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.

The USDA zone info for Waltham should be looked at to estimate when it's possible to plant anchusa.

Planting Calendar for Anchusa

Frost tolerance for anchusa:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Anchusa tend to make it in cold weather which means that you can plant them a lot earlier in the year than other frost tender plants.

The earliest that you can plant anchusa 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 anchusa and expect a good harvest is probably September. If you wait any later than that and your anchusa may not have a chance to fully mature. Starting your anchusa indoors is a great way to get them started a few weeks earlier.

Last Frost Date

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

Just be sure to remember that USDA zone info for Waltham is just an average and the actual date of last frost changes from year to year. Since half of the time in Waltham there is a last frost after April 15 be ready to cover your anchusa if you have a surprise 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.