12.5°C — seeding
Soil at 6cm 27.9°C cooling to 0.0°C
Wednesday 2 September: Good. 7pm–8pm — heat stress — 27°C
Wednesday 2 September · 7pm–8pmConfident
7pm–8pm — heat stress — 27°C
- Good:Grass wetness
- Grass dryno rain since Tuesday
- Good:Ground firmness
- Ground firm1mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.90
- Poor:Temperature
- Heat stress27°C
- Good:Wind
- Wind light5 km/h
- Sociable hours
- A bit early or late, but fine
Limiting factor:temperature
Thursday 3 September: Good. 8am–midday — no rain since Tuesday, ground firm
Thursday 3 September · 8am–middayConfident
8am–midday — no rain since Tuesday, ground firm
- Good:Grass wetness
- Grass dryno rain since Tuesday
- Good:Ground firmness
- Ground firm1mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.85
- Poor:Temperature
- Temperature13°C
- Good:Wind
- Wind light5 km/h
- Sociable hours
- A bit early or late, but finestarts when it stops being antisocial
Limiting factor:none
Friday 4 September: Good. 8am–11am — no rain since Tuesday, ground firm
Friday 4 September · 8am–11amConfident
8am–11am — no rain since Tuesday, ground firm
- Good:Grass wetness
- Grass dryno rain since Tuesday
- Good:Ground firmness
- Ground firm1mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.69
- Poor:Temperature
- Temperature17°C
- Good:Wind
- Wind light9 km/h
- Sociable hours
- A bit early or late, but finestarts when it stops being antisocial
Limiting factor:none
Saturday 5 September: Good. 8am–10am — growing steadily — growth potential 0.35
Saturday 5 September · 8am–10amConfident
8am–10am — growing steadily — growth potential 0.35
- Good:Grass wetness
- Grass drydried off since a shower 5 hours ago
- Good:Ground firmness
- Ground firm0mm rain over the last week
- Good:Growth
- Growing steadilygrowth potential 0.35
- Poor:Temperature
- Temperature22°C
- Good:Wind
- Wind light5 km/h
- Sociable hours
- A bit early or late, but finestarts when it stops being antisocial
Limiting factor:growth
Sunday 6 September: Good. 11am–1pm — heat stress — 27°C
Sunday 6 September · 11am–1pmReasonably confident
11am–1pm — heat stress — 27°C
- Good:Grass wetness
- Grass dryno rain since Saturday
- Good:Ground firmness
- Ground firm1mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.57
- Marginal:Temperature
- Temperature23°C
- Good:Wind
- Wind light7 km/h
- Sociable hours
- Fine by the neighboursstarts once the rain has passed
Limiting factor:temperature
Monday 7 September: Good. 10am–midday — cool — 26°C
Monday 7 September · 10am–middayReasonably confident
10am–midday — cool — 26°C
- Good:Grass wetness
- Grass dryrain earlier today
- Good:Ground firmness
- Ground firm1mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.56
- Poor:Temperature
- Temperature21°C
- Good:Wind
- Wind light6 km/h
- Sociable hours
- Fine by the neighboursstarts when it stops being antisocial
Limiting factor:temperature
Tuesday 8 September: Good. 8am–1pm — rain earlier today, ground firm
Tuesday 8 September · 8am–1pmReasonably confident
8am–1pm — rain earlier today, ground firm
- Good:Grass wetness
- Grass dryrain earlier today
- Good:Ground firmness
- Ground firm1mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.63
- Marginal:Temperature
- Temperature21°C
- Good:Wind
- Wind light1 km/h
- Sociable hours
- A bit early or late, but finestarts when it stops being antisocial
Limiting factor:none
Wednesday 9 September: Good. 8am–1pm — rain earlier today, ground firm
Wednesday 9 September · 8am–1pmReasonably confident
8am–1pm — rain earlier today, ground firm
- Good:Grass wetness
- Grass dryrain earlier today
- Good:Ground firmness
- Ground firm1mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.69
- Marginal:Temperature
- Temperature21°C
- Good:Wind
- Wind light6 km/h
- Sociable hours
- A bit early or late, but finestarts when it stops being antisocial
Limiting factor:none
Thursday 10 September: Not worth it. No — ground frozen.
Thursday 10 SeptemberLow confidence this far out
No — ground frozen.
- Marginal:Grass wetness
- Grass dryrain earlier today
- Good:Ground firmness
- Ground firm4mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.87
- Marginal:Temperature
- Temperature19°C
- Good:Wind
- Wind light3 km/h
Limiting factor:grass wetness
Friday 11 September: Not worth it. No — ground frozen.
Friday 11 SeptemberLow confidence this far out
No — ground frozen.
- Marginal:Grass wetness
- Grass dryrain earlier today
- Good:Ground firmness
- Ground firm6mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.88
- Good:Temperature
- Temperature20°C
- Good:Wind
- Wind light4 km/h
Limiting factor:none
Growth
How fast it is growing, and when it will need cutting again.
0.90Growing strongly
Growth potential, 0 to 1 — the turf-industry measure of how fast grass can grow at today's temperature and day length.
Putting on about 5.4mm a day. A lawn cut today would be ready for another in around 4 days.
Worked out from the PACE Turf growth potential model and day length —how and why.
What this means right now
Warning: Too warm to seed
Too warm to seed — the soil is heat-stressed. Wait for it to cool.
Warning: Heat stress
Wednesday 2 September gets hot enough to stress the sward. Mow early or late, and raise the height.
Seeding
Soil temperature at germination depth, and when the window opens.
Soil temperature
82°F27.9°C
at 6cm — germination depth
Cooling over the next 10 days.
Too warm to seed — the soil is heat-stressed. Wait for it to cool.
An independent estimate from air temperature gives 22.5°C, 1.6°C away. Treat the figure as approximate.
Most cool-season lawns in the northern US and Canada are bluegrass, tall fescue, or a mix of the two. We assume that, and use12.5°C as the seeding threshold.
I know what grass I have
The differences are small. Ryegrass is the quickest off the mark; bluegrass is the slowest and wants the warmest soil. Everything else sits between.
| Species | Soil temp | Days |
|---|---|---|
| Perennial ryegrass | 8°C | 5–10 |
| Red / chewings fescue | 8–10°C | 10–14 |
| Tall fescuelikely yours | 10–12°C | 10–14 |
| Browntop bentColonial bentgrass | 10–12°C | 14–21 |
| Smooth-stalked meadow grassKentucky bluegrasslikely yours | 12–13°C | 14–28 |
Feeding
Why timing decides whether a feed does anything at all.
Coming in the app
Grass takes up nitrogen when it is growing. Feed a lawn that has stopped and most of it washes past the roots — which is why timing beats product choice.
Right now this lawn is growing well enough to use a feed.
The app will work out the actual feeding windows for your lawn — along with weed control, scarifying and moss treatment — and tell you when they open without you having to check.
Fort Collins, Colorado in detail
Soil temperature at 6cm in Fort Collins, Colorado is currently 27.9°C, and falling about 24.1°C over the next 10 days. That depth matters because it is where grass seed sits and where roots start working, and it lags air temperature by days — which is why a warm afternoon here tells you very little on its own.
Lawns in this area are typically Kentucky bluegrass with tall fescue, the usual mix for cool-season lawns at this latitude. That blend needs the soil to hold above 12.5°C before seed germinates reliably. Too warm to seed — the soil is heat-stressed. Wait for it to cool.
8 of the next 10 days are good mowing days. The best weekend slot right now is Monday 10am–midday, on the basis that cool — 26°C.
The next recommended window in Fort Collins opens at 7pm on Wednesday 2 September, and holds while conditions stay put. Underfoot, the ground reads as firm after 1mm rain over the last week.
Forecast from Open-Meteo, refreshed hourly. Soil temperature is modelled, not measured — how that works and where the thresholds come from.