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.

In Zone 4b you can determine when it's a good idea to plant runner beans by reviewing the USDA zone info.

Planting Calendar for Runner beans

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

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

The earliest that you can plant 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 runner beans and expect a good harvest is probably August. Any later than that and your runner beans may not have a chance to fully mature. Starting your runner beans indoors is a great way to get them started a little bit earlier.

Last Frost Date

In Zone 4b the average date of last frost happens on May 15. You can expect an average low temperature of -25°F in the coldest months of winter.

Just be sure to remember that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Zone 4b and it changes from year to year. Half of the time in Zone 4b you get surprised by a frost after May 15 so make sure that you are ready to protect your runner beans if you have one of those late frosts.

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.