When to plant basil in Colorado

Basil
Plant out in Denver
May 11–May 25

Across Colorado the window opens between April 21 and May 17. Find your city below; the dates follow each town's own average last frost.

Start indoors, Denver
Mar 23–Apr 6
Plant out, Denver
May 11–May 25
Sow outdoors, Denver
May 11–May 25
Last sowing for a harvest
Jul 11
Last frost, Denver
May 4

Start seeds indoors 4–6 weeks before the last frost; plant out 1–3 weeks after the last frost; sow outdoors 1–3 weeks after the last frost. Basil blackens below 50°F. Wait a week or two after the last frost.

Basil planting dates by city

Start indoorsPlant outSow outdoorsFall plantingAverage last and first frost
JanFebMarAprMayJunJulAugSepOctNovDec
DenverMay 11–May 25
Colorado SpringsMay 10–May 24
AuroraMay 14–May 28
Fort CollinsMay 9–May 23
LakewoodMay 10–May 24
ThorntonMay 9–May 23
ArvadaMay 12–May 26
WestminsterMay 9–May 23
GreeleyMay 9–May 23
PuebloMay 7–May 21
CentennialMay 12–May 26
BoulderMay 13–May 27
LongmontMay 14–May 28
LovelandMay 17–May 31
BroomfieldMay 9–May 23
Commerce CityMay 10–May 24
Grand JunctionApr 21–May 5
LittletonMay 9–May 23
BrightonMay 10–May 24
WindsorMay 10–May 24
ErieMay 14–May 28
NorthglennMay 9–May 23
Security-WidefieldMay 10–May 24
EnglewoodMay 9–May 23
Pueblo WestMay 3–May 17
Wheat RidgeMay 12–May 26
LafayetteMay 9–May 23
FountainMay 10–May 24
EvansMay 9–May 23
JohnstownMay 17–May 31
All 34 cities
CityStart indoorsPlant outSow outdoorsLast frost
DenverMar 23 to Apr 6May 11 to May 25May 11 to May 25May 4
Colorado SpringsMar 22 to Apr 5May 10 to May 24May 10 to May 24May 3
AuroraMar 26 to Apr 9May 14 to May 28May 14 to May 28May 7
Fort CollinsMar 21 to Apr 4May 9 to May 23May 9 to May 23May 2
LakewoodMar 22 to Apr 5May 10 to May 24May 10 to May 24May 3
ThorntonMar 21 to Apr 4May 9 to May 23May 9 to May 23May 2
ArvadaMar 24 to Apr 7May 12 to May 26May 12 to May 26May 5
WestminsterMar 21 to Apr 4May 9 to May 23May 9 to May 23May 2
GreeleyMar 21 to Apr 4May 9 to May 23May 9 to May 23May 2
PuebloMar 19 to Apr 2May 7 to May 21May 7 to May 21Apr 30
CentennialMar 24 to Apr 7May 12 to May 26May 12 to May 26May 5
BoulderMar 25 to Apr 8May 13 to May 27May 13 to May 27May 6
LongmontMar 26 to Apr 9May 14 to May 28May 14 to May 28May 7
LovelandMar 29 to Apr 12May 17 to May 31May 17 to May 31May 10
BroomfieldMar 21 to Apr 4May 9 to May 23May 9 to May 23May 2
Commerce CityMar 22 to Apr 5May 10 to May 24May 10 to May 24May 3
Grand JunctionMar 3 to Mar 17Apr 21 to May 5Apr 21 to May 5Apr 14
LittletonMar 21 to Apr 4May 9 to May 23May 9 to May 23May 2
BrightonMar 22 to Apr 5May 10 to May 24May 10 to May 24May 3
WindsorMar 22 to Apr 5May 10 to May 24May 10 to May 24May 3
ErieMar 26 to Apr 9May 14 to May 28May 14 to May 28May 7
NorthglennMar 21 to Apr 4May 9 to May 23May 9 to May 23May 2
Security-WidefieldMar 22 to Apr 5May 10 to May 24May 10 to May 24May 3
EnglewoodMar 21 to Apr 4May 9 to May 23May 9 to May 23May 2
Pueblo WestMar 15 to Mar 29May 3 to May 17May 3 to May 17Apr 26
Wheat RidgeMar 24 to Apr 7May 12 to May 26May 12 to May 26May 5
LafayetteMar 21 to Apr 4May 9 to May 23May 9 to May 23May 2
FountainMar 22 to Apr 5May 10 to May 24May 10 to May 24May 3
EvansMar 21 to Apr 4May 9 to May 23May 9 to May 23May 2
JohnstownMar 29 to Apr 12May 17 to May 31May 17 to May 31May 10
Four Square MileMar 26 to Apr 9May 14 to May 28May 14 to May 28May 7
MontroseMar 17 to Mar 31May 5 to May 19May 5 to May 19Apr 28
LouisvilleMar 25 to Apr 8May 13 to May 27May 13 to May 27May 6
FirestoneMar 26 to Apr 9May 14 to May 28May 14 to May 28May 7

Questions

When should I plant basil in Colorado?

In Denver, plant out from May 11 to May 25. Across Colorado the window opens between April 21 and May 17, depending on the local last frost.

How is this date worked out?

Start seeds indoors 4–6 weeks before the last frost; plant out 1–3 weeks after the last frost; sow outdoors 1–3 weeks after the last frost. Frost dates are NOAA 1991–2020 averages for the weather station nearest each city.

More for Colorado

Basil in other states

Frost dates for every city in Colorado