One of the best tools that you have as gardeners to help us figure out your gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

By checking out the USDA zone info for Port Huron it's a good idea to estimate 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.

Since lithospermum are not cold tolerant it's necessary to wait until after the last frost has passed before you can plant them.

The earliest that you can plant lithospermum in Port Huron 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. You can get started a couple of weeks earlier by starting your lithospermum indoors.

Last Frost Date

In Port Huron the average date of last frost happens on April 15. It might get as low as -10°F during the coldest months of winter.

Keep in mind that USDA zone info for Port Huron is just an average and the actual date of last frost will vary from year to year. Half of the time in Port Huron it frosts late in the year after April 15 so be sure to be ready to cover your lithospermum in the event of a surprise late frost.

USDA Zone Info for Port Huron

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 Port Huron

You may be interested in your other planting guides for Port Huron.