The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A way of estimating when it's a good idea to plant bishop's weed is to examine the USDA zone info for Duluth.

Planting Calendar for Bishop's Weed

Frost tolerance for bishop's weed:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Bishop's Weed do ok in pretty solid cold which tells us that you can plant them earlier in the year than more sensitive plants.

The earliest that you can plant bishop's weed in Duluth is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant bishop's weed and expect a good harvest is probably August. You probably don't want to wait any later than that or else your bishop's weed may not have a chance to really do well. You can get started a couple of weeks earlier by starting your bishop's weed indoors.

Last Frost Date

On average the last frost is on May 15 in Duluth. It might get as low as -30°F during the coldest months of winter.

Since the USDA zone info for Duluth is an average the actual date of last frost will vary from year to year. Since half of the time in Duluth it frosts late in the year after May 15 be ready to protect your bishop's weed if you have one of those late frosts.

USDA Zone Info for Duluth

Here is the info for USDA Zone 4a.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-30°F
Highest Expected Low	-25°F

This means that on a really cold year, the coldest it will get is -30°F. On most years you should be prepared to experience lows near -25°F.

Plants to Grow in Duluth

You may be interested in your other planting guides for Duluth.