Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

In Johnston you can determine when to plant corn by referring to the USDA zone info.

Planting Calendar for Corn

Frost tolerance for corn:	Not tolerant of frost.
When to plant:	After the last frost has passed.

You really shouldn't plant corn until after the last frost when the weather gets warmer because they require warm weather.

The earliest that you can plant corn in Johnston is April. However, you really should wait until May if you don't want to take any chances.

The last month that you can plant corn and expect a good harvest is probably August. You probably don't want to wait any later than that or else your corn may not have a chance to grow to maturity. You can get started a couple of weeks earlier by starting your corn indoors.

Last Frost Date

On average the last frost is on April 15 in Johnston. You can expect an average low temperature of -20°F in the coldest months of winter.

Keep in mind that USDA zone info for Johnston is just an average and the actual date of last frost will vary from year to year. Since half of the time in Johnston there is a last frost after April 15 be ready to cover your corn in the event of a late frost.

USDA Zone Info for Johnston

Here is the info for USDA Zone 5a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-20°F
Highest Expected Low	-15°F

This means that on a really cold year, the coldest it will get is -20°F. On most years you should be prepared to experience lows near -15°F.

Plants to Grow in Johnston

You may be interested in your other planting guides for Johnston.