One of the best tools that you have as gardeners to help us estimate 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.

One way of estimating when it's a good idea to plant tomatos is to refer to the USDA zone info for San Diego.

Planting Calendar for Tomatos

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

Tomatos do not do well in cold weather 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 tomatos in San Diego is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant tomatos and expect a good harvest is probably September. If you wait any later than that and your tomatos may not have a chance to grow to maturity. If you are starting your tomatos indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

In San Diego the average date of last frost happens on January 31. In the coldest months of winter you should expect an average low temperature of 35°F.

Since the USDA zone info for San Diego is not always accurate the actual date of last frost will vary from year to year. Half of the time in San Diego last frost occurs after January 31 so make sure that you are ready to protect your tomatos if you have one of those late frosts.

USDA Zone Info for San Diego

Here is the info for USDA Zone 10b.

Average Date of Last Frost (spring)	January 31
Average Date of First Frost (fall)	December 15
Lowest Expected Low	35°F
Highest Expected Low	40°F

This means that on a really cold year, the coldest it will get is 35°F. On most years you should be prepared to experience lows near 40°F.

Plants to Grow in San Diego

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