One of the best tools that you have as gardeners to help us estimate your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

It's possible to figure out when it's a good idea to plant scarlet runner beans by referring to the USDA zone info for Portland.

Planting Calendar for Scarlet Runner Beans

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

Scarlet Runner Beans are not cold tolerant which tells us that it is necessary to wait until it warms up after the last frost has passed before you can plant them.

The earliest that you can plant scarlet runner beans 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 scarlet runner beans and expect a good harvest is probably September. If you wait any later than that and your scarlet runner beans may not have a chance to grow to maturity. If you are starting your scarlet runner beans indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

In Portland the average date of last frost happens on February 15. In the coldest months of winter you can expect an average low temperature of 25°F.

Always keep in mind that the actual date of last frost is not always accurate because it is based on the USDA zone info for Portland and it will vary from year to year. Since half of the time in Portland it frosts late in the year after February 15 be ready to protect your scarlet runner beans in the event of a surprise 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.