One of the first steps you take when you are determining your gardening schedule is find your USDA Zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

By using the USDA zone info for Portland it's possible to figure out when you can plant sweet corn.

Planting Calendar for Sweet corn

Frost tolerance for sweet corn:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Since sweet corn do ok in moderate cold you can plant them a bit earlier in the year than other frost tender plants.

The earliest that you can plant sweet corn 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 corn and expect a good harvest is probably August. You probably don't want to wait any later than that or else your sweet corn may not have a chance to really do well. Starting your sweet corn indoors is a great way to get them started a little bit earlier.

Last Frost Date

On average all chance of frost has passed is on March 15 in Portland. You should expect an average low temperature of 15°F in the coldest months of winter.

Keep in mind that the actual date of last frost is just an average because it is based on the USDA zone info for Portland and it changes from year to year. Half of the time in Portland last frost occurs after March 15 so make sure that you are ready to cover your sweet corn if you have a surprise late frost.

USDA Zone Info for Portland

Here is the info for USDA Zone 8b.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	15°F
Highest Expected Low	20°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 20°F.

Plants to Grow in Portland

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