Last spring freeze
Apr 30
median (50%)
8 in 10 years Apr 15 – May 13
Only a 1-in-10 chance of a freeze after May 13.
Denver, CO · NOAA frost dates
Denver frost dates & planting calendar
Last spring freeze ~Apr 30, first fall freeze ~Oct 12: a median of 165 frost-free days. The calendar below is already set to Denver (ZIP 80202). Type your own ZIP for the station nearest you.
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Denver, CO · ZIP 80202 · try yours
Denver CO area
Last spring frost
~Apr 30
safer: May 13
First fall frost
~Oct 12
safer: Sep 28
Growing season
165
frost-free days
- Start indoors
- Sow outside
- Transplant
- Fall planting
- Harvest
Median dates from NOAA 1991–2020 climate normals. Averages, not forecasts. How it works
NOAA 1991–2020 climate normals
Denver frost dates at a glance
32°F freeze dates for the Denver Water Dept, CO weather station, 3 km from ZIP 80202, 1594 m up.
First fall freeze
Oct 12
median (50%)
8 in 10 years Sep 28 – Oct 26
Only a 1-in-10 chance of a freeze before Sep 28.
Growing season
165
median frost-free days
USDA zone 6a
Station: Denver Water Dept, CO
Long-term averages, not a forecast. Your yard can run one to three weeks off these dates, so check the 10-day forecast before planting out.
Source: NOAA National Centers for Environmental Information (NCEI), U.S. Climate Normals 1991–2020 (32°F freeze probabilities: 10%, 50%, 90%). Public domain. How we use it
Planting dates for Denver
When to plant in Denver
Worked out from the median frost dates (and, for warm-season crops, NOAA’s normal night lows) with the same crop rules as the calendar below. Tap any crop there for its dates.
-
Tomatoes
- Start indoors
- Mar 25 – Apr 8
- Transplant out
- May 27 – Jun 17
Frost alone would allow transplanting from May 7, but the normal night low here only reaches 50°F (10°C) about May 27, so they go out then, started indoors 9 weeks before. Transplant when nights stay above 50°F (10°C).
-
Peppers
- Start indoors
- Mar 4 – Mar 18
- Transplant out
- May 27 – Jun 10
Frost alone would allow transplanting from May 14, but the normal night low here only reaches 50°F (10°C) about May 27, so they go out then, started indoors 12 weeks before. Loves warm soil, 65°F+ (18°C+).
-
Peas
- Sow outside
- Mar 19 – Apr 9
- Fall sowing
- Aug 3 – Aug 17
3–6 weeks before the last frost, and again 8–10 weeks before the first fall frost. Sow as soon as soil can be worked (40°F/4°C+).
-
Lettuce
- Sow outside
- Apr 2 – May 14
- Fall sowing
- Aug 17 – Sep 14
From 4 weeks before to 2 weeks after the last frost, and 4–8 weeks before the first fall frost. Bolts in heat; sow small batches often.
-
Garlic
- Plant cloves
- Sep 28 – Nov 2
- Harvest
- Jul 2 – Jul 23, next year
2 weeks before to 3 weeks after the first fall frost. Plant cloves in fall; harvest next summer when lower leaves brown.
This week
Right now in your garden
Full year
Your planting calendar
- Start indoors
- Sow outside
- Transplant
- Fall sowing / planting
- Harvest
- Harvest the season after planting
- Est. frost date
No crops match. Try another search, or clear “My picks”.
Tap ☆ to add a crop to your picks. Tap a crop name for exact dates and growing notes. Your picks and location are saved on this device.
Straight answers
Frost questions
When is the last frost in Denver?
The median last spring freeze (32°F) at NOAA’s Denver Water Dept, CO station is Apr 30, based on 1991–2020 climate normals. In 8 of 10 years it falls between Apr 15 and May 13, and there is only a 1-in-10 chance of a freeze after May 13.
When is the first fall frost in Denver?
The median first fall freeze (32°F) is Oct 12. In 8 of 10 years it falls between Sep 28 and Oct 26, and there is only a 1-in-10 chance of a freeze before Sep 28. That leaves a median of 165 frost-free days.
When should I plant tomatoes in Denver?
Using FrostLine’s crop rules with the median last frost of Apr 30 and NOAA’s normal night lows: start tomato seeds indoors Mar 25 – Apr 8 and transplant them outside May 27 – Jun 17. Frost alone would allow May 7, but nights here only average 50°F (10°C) from about May 27.
Are these dates a forecast?
No. They are long-term averages, not a forecast for this year. Your own garden can differ by one to three weeks with elevation, slope, wind and how built-up it is. Check the 10-day forecast before setting out tender plants, and enter your own ZIP for the nearest station.
How it works: each ZIP is matched to the nearest NOAA station with freeze records. More on our method.
Frost dates by city
More frost dates by city
Each page opens the same free calendar, set to that city. Or start from the home page.
- IL · zone 6b Chicago Last frost ~Apr 10First frost ~Nov 5 209 frost-free days
- WA · zone 9a Seattle Last frost ~Mar 13First frost ~Nov 17 249 frost-free days
- GA · zone 8a Atlanta Last frost ~Mar 24First frost ~Nov 8 229 frost-free days
- TX · zone 8a Dallas Last frost ~Mar 2First frost ~Nov 29 272 frost-free days
- MN · zone 4b Minneapolis Last frost ~Apr 23First frost ~Oct 16 176 frost-free days
- OR · zone 8b Portland Last frost ~Feb 25First frost ~Dec 1 279 frost-free days
- MA · zone 7a Boston Last frost ~Apr 4First frost ~Nov 9 219 frost-free days
- TN · zone 7a Nashville Last frost ~Apr 1First frost ~Oct 31 213 frost-free days
- UT · zone 7a Salt Lake City Last frost ~Mar 31First frost ~Nov 8 222 frost-free days