The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

In San Diego you can figure out when it's possible to plant lithospermum by looking at the USDA zone info.

Planting Calendar for Lithospermum

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

Lithospermum are not cold tolerant which means that it is necessary to wait until it warms up after the last frost when the weather gets warmer before you can plant them.

The earliest that you can plant lithospermum in San Diego is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant lithospermum and expect a good harvest is probably September. Any later than that and 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

On average the last frost has passed is on February 15 in San Diego. It might get as low as 20°F during the coldest months of winter.

Always keep in mind that the actual date of last frost is an average because it is based on the USDA zone info for San Diego and it changes from year to year. Half of the time in San Diego you get a frost after February 15 so always be ready to protect your lithospermum if you have one of those late frosts.

USDA Zone Info for San Diego

Here is the info for USDA Zone 9a.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	20°F
Highest Expected Low	25°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 25°F.

Plants to Grow in San Diego

You may be interested in your other planting guides for San Diego.