One of the best tools that you have as gardeners to help us figure out your gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

A way of getting a good idea when it's a good idea to plant romanesco is to examine the USDA zone info for Iowa City.

Planting Calendar for Romanesco

Frost tolerance for romanesco:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Romanesco are one of those plants that can tolerate a little bit of cold weather which tells us that you can plant them earlier than plants that are more sensitive to the cold.

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

The last month that you can plant romanesco and expect a good harvest is probably September. If you wait any later than that and your romanesco may not have a chance to really do well. If you are starting your romanesco indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

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

Since the USDA zone info for Iowa City is not always accurate the actual date of last frost can change quite a bit from year to year. Half of the time in Iowa City it frosts late in the year after April 15 so make sure that you are ready to cover your romanesco in the event of a surprise 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.