Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. 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 determine when you can plant blue throatwort by reviewing the USDA zone info for Mercer Island.

Planting Calendar for Blue Throatwort

Frost tolerance for blue throatwort:	Not tolerant of frost.
When to plant:	After the last frost.

Since blue throatwort do not do well in cold weather you need to wait until after the last frost when the weather gets warmer before you can plant them.

The earliest that you can plant blue throatwort 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 blue throatwort and expect a good harvest is probably August. Any later than that and your blue throatwort may not have a chance to grow to maturity. You can get started a couple of weeks earlier by starting your blue throatwort indoors.

Last Frost Date

The average date of last frost is March 15 in Mercer Island. You should expect an average low temperature of 15°F in the coldest months of winter.

Just be sure to remember that USDA zone info for Mercer Island may not be accurate from year to year and the actual date of last frost changes from year to year. Half of the time in Mercer Island there is a last frost after March 15 so make sure that you are prepared to protect your blue throatwort in the event of a late frost.

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.