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.

A common way of determining when it's the best time to plant scarlet runner beans is to check out the USDA zone info for Zone 4b.

Planting Calendar for Scarlet Runner Beans

Frost tolerance for scarlet runner beans:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

You can not plant scarlet runner beans until after the last frost has passed because they do not do well in cold weather.

The earliest that you can plant scarlet runner beans in Zone 4b is May. However, you really should wait until June 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 August. You probably don't want to wait any later than that or else your scarlet runner beans may not have a chance to fully mature. Starting your scarlet runner beans indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

On average the last frost has passed is on May 15 in Zone 4b. It might get as low as -25°F during the coldest months of winter.

Since the USDA zone info for Zone 4b is just an average the actual date of last frost can change quite a bit from year to year. Half of the time in Zone 4b there is a last frost after May 15 so be sure to be ready to protect your scarlet runner beans if you have a surprise late frost.

USDA Zone Info for Zone 4b

Here is the info for USDA Zone 4b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-25°F
Highest Expected Low	-20°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 -20°F.

Plants to Grow in Zone 4b

You may be interested in your other planting guides for Zone 4b.