One of the first steps you take when you are making a decision about 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.

One way of figuring out when to plant sweet potatos is to consult the USDA zone info for Portland.

Planting Calendar for Sweet Potatos

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

Sweet Potatos require warm weather which means that you have to wait until it warms up after the last frost when the weather gets warmer before you can plant them.

The earliest that you can plant sweet potatos in Portland 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 potatos and expect a good harvest is probably September. Any later than that and your sweet potatos may not have a chance to really do well. You can get started a little bit earlier by starting your sweet potatos indoors.

Last Frost Date

The average date of last frost is February 15 in Portland. It might get as low as 25°F during the coldest months of winter.

Since the USDA zone info for Portland may not be accurate from year to year the actual date of last frost can change quite a bit from year to year. Since half of the time in Portland you get surprised by a frost after February 15 be ready to protect your sweet potatos in the event of one of those late frosts.

USDA Zone Info for Portland

Here is the info for USDA Zone 9b.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	25°F
Highest Expected Low	30°F

This means that on a really cold year, the coldest it will get is 25°F. On most years you should be prepared to experience lows near 30°F.

Plants to Grow in Portland

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