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When to plant · 42 states · 2027 season

When to plant onions, state by state

Twelve weeks indoors, the earliest sowing on the calendar, then transplant about four weeks before the last frost.

Spanish Onion is a long-day onion that needs 36° N or further north to bulb. The 9 states where every listed city sits south of that line are left out; grow a short-day onion there.

StateLast frost medianStart indoorsPlant out medianPlant out warm – cold tenth
AlaskaMay 18Feb 23Apr 20Apr 1 – May 4
ArkansasMar 28Jan 3Feb 28Feb 16 – Mar 12
CaliforniaFeb 7Nov 15Jan 10Dec 8 – Apr 6
ColoradoMay 7Feb 12Apr 9Apr 2 – May 9
ConnecticutApr 20Jan 26Mar 23Mar 17 – Apr 5
DelawareApr 7Jan 13Mar 10Mar 6 – Mar 14
District of ColumbiaMar 24Dec 30Feb 24Feb 24 – Mar 12
IdahoMay 14Feb 19Apr 16Mar 27 – May 12
IllinoisApr 17Jan 23Mar 20Mar 10 – Mar 30
IndianaApr 22Jan 28Mar 25Mar 14 – Mar 31
IowaApr 28Feb 3Mar 31Mar 23 – Apr 5
KansasApr 17Jan 23Mar 20Mar 11 – Mar 31
KentuckyApr 15Jan 21Mar 18Mar 6 – Mar 27
MaineMay 6Feb 11Apr 8Mar 30 – Apr 18
MarylandApr 5Jan 11Mar 8Feb 27 – Mar 25
MassachusettsApr 27Feb 2Mar 30Mar 16 – Apr 9
MichiganMay 3Feb 8Apr 5Mar 29 – Apr 25
MinnesotaMay 4Feb 9Apr 6Mar 28 – Apr 18
MissouriApr 11Jan 17Mar 14Mar 5 – Mar 22
MontanaMay 20Feb 25Apr 22Apr 11 – May 9
NebraskaApr 27Feb 2Mar 30Mar 24 – Apr 10
NevadaApr 15Jan 21Mar 18Dec 27 – May 5
New HampshireMay 8Feb 13Apr 10Apr 2 – Apr 22
New JerseyApr 15Jan 21Mar 18Mar 5 – Mar 28
New MexicoMay 2Feb 7Apr 4Mar 1 – May 1
New YorkMay 1Feb 6Apr 3Mar 5 – Apr 16
North CarolinaMar 31Jan 6Mar 3Feb 22 – Mar 22
North DakotaMay 12Feb 17Apr 14Apr 8 – Apr 21
OhioApr 24Jan 30Mar 27Mar 20 – Apr 3
OklahomaApr 4Jan 10Mar 7Feb 28 – Mar 15
OregonApr 11Jan 17Mar 14Feb 9 – Apr 29
PennsylvaniaApr 27Feb 2Mar 30Mar 17 – Apr 12
Rhode IslandApr 11Jan 17Mar 14Mar 14 – Apr 3
South DakotaMay 6Feb 11Apr 8Apr 3 – Apr 16
TennesseeApr 6Jan 12Mar 9Feb 28 – Mar 23
UtahMay 5Feb 10Apr 7Mar 12 – May 4
VermontMay 13Feb 18Apr 15Apr 3 – Apr 23
VirginiaApr 11Jan 17Mar 14Mar 2 – Mar 29
WashingtonApr 14Jan 20Mar 17Feb 8 – Apr 15
West VirginiaApr 23Jan 29Mar 26Mar 11 – Apr 6
WisconsinMay 4Feb 9Apr 6Mar 29 – Apr 21
WyomingMay 21Feb 26Apr 23Apr 13 – May 5

Each state's dates are the ZIP-weighted median of NOAA NCEI 1991–2020 station normals, scheduled for Spanish Onion by the same engine as the Plan Builder. The last column is the spread between the warmest and coldest tenth of the state's ZIP codes. Open a state for every city and cultivar.

Spanish Onion grow guide →Every crop →Frost dates by city →