One of the best tools that you have as gardeners to help us figure out your gardening schedule is the 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.

The first chance to plant sunflowers in Portland should be figured out by using the USDA zone info.

Planting Calendar for Sunflowers

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

Since sunflowers do not do well in cold weather it's necessary to wait until after the last frost when the weather gets warmer before you can plant them.

The earliest that you can plant sunflowers 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 sunflowers and expect a good harvest is probably September. If you wait any later than that and your sunflowers may not have a chance to really do well. If you are starting your sunflowers indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

On average the last frost has passed is on February 15 in Portland. You should expect an average low temperature of 25°F in the coldest months of winter.

Remember that USDA zone info for Portland may not be accurate from year to year and the actual date of last frost changes from year to year. Since half of the time in Portland you get a frost after February 15 be ready to protect your sunflowers if you have a late frost.

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.