One of the first steps you take when you are estimating your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A way of determining when you can plant sweet potatos is to refer to the USDA zone info for Lewiston.

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.

Since sweet potatos require warm weather it's necessary to wait until after all chance of frost has passed before you can plant them.

The earliest that you can plant sweet potatos in Lewiston 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. If you wait any later than that and your sweet potatos may not have a chance to really do well. Starting your sweet potatos indoors is a great way to get them started a few weeks earlier.

Last Frost Date

The average date of last frost is April 15 in Lewiston. It might get as low as 5°F during the coldest months of winter.

Remember that the actual date of last frost is just an average because it is based on the USDA zone info for Lewiston and it will vary from year to year. Half of the time in Lewiston last frost occurs after April 15 so just be sure to be ready to cover your sweet potatos in the event of a surprise late frost.

USDA Zone Info for Lewiston

Here is the info for USDA Zone 7b.

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

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

Plants to Grow in Lewiston

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