Marion, IA 52409 Frost Dates
When can you plant in Marion, IA?
Around 04/28 is the usual last spring frost, about 243 days away. The first fall frost typically arrives around 10/12, about 166 frost-free days later.
Zone 5a (-20 to -15°F average annual minimum) comes from the USDA Plant Hardiness Zone Map; the frost dates above are the 1991-2020 normal at the nearest reporting NOAA station for Marion, not a forecast for this year.
What to do before the first frost
About 6 weeks of growing season left in Marion before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
Why 04/28 isn't a guarantee
04/28 is the middle of 30 years of NOAA records, not a promise. Plant by 04/14 and you're betting against frost in roughly 9 years out of 10. 05/13 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Marion compares
About 166 days separate Marion's last and first frost, putting it 30,288 of 40,283 ZIP codes nationally. Within IA, it ranks 444 of 1,042.
Learn more
local microclimates covers what one yard in Marion can differ from the 52409 normal. zone vs. frost date covers why Zone 5a and Marion's frost date answer different questions.