Merthyr Tydfil, Wales
Mowing
When you can next cut it, and the best slot this weekend.
Best weekend slot
Sunday 10am–2pm
Verdict: Good
ground soft in places — 35mm rain over the last week
Next mow
Today 2pm–8pm
Verdict: Good
ground soft — 60mm rain over the last week
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.
9°C — seeding
Soil at 6cm 18.0°C cooling to 14.4°C
Thursday 3 September: Good. 2pm–8pm — ground soft — 60mm rain over the last week
Thursday 3 September · 2pm–8pmConfident
2pm–8pm — ground soft — 60mm rain over the last week
- Poor:Grass wetness
- Grass dryrain earlier today
- Poor:Ground firmness
- Ground soft60mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.92
- Good:Temperature
- Temperature17°C
- Good:Wind
- Wind light17 km/h
- Sociable hours
- Fine by the neighboursstarts once the dew has burnt off
Limiting factor:ground firmness
Friday 4 September: Good. 1pm–8pm — ground soft — 53mm rain over the last week
Friday 4 September · 1pm–8pmConfident
1pm–8pm — ground soft — 53mm rain over the last week
- Marginal:Grass wetness
- Grass drydried off since a shower 4 hours ago
- Poor:Ground firmness
- Ground soft53mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.81
- Good:Temperature
- Temperature16°C
- Good:Wind
- Wind light12 km/h
- Sociable hours
- Fine by the neighboursstarts once the dew has burnt off
Limiting factor:ground firmness
Saturday 5 September: Good. 8am–8pm — ground soft in places — 46mm rain over the last week
Saturday 5 September · 8am–8pmConfident
8am–8pm — ground soft in places — 46mm rain over the last week
- Good:Grass wetness
- Grass dryrain earlier today
- Marginal:Ground firmness
- Ground soft in places46mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.61
- Good:Temperature
- Temperature11°C
- Good:Wind
- Wind light8 km/h
- Sociable hours
- A bit early or late, but finestarts when it stops being antisocial
Limiting factor:ground firmness
Sunday 6 September: Good. 10am–2pm — ground soft in places — 35mm rain over the last week
Sunday 6 September · 10am–2pmConfident
10am–2pm — ground soft in places — 35mm rain over the last week
- Good:Grass wetness
- Grass dryno rain since Friday
- Marginal:Ground firmness
- Ground soft in places35mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.85
- Good:Temperature
- Temperature14°C
- Good:Wind
- Wind light12 km/h
- Sociable hours
- Fine by the neighboursstarts when it stops being antisocial
Limiting factor:ground firmness
Monday 7 September: Good. midday–5pm — ground soft in places — 18mm rain over the last week
Monday 7 September · midday–5pmReasonably confident
midday–5pm — ground soft in places — 18mm rain over the last week
- Marginal:Grass wetness
- Grass dryrain earlier today
- Marginal:Ground firmness
- Ground soft in places18mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.63
- Good:Temperature
- Temperature13°C
- Good:Wind
- Wind light15 km/h
- Sociable hours
- Fine by the neighboursstarts once the dew has burnt off
Limiting factor:ground firmness
Tuesday 8 September: Not worth it. No — 0.3mm of rain falling.
Tuesday 8 SeptemberReasonably confident
No — 0.3mm of rain falling.
- Poor:Grass wetness
- Grass wetdew forming, raining now
- Poor:Ground firmness
- Ground soft27mm rain over the last week
- Marginal:Growth
- Growing slowlygrowth potential 0.29
- Good:Temperature
- Temperature10°C
- Good:Wind
- Wind light6 km/h
Limiting factor:grass wetness
Wednesday 9 September: Good. midday–8pm — ground soft in places — 32mm rain over the last week
Wednesday 9 September · midday–8pmReasonably confident
midday–8pm — ground soft in places — 32mm rain over the last week
- Marginal:Grass wetness
- Grass dryrain earlier today
- Marginal:Ground firmness
- Ground soft in places32mm rain over the last week
- Marginal:Growth
- Growing slowlygrowth potential 0.29
- Good:Temperature
- Temperature11°C
- Good:Wind
- Wind light17 km/h
- Sociable hours
- Fine by the neighboursstarts once the dew has burnt off
Limiting factor:ground firmness
Thursday 10 September: Not worth it. No — 0.9mm of rain falling.
Thursday 10 SeptemberReasonably confident
No — 0.9mm of rain falling.
- Poor:Grass wetness
- Grass wetraining now
- Poor:Ground firmness
- Ground soft24mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.51
- Good:Temperature
- Temperature11°C
- Good:Wind
- Wind light16 km/h
Limiting factor:grass wetness
Friday 11 September: Not worth it. No — 0.3mm of rain falling.
Friday 11 SeptemberLow confidence this far out
No — 0.3mm of rain falling.
- Poor:Grass wetness
- Grass wetrain earlier today
- Poor:Ground firmness
- Ground soft35mm rain over the last week
- Good:Growth
- Growing steadilygrowth potential 0.44
- Good:Temperature
- Temperature12°C
- Good:Wind
- Wind light14 km/h
Limiting factor:grass wetness
Saturday 12 September: Good. 1pm–8pm — grass dry — rain earlier today
Saturday 12 September · 1pm–8pmLow confidence this far out
1pm–8pm — grass dry — rain earlier today
- Marginal:Grass wetness
- Grass dryrain earlier today
- Marginal:Ground firmness
- Ground soft in places36mm rain over the last week
- Good:Growth
- Growing steadilygrowth potential 0.42
- Good:Temperature
- Temperature11°C
- Good:Wind
- Wind light15 km/h
- Sociable hours
- Fine by the neighboursstarts once the dew has burnt off
Limiting factor:grass wetness
Growth
How fast it is growing, and when it will need cutting again.
0.92Growing 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 5.5mm 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
Seeding
Soil temperature at germination depth, and when the window opens.
Soil temperature
16.9°C62°F
at 6cm — germination depth
Cooling over the next 10 days.
Seeding conditions are open — soil is 16.9°C at 6cm and holding above 9°C.
Cross-checks against an independent estimate from air temperature (16.5°C), which agrees to within 1.1°C.
Almost every UK and Irish lawn is a ryegrass and fescue mix, whether it was sown or turfed. We assume that, and use9°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 ryegrasslikely yours | 8°C | 5–10 |
| Red / chewings fescuelikely yours | 8–10°C | 10–14 |
| Tall fescue | 10–12°C | 10–14 |
| Browntop bentColonial bentgrass | 10–12°C | 14–21 |
| Smooth-stalked meadow grassKentucky bluegrass | 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.
Merthyr Tydfil, Wales in detail
Soil temperature at 6cm in Merthyr Tydfil, Wales is currently 16.9°C, and falling about 4.1°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 perennial ryegrass with fescue, which is what most lawns round here are sown with. That blend needs the soil to hold above 9°C before seed germinates reliably. Seeding conditions are open — soil is 16.9°C at 6cm and holding above 9°C.
7 of the next 10 days are good mowing days. The other 3 are held back by wet grass or soft ground. The best weekend slot right now is Sunday 10am–2pm, on the basis that ground soft in places — 35mm rain over the last week.
The next recommended window in Merthyr Tydfil opens at 2pm on Thursday 3 September, because that is when the dew has burnt off — earlier than that and you are cutting wet grass. Underfoot, the ground reads as soft after 60mm 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.