Cosmos, MN 56228 Frost Dates
When can you plant in Cosmos, MN?
Typically, the last spring freeze lands around 05/06, roughly 251 days out. The first fall frost typically arrives around 10/02, about 147 frost-free days later.
Cosmos sits in USDA Zone 4b (-25 to -20°F average annual minimum). The dates above are NOAA's 1991-2020 normal at the nearest reporting station, a 30-year average, not a forecast.
What to do before the first frost
About 5 weeks of growing season left in Cosmos before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
Why 05/06 isn't a guarantee
05/06 is the middle of 30 years of NOAA records, not a promise. Plant by 04/23 and you're betting against frost in roughly 9 years out of 10. 05/22 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Cosmos compares
At roughly 147 frost-free days, Cosmos places 35,960 of 40,283 ZIP codes in this dataset. Within MN, it ranks 612 of 943.
Learn more
local microclimates covers what one yard in Cosmos can differ from the 56228 normal. zone vs. frost date covers why Zone 4b and Cosmos's frost date answer different questions.