One of the best tools that you have as gardeners to help us determine 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 possible to plant sweet corn is to examine the USDA zone info for Waterloo.

Planting Calendar for Sweet corn

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

Since sweet corn do ok in moderate cold you can plant them a bit earlier in the year than other frost tender plants.

The earliest that you can plant sweet corn in Waterloo 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 sweet corn and expect a good harvest is probably August. You probably don't want to wait any later than that or else your sweet corn may not have a chance to grow to maturity. Starting your sweet corn indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on April 15 in Waterloo. In the coldest months of winter you should expect an average low temperature of -10°F.

Remember that the actual date of last frost is just an average because it is based on the USDA zone info for Waterloo and it will vary from year to year. Since half of the time in Waterloo you get a frost after April 15 be ready to cover your sweet corn if you have a surprise late frost.

USDA Zone Info for Waterloo

Here is the info for USDA Zone 6a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-10°F
Highest Expected Low	-5°F

This means that on a really cold year, the coldest it will get is -10°F. On most years you should be prepared to experience lows near -5°F.

Plants to Grow in Waterloo

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