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.

A way of figuring out when you can plant sweet potatos is to refer to the USDA zone info for Johnston.

Planting Calendar for Sweet Potatos

Frost tolerance for sweet potatos:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

You should not plant sweet potatos until after all chance of frost has passed because they do not do well in cold weather.

The earliest that you can plant sweet potatos 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 sweet potatos and expect a good harvest is probably August. Any later than that and your sweet potatos may not have a chance to fully mature. If you are starting your sweet potatos indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

In Johnston the average date of last frost happens on April 15. In the coldest months of winter you should expect an average low temperature of -20°F.

Keep in mind that USDA zone info for Johnston is just an average and the actual date of last frost is different every year. Since half of the time in Johnston you get a frost after April 15 be ready to protect your sweet potatos in the event of a surprise 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.