Use this planting calendar to find the best times of the year to grow fruits, vegetables, herbs, flowers, and other popular plants in Grinnell, IA, based on the USDA Hardiness Zone 5b.
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Grinnell, IA Frost Dates & Growing Season
Last Spring Frost Date for Grinnell, IA
The average last frost date in spring for Grinnell is May 1st. For gardeners planting sensitive crops like tomatoes, peppers, and basil, it is generally recommended to wait until May 15th before moving plants outdoors. Waiting these extra few weeks significantly reduces the risk of a late freeze damaging young transplants.
First Fall Frost Date for Grinnell, IA
The average first frost date in fall for Grinnell is October 10th. This date marks the approximate end of the growing season for tender plants. Gardeners should plan to harvest frost-sensitive vegetables or provide heavy protection (such as row covers) before this date to avoid crop loss.
Growing Season Length in Grinnell, IA
Based on historical frost data, the estimated growing season length in Grinnell is approximately 162 days. This duration determines which vegetable varieties have enough time to reach maturity before the winter cold sets in. Short-season varieties are recommended for crops that require a longer warm period.
Please note: These dates are climatological averages. Actual weather conditions vary by year. Always check the local 10-day forecast before planting.
Grinnell, IA Planting Calendar
This weekly planting calendar displays the ideal windows for starting seeds, transplanting, and harvesting your plants.
Grinnell, IA Monthly Planting Recommendations
February
In February, recommended activities include starting Impatiens seeds indoors (from February 20th to March 6th), starting Geranium seeds indoors (from February 20th to March 6th), and starting Leek seeds indoors (from February 20th to March 6th).
March
In March, recommended activities include starting Broccoli seeds indoors (from March 6th to March 20th), starting Tomatillo seeds indoors (from March 6th to March 20th), and starting Aubergine seeds indoors (from March 6th to March 20th).
April
In April, recommended activities include direct sowing Alfalfa (from April 3rd to April 17th), starting Cantaloupe seeds indoors (from April 3rd to April 17th), and direct sowing German Chamomile (from April 17th to May 1st).
May
In May, recommended activities include direct sowing Fenugreek (from May 1st to May 15th), direct sowing Moss Rose (from May 8th to May 22nd), and direct sowing Black Bean (from May 15th to May 29th).