Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

You can determine when you can plant lithospermum in Plymouth by checking out 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 do not do well in cold weather you need to wait until after the last frost before you can plant them.

The earliest that you can plant lithospermum in Plymouth 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. You probably don't want to wait any later than that or else your lithospermum may not have a chance to grow to maturity. If you are starting your lithospermum indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

In Plymouth the average date of last frost happens on April 15. It might get as low as -15°F during the coldest months of winter.

Since the USDA zone info for Plymouth is just an average the actual date of last frost is different every year. Half of the time in Plymouth last frost occurs after April 15 so just be sure to be ready to protect your lithospermum in the event of a late frost.

USDA Zone Info for Plymouth

Here is the info for USDA Zone 5b.

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

Plants to Grow in Plymouth

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