Soil temperature in Baltimore, Maryland

Soil temperature

85°F29.3°C

at 6cm — germination depth

Cooling over the next 11 days.

Too warm to seed — the soil is heat-stressed. Wait for it to cool.

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.

Soil temperature at 6cm for reliable germination. Sources onthe method page.
SpeciesSoil tempDays
Perennial ryegrass8°C5–10
Red / chewings fescue8–10°C10–14
Tall fescuelikely yours10–12°C10–14
Browntop bentColonial bentgrass10–12°C14–21
Smooth-stalked meadow grassKentucky bluegrasslikely yours12–13°C14–28

Soil temperature at 6cm in Baltimore, Maryland is currently 29.3°C, and falling about 26.9°C over the next 11 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.

7 of the next 10 days are good mowing days. The best weekend slot right now is Sunday 10am–8pm, on the basis that no rain since Friday, ground firm.

The next recommended window in Baltimore opens at 8am on Wednesday 2 September, because anything earlier is the hour your neighbours will remember. Underfoot, the ground reads as firm after 56mm rain over the last week.

See the full mowing forecast for Baltimore

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 28.1°C cooling to 0.0°C

Tuesday 1 September: Not worth it. No — heat stress, 32°C.

Tuesday 1 SeptemberConfident

No — heat stress, 32°C.

Good:Grass wetness
Grass dryno rain since Friday
Good:Ground firmness
Ground firm56mm rain over the last week
Marginal:Growth
Growing slowlygrowth potential 0.32
Poor:Temperature
Heat stress29°C
Good:Wind
Wind light7 km/h

Limiting factor:temperature

Wednesday 2 September: Good. 8am–2pm — cool — 24°C

Wednesday 2 September · 8am–2pmConfident

8am–2pm — cool — 24°C

Good:Grass wetness
Grass dryno rain since Friday
Good:Ground firmness
Ground firm56mm rain over the last week
Good:Growth
Growing wellgrowth potential 0.53
Marginal:Temperature
Temperature23°C
Good:Wind
Wind light5 km/h
Sociable hours
A bit early or late, but finestarts when it stops being antisocial

Limiting factor:temperature

Thursday 3 September: Good. 8am–11am — grass dry — rain earlier today

Thursday 3 September · 8am–11amConfident

8am–11am — grass dry — rain earlier today

Good:Grass wetness
Grass dryrain earlier today
Good:Ground firmness
Ground firm57mm rain over the last week
Good:Growth
Growing steadilygrowth potential 0.40
Poor:Temperature
Temperature22°C
Good:Wind
Wind light4 km/h
Sociable hours
A bit early or late, but finestarts once the dew has burnt off

Limiting factor:grass wetness

Friday 4 September: Good. No — 6.7mm of rain falling.

Friday 4 SeptemberConfident

No — 6.7mm of rain falling.

Marginal:Grass wetness
Grass dryrain earlier today
Good:Ground firmness
Ground firm32mm rain over the last week
Good:Growth
Growing steadilygrowth potential 0.35
Poor:Temperature
Cool25°C
Good:Wind
Wind light10 km/h

Limiting factor:temperature

Saturday 5 September: Good. 8am–8pm — rain earlier today, ground firm

Saturday 5 September · 8am–8pmReasonably confident

8am–8pm — rain earlier today, ground firm

Good:Grass wetness
Grass dryrain earlier today
Good:Ground firmness
Ground firm15mm rain over the last week
Good:Growth
Growing wellgrowth potential 0.76
Marginal:Temperature
Temperature20°C
Good:Wind
Wind light12 km/h
Sociable hours
A bit early or late, but finestarts when it stops being antisocial

Limiting factor:none

Sunday 6 September: Good. 10am–8pm — no rain since Friday, ground firm

Sunday 6 September · 10am–8pmReasonably confident

10am–8pm — no rain since Friday, ground firm

Good:Grass wetness
Grass dryno rain since Friday
Good:Ground firmness
Ground firm16mm rain over the last week
Good:Growth
Growing wellgrowth potential 0.95
Good:Temperature
Temperature17°C
Good:Wind
Wind light9 km/h
Sociable hours
Fine by the neighboursstarts when it stops being antisocial

Limiting factor:none

Monday 7 September: Good. 10am–3pm — no rain since Friday, ground firm

Monday 7 September · 10am–3pmReasonably confident

10am–3pm — no rain since Friday, ground firm

Good:Grass wetness
Grass dryno rain since Friday
Good:Ground firmness
Ground firm16mm rain over the last week
Good:Growth
Growing wellgrowth potential 0.83
Marginal:Temperature
Temperature19°C
Good:Wind
Wind light2 km/h
Sociable hours
Fine by the neighboursstarts when it stops being antisocial

Limiting factor:none

Tuesday 8 September: Good. 8am–1pm — no rain since Friday, ground firm

Tuesday 8 September · 8am–1pmReasonably confident

8am–1pm — no rain since Friday, ground firm

Good:Grass wetness
Grass dryno rain since Friday
Good:Ground firmness
Ground firm16mm rain over the last week
Good:Growth
Growing wellgrowth potential 0.69
Marginal:Temperature
Temperature20°C
Good:Wind
Wind light12 km/h
Sociable hours
A bit early or late, but finestarts when it stops being antisocial

Limiting factor:temperature

Wednesday 9 September: Not worth it. No — ground frozen.

Wednesday 9 SeptemberLow confidence this far out

No — ground frozen.

Marginal:Grass wetness
Grass dryno rain since Friday
Good:Ground firmness
Ground firm16mm rain over the last week
Good:Growth
Growing wellgrowth potential 0.80
Good:Temperature
Temperature22°C
Good:Wind
Wind light5 km/h

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 drydried off since a shower 0 hours ago
Good:Ground firmness
Ground firm17mm rain over the last week
Good:Growth
Growing wellgrowth potential 0.71
Marginal:Temperature
Temperature22°C
Good:Wind
Wind light11 km/h

Limiting factor:grass wetness

Nearby

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These are town-centre figures. Yours will differ a little.

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