The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

You should be able to figure out when it's the best time to plant bishop's weed by referring to the USDA zone info for Waltham.

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.

Since bishop's weed do well in cold you can plant them quite a bit earlier in the year than more sensitive plants.

The earliest that you can plant bishop's weed in Waltham is February. However, you really should wait until March 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 September. If you wait any later than that and your bishop's weed may not have a chance to really do well. You can get started a little bit earlier by starting your bishop's weed indoors.

Last Frost Date

On average the last frost is on April 15 in Waltham. It might get as low as -10°F during the coldest months of winter.

Remember that the actual date of last frost is just an average because it is based on the USDA zone info for Waltham and it changes from year to year. Half of the time in Waltham there is a last frost after April 15 so be sure to be ready to cover your bishop's weed in the event of a late frost.

USDA Zone Info for Waltham

Here is the info for USDA Zone 6a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-10°F
Highest Expected Low	-5°F

This means that on a really cold year, the coldest it will get is -10°F. On most years you should be prepared to experience lows near -5°F.

Plants to Grow in Waltham

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