Before planting it is a good idea to find your USDA Zone info to estimate 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.

A common way of estimating when to plant zinnia is to examine the USDA zone info for San Diego.

Planting Calendar for Zinnia

Frost tolerance for zinnia:	Not tolerant of frost.
When to plant:	After the last frost.

Since zinnia do not do well in cold weather you need to wait until after the last frost has passed before you can plant them.

The earliest that you can plant zinnia 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 zinnia and expect a good harvest is probably September. Any later than that and your zinnia may not have a chance to really do well. You can get started a few weeks earlier by starting your zinnia indoors.

Last Frost Date

On average the last frost when the weather gets warmer is on January 31 in San Diego. You can expect an average low temperature of 35°F in the coldest months of winter.

Since the USDA zone info for San Diego is just an average the actual date of last frost is different every year. Since half of the time in San Diego you get a frost after January 31 be ready to protect your zinnia in the event of a surprise late frost.

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.