The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The USDA zone info for South Sioux City can be looked at to estimate when it's the best time to plant sunflowers.

Planting Calendar for Sunflowers

Frost tolerance for sunflowers:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

Since sunflowers require warm weather you must wait until after the last frost before you can plant them.

The earliest that you can plant sunflowers in South Sioux City 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 sunflowers and expect a good harvest is probably August. Any later than that and your sunflowers may not have a chance to grow to maturity. If you are starting your sunflowers indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

In South Sioux City the average date of last frost happens on April 15. You should expect an average low temperature of -20°F in the coldest months of winter.

Since the USDA zone info for South Sioux City may not be accurate from year to year the actual date of last frost is different every year. Half of the time in South Sioux City you get a frost after April 15 so just be sure to be ready to cover your sunflowers in the event of one of those late frosts.

USDA Zone Info for South Sioux City

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 South Sioux City

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