One of the first steps you take when you are getting a good idea 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.

The first opportunity to plant sweet potatos in Washington should be estimated by reviewing the USDA zone info.

Planting Calendar for Sweet Potatos

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

Since sweet potatos do not do well in cold weather you really should wait until after all chance of frost has passed before you can plant them.

The earliest that you can plant sweet potatos in Washington 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. You probably don't want to wait any later than that or else your sweet potatos may not have a chance to really do well. If you are starting your sweet potatos indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

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

Since the USDA zone info for Washington is not always accurate the actual date of last frost will vary from year to year. Half of the time in Washington you get a frost after April 15 so make sure that you are ready to cover your sweet potatos in the event of a late frost.

USDA Zone Info for Washington

Here is the info for USDA Zone 5b.

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

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Washington

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