Castana, IA 51010 Frost Dates
When can you plant in Castana, IA?
Typically, the last spring freeze lands around 04/25, roughly 240 days out. The first fall frost typically arrives around 10/12, about 170 frost-free days later.
Castana sits in USDA Zone 5b (-15 to -10°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 6 weeks of growing season left in Castana before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
Why 04/25 isn't a guarantee
04/25 is the middle of 30 years of NOAA records, not a promise. Plant by 04/11 and you're betting against frost in roughly 9 years out of 10. 05/07 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Castana compares
About 170 days separate Castana's last and first frost, putting it 29,268 of 40,283 ZIP codes nationally. Within IA, it ranks 326 of 1,042.
Learn more
zone vs. frost date covers why Zone 5b and Castana's frost date answer different questions. the frost range covers how to read the range around Castana's dates instead of trusting one.