Iowa planting calendar

When to put transplants or seed in the ground across Iowa, worked out from the average last spring and first fall frost for each USDA zone in the state, and what to line up before you commit ground. Written for farms that sell what they grow.

Your zone in Iowa: frost dates

Zones 4b–5b run through Iowa. Frost dates are long-term averages for planning, not a forecast for your field.

  • Zone 4b
    Mason City and the northern tier
    Last frost
    ~May 15
    First frost
    ~September 22
    Frost-free days
    130
    Winter low
    -25°F to -20°F
  • Zone 5a
    Des Moines, Cedar Rapids and central Iowa
    Last frost
    ~May 8
    First frost
    ~September 29
    Frost-free days
    144
    Winter low
    -20°F to -15°F
  • Zone 5b
    Council Bluffs and the Missouri River valley
    Last frost
    ~May 1
    First frost
    ~October 6
    Frost-free days
    158
    Winter low
    -15°F to -10°F

What it costs to grow an acre in Iowa

No published Iowa budget is transcribed here yet, so this page shows planting dates only — we do not publish cost figures we cannot source. Neighboring state budgets from NC State, UGA and UF/IFAS are on the crop profitability page.

Every figure is transcribed from a published land-grant enterprise budget for that state. These are planning budgets built from grower panels and dealer quotes, not surveys of what farms actually spent — your invoices override them everywhere they exist.

When to plant Iowa's main crops

Calculated for Zone 5a (Des Moines and central Iowa). Pick your own zone on the crop page.

  • Tomatoes
    May 15 – June 5
    August 5 – September 2
  • Peppers
    May 22 – June 12
    August 7 – September 4
  • Sweet corn
    May 8 – May 29
    July 29 – August 26
  • Cucumbers
    May 15 – June 5
    July 16 – August 13
  • Summer squash
    May 15 – June 5
    July 11 – August 8
  • Green beans (bush)
    May 8 – May 29
    July 9 – August 6
  • Cabbage
    April 10 – May 1
    July 1 – July 29
  • Broccoli
    April 10 – May 1
    June 21 – July 19
  • Carrots
    April 10 – May 1
    June 26 – July 24
  • Lettuce
    April 3 – April 24
    May 25 – June 22
  • Strawberries
    October 16 – November 6
    April 21 – May 19
  • Watermelon
    May 22 – June 12
    August 22 – September 19

What zone is my farm?

  • Mason CityZone 4b
  • Des MoinesZone 5a
  • Cedar RapidsZone 5a
  • Council BluffsZone 5b

If your farm sits in a zone that is not listed here, start from the calendar index and pick the closest match, then confirm with your county extension office.

Before you commit ground

A planting date tells you when a crop can grow — not whether it pays. Work out your breakeven price, then line up who is buying before you plant.

Iowa planting and cost questions

What USDA planting zone is Mason City, Iowa?
The calendar carries Mason City in Zone 4b. Average last spring frost is around May 15 and average first fall frost around September 22, which is about 130 frost-free days.
What USDA planting zone is Des Moines, Iowa?
The calendar carries Des Moines in Zone 5a. Average last spring frost is around May 8 and average first fall frost around September 29, which is about 144 frost-free days.
When should I plant tomatoes in Iowa?
In Zone 5a (Des Moines and central Iowa), May 15 – June 5 august 5 – september 2

Other state pages

Dates are calculated from average first and last frost dates for each zone. Your microclimate, elevation and soil temperature can shift any window by a week or more — treat these as starting points and keep your own records.