One of the first steps you take when you are estimating your gardening schedule is find your USDA Zone info. 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 lithospermum in Boston should be determined by reviewing the USDA zone info.

Planting Calendar for Lithospermum

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

Since lithospermum require warm 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 lithospermum in Boston 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 lithospermum and expect a good harvest is probably August. If you wait any later than that and your lithospermum may not have a chance to fully mature. Starting your lithospermum indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

In Boston the average date of last frost happens on April 15. In the coldest months of winter you should expect an average low temperature of -5°F.

Keep in mind that the actual date of last frost is just an average because it is based on the USDA zone info for Boston and it changes from year to year. Since half of the time in Boston last frost occurs after April 15 be ready to protect your lithospermum if you have a late frost.

USDA Zone Info for Boston

Here is the info for USDA Zone 6b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-5°F
Highest Expected Low	0°F

This means that on a really cold year, the coldest it will get is -5°F. On most years you should be prepared to experience lows near 0°F.

Plants to Grow in Boston

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