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

You should be able to figure out when it's the best time to plant scarlet runner beans by referring to the USDA zone info for Zone 5a.

Planting Calendar for Scarlet Runner Beans

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

Scarlet Runner Beans do not do well in cold weather which tells us that you have to wait until it warms up after all chance of frost has passed before you can plant them.

The earliest that you can plant scarlet runner beans in Zone 5a is April. However, you really should wait until May 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. Any later than that and your scarlet runner beans may not have a chance to really do well. If you are starting your scarlet runner beans indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

The average date of last frost is April 15 in Zone 5a. In the coldest months of winter you should expect an average low temperature of -20°F.

Since the USDA zone info for Zone 5a is just an average the actual date of last frost is different every year. Half of the time in Zone 5a you get surprised by a frost after April 15 so make sure that you are prepared to cover your scarlet runner beans in the event of a late frost.

USDA Zone Info for Zone 5a

Here is the info for USDA Zone 5a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-20°F
Highest Expected Low	-15°F

This means that on a really cold year, the coldest it will get is -20°F. On most years you should be prepared to experience lows near -15°F.

Plants to Grow in Zone 5a

You may be interested in your other planting guides for Zone 5a.