One of the first steps you take when you are determining 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.

By looking at the USDA zone info for Watertown you will be able to determine when it's possible to plant lithospermum.

Planting Calendar for Lithospermum

Frost tolerance for lithospermum:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

You really shouldn't plant lithospermum until after all chance of frost has passed because they are not cold tolerant.

The earliest that you can plant lithospermum in Watertown 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 really do well. Starting your lithospermum indoors is a great way to get them started a few weeks earlier.

Last Frost Date

The average date of last frost is April 15 in Watertown. It might get as low as -20°F during the coldest months of winter.

Since the USDA zone info for Watertown is an average the actual date of last frost will vary from year to year. Half of the time in Watertown it frosts late in the year after April 15 so make sure that you are prepared to cover your lithospermum in the event of one of those late frosts.

USDA Zone Info for Watertown

Here is the info for USDA Zone 5a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-20°F
Highest Expected Low	-15°F

This means that on a really cold year, the coldest it will get is -20°F. On most years you should be prepared to experience lows near -15°F.

Plants to Grow in Watertown

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