Ironwood, MI 54547 Frost Dates
When can you plant in Ironwood, MI?
Around 05/25 is the usual last spring frost, about 270 days away. The first fall frost typically arrives around 09/21, about 117 frost-free days later.
The USDA Plant Hardiness Zone Map puts Ironwood in Zone 4a (-30 to -25°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
What to do before the first frost
About 3 weeks of growing season left in Ironwood before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
How much risk comes with planting early here
05/25 is the middle of 30 years of NOAA records, not a promise. Plant by 05/08 and you're betting against frost in roughly 9 years out of 10. 06/09 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Ironwood compares
Ironwood's growing season runs about 117 days, ranking 39,244 of 40,283 US ZIP codes measured here, longest to shortest. Within MI, it ranks 1,114 of 1,153.
Learn more
the frost range covers how to read the range around Ironwood's dates instead of trusting one. local microclimates covers what one yard in Ironwood can differ from the 54547 normal.