What to do in Castle Rock now
Castle Rock is in cool-season grass country. Dates are typical for this spot, worked out from 23 years of weather at Denver Centennial Ap; each status uses this year's soil estimates.
Cool-season: tall fescue, Kentucky bluegrass, perennial ryegrass, fine fescue
- Crabgrass pre-emergent Closed Mar 24 Typical: Apr 13 – May 112-inch soil held 55°F for a week from Mar 24, so crabgrass was sprouting. Next window: about Apr 13 – May 11, 2027.
- Seed or overseed Late · risky Typical: Sep 11 – Oct 16Soil fell below 55°F on Oct 31. Seed sown now germinates slowly and may not survive winter. The hard stop, 4-inch soil under 50°F, typically comes around Oct 30.
- Late-fall feeding Final feeding due now Typical: Oct 30 – Nov 28Not too late. Feed on your normal fall schedule; the last feeding of the year goes down when 4-inch soil falls to about 50°F (typically Oct 30) and before it reaches 40°F (typically Nov 28).
Warm-season: bermudagrass, zoysia, St. Augustine, centipede, bahia
- Crabgrass pre-emergent Closed Mar 24 Typical: Apr 13 – May 112-inch soil held 55°F for a week from Mar 24, so crabgrass was sprouting. Next window: about Apr 13 – May 11, 2027.
- Seed or sod Wait for late spring Typical: Jun 8 – Sep 11Warm-season seed needs 4-inch soil at 65°F or more, and seedlings need the rest of summer to establish. Next window opens about Jun 8.
- Fall pre-emergent (Poa annua) Germinating since Sep 22 Typical: By Sep 104-inch soil fell below 70°F on Sep 22, when annual bluegrass begins to sprout. A pre-emergent now only stops later flushes; plan to apply by about Sep 10 next year.
- Dormancy and last feeding Dormant since about Oct 31 Typical: Around Oct 164-inch soil has stayed under 55°F since Oct 31, so warm-season grass is going brown. It is too late to fertilize; feed again after spring green-up, once soil holds 65°F (typically Jun 8).
The last 60 days and the week ahead
Castle Rock soil is 3° warmer than normal for Nov 3, warmer than on 74% of those dates since 2005, and 3° warmer than a year ago.
The green line is our estimate of the daily average soil temperature 2 inches down, driven by temperatures at Denver Centennial Ap, 20.4 km from the city center. The dashed part runs the National Weather Service forecast through the same model. Hover or tap for any day.
2-inch soil, estimated From the NWS forecast Normal Normal range (8 years in 10)
Show the numbers
| Date | 2-inch soil | 4-inch soil | Air high / low | Normal (2 in) |
|---|---|---|---|---|
| Oct 20 | 55° | 57° | 68° / 45° | 52° |
| Oct 21 | 56° | 58° | 75° / 43° | 51° |
| Oct 22 | 59° | 60° | 73° / 56° | 51° |
| Oct 23 | 61° | 62° | 74° / 59° | 51° |
| Oct 24 | 58° | 59° | 59° / 39° | 50° |
| Oct 25 | 54° | 56° | 55° / 38° | 49° |
| Oct 26 | 53° | 55° | 59° / 40° | 49° |
| Oct 27 | 53° | 55° | 66° / 39° | 48° |
| Oct 28 | 53° | 55° | 67° / 40° | 47° |
| Oct 29 | 52° | 54° | 67° / 34° | 47° |
| Oct 30 | 53° | 54° | 68° / 40° | 46° |
| Oct 31 | 52° | 54° | 59° / 44° | 46° |
| Nov 1 | 52° | 54° | 63° / 43° | 46° |
| Nov 2 | 51° | 53° | 55° / 42° | 46° |
| Nov 3 | 49° | 51° | 53° / 37° | 46° |
| Nov 4 (forecast) | 48° | 50° | 55° / 34° | 46° |
| Nov 5 (forecast) | 47° | 49° | 56° / 35° | 47° |
| Nov 6 (forecast) | 46° | 48° | 55° / 33° | 46° |
| Nov 7 (forecast) | 46° | 48° | 57° / 34° | 46° |
| Nov 8 (forecast) | 48° | 49° | 66° / 38° | 46° |
| Nov 9 (forecast) | 49° | 50° | 65° / 39° | 45° |
Which grass grows in Castle Rock
Castle Rock winters are cold enough (January averages 32°F) that cool-season grasses, mostly Kentucky bluegrass, tall fescue and perennial ryegrass, make up most lawns. They grow in spring and fall and slow down in summer heat.
Castle Rock soil through the year
Weekly 2-inch estimates for 2026 so far against 2025 and the normal for each week. The red lines mark 50°F, when crabgrass pre-emergent should be down, and 65°F, when warm-season seed sprouts well.
2026 2025 Normal (2005–2025) 8 years in 10
Normal by month
| Month | 2 in | 4 in | Air |
|---|---|---|---|
| Jan | 35° | 36° | 32° |
| Feb | 36° | 37° | 33° |
| Mar | 41° | 42° | 41° |
| Apr | 47° | 48° | 47° |
| May | 56° | 57° | 56° |
| Jun | 68° | 70° | 67° |
| Jul | 75° | 77° | 73° |
| Aug | 73° | 75° | 71° |
| Sep | 66° | 68° | 63° |
| Oct | 53° | 55° | 50° |
| Nov | 43° | 44° | 39° |
| Dec | 36° | 37° | 31° |
Soil: average of our daily estimates, 2005–2025. Air: NOAA 1991–2020 normals for the station.
Typical lawn dates in Castle Rock
Each date is when the soil estimate (or the air, for freezes) crossed the threshold, year by year since 2005. “Early” and “late” are the 10th and 90th percentile years, so 8 years in 10 fall between them.
| Event | Typical | 2026 |
|---|---|---|
| Last spring freeze (32°F) | May 9 | May 6 |
| Crabgrass model: 250 growing degree days | Mar 3 | Feb 7 |
| Pre-emergent window opens (2-inch soil 50°F) | Apr 13 | Mar 21 |
| Crabgrass begins to sprout (2-inch soil 55°F) | May 11 | Mar 24 |
| Cool-season lawns start growing (4-inch soil 55°F) | May 10 | Mar 24 |
| Warm-season seeding opens (4-inch soil 65°F) | Jun 8 | Jun 3 |
| Cool-season seeding opens (4-inch soil under 70°F) | Sep 11 | Sep 23 |
| Cool-season seeding ends (4-inch soil under 55°F) | Oct 16 | Oct 31 |
| Warm-season grass goes dormant (4-inch under 55°F) | Oct 16 | Oct 31 |
| First fall freeze (32°F) | Oct 9 | Oct 16 |
| Roots stop feeding (4-inch soil under 40°F) | Nov 28 | not yet |
Where these numbers come from
There is no soil sensor in most cities, so we estimate it. Shallow soil follows air temperature with a lag of a few days, and runs a little warmer than the air in fall. We fitted that relationship to 190 USDA soil-sensor stations; on years held out of the fit, the estimate was off by 3.3°F on an average day, and it put the spring 55°F date within a median of 3 days. Read the methodology.
Weather: RCC ACIS station KAPA (DENVER CENTENNIAL AP), daily data since 1998. Forecast: National Weather Service, BOU office, issued Nov 4, 2026, 1:46 AM EST. Last observed day: Nov 3, 2026.
Castle Rock questions
What is the soil temperature in Castle Rock today? Our estimate for Nov 3 is 49°F at 2 inches and 51°F at 4 inches, as a daily average. Early-morning soil runs a few degrees cooler than that, and afternoon soil warmer.
When should I put down crabgrass pre-emergent in Castle Rock? Apply when 2-inch soil holds about 50°F and before it holds 55°F. That has typically been Apr 13 to May 11 in Castle Rock. For 2026 the window closed on Mar 24.
Is it too late to overseed in Castle Rock? Late · risky. Soil fell below 55°F on Oct 31. Seed sown now germinates slowly and may not survive winter. The hard stop, 4-inch soil under 50°F, typically comes around Oct 30.
Is it too late to fertilize in Castle Rock? Final feeding due now. Not too late. Feed on your normal fall schedule; the last feeding of the year goes down when 4-inch soil falls to about 50°F (typically Oct 30) and before it reaches 40°F (typically Nov 28).
When is the last frost in Castle Rock? The last 32°F night of spring has typically come around May 9, and as late as May 20 in 1 year in 10. The first fall freeze typically arrives around Oct 9.
Why 2 inches and 4 inches? Crabgrass and most weed seeds sprout in the top inch or two, so pre-emergent timing follows 2-inch soil. Grass seed and roots respond to the slightly steadier soil at about 4 inches.
How accurate is this? It is a model, not a probe in your yard. Expect about 3–4°F of difference on a given day; shade, slope, mulch and irrigation all move real soil. The dates and trends are more reliable than any single day.