Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The first opportunity to plant scarlet runner beans in Mercer Island can be figured out by using the USDA zone info.

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.

It's probably not a good idea to plant scarlet runner beans until after the last frost has passed because they are not cold tolerant.

The earliest that you can plant scarlet runner beans in Mercer Island 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. You can get started a couple of weeks earlier by starting your scarlet runner beans indoors.

Last Frost Date

On average the last frost when the weather gets warmer is on March 15 in Mercer Island. It might get as low as 15°F during the coldest months of winter.

Since the USDA zone info for Mercer Island may not be accurate from year to year the actual date of last frost can change quite a bit from year to year. Half of the time in Mercer Island there is a last frost after March 15 so just be sure to be ready to cover your scarlet runner beans if you have one of those late frosts.

USDA Zone Info for Mercer Island

Here is the info for USDA Zone 8b.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	15°F
Highest Expected Low	20°F

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

Plants to Grow in Mercer Island

You may be interested in your other planting guides for Mercer Island.