When to Plant Bunching Onions in Iowa City, IA

The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

By referring to the USDA zone info for Iowa City it's a good idea to estimate when you can plant bunching onions.

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Planting Calendar for Bunching Onions

Frost tolerance for bunching onions: Tolerant of a very small amount of frost.
When to plant: Up to 3 weeks before last frost.

Since bunching onions are one of those plants that can tolerate a tiny bit of cold weather you can plant them slightly earlier in the year than plants that are more sensitive to the cold.

JanFebMarAprMayJunJulAugSepOctNovDec
Legend 
A good time to plant bunching onions
Possibly ok, but a risky time to plant bunching onions
Probably not a good time to plant bunching onions

The earliest that you can plant bunching onions in Iowa City is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant bunching onions and expect a good harvest is probably August. If you wait any later than that and your bunching onions may not have a chance to really do well. Starting your bunching onions indoors is a great way to get them started a little bit earlier.

Last Frost Date

On average the last frost is on April 15 in Iowa City. You can expect an average low temperature of -15°F in the coldest months of winter.

Always keep in mind that USDA zone info for Iowa City may not be accurate from year to year and the actual date of last frost changes from year to year. Half of the time in Iowa City you get a frost after April 15 so just be sure to be ready to protect your bunching onions in the event of a late frost.

USDA Zone Info for Iowa City

Here is the info for USDA Zone 5b.

Average Date of Last Frost (spring)April 15
Average Date of First Frost (fall)October 15
Lowest Expected Low-15°F
Highest Expected Low-10°F

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Iowa City

You may be interested in your other planting guides for Iowa City.