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

The first opportunity to plant zinnia in South San Francisco can be figured out by using the USDA zone info.

Planting Calendar for Zinnia

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

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

The earliest that you can plant zinnia in South San Francisco 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. If you wait any later than that and your zinnia may not have a chance to grow to maturity. You can get started a few weeks earlier by starting your zinnia indoors.

Last Frost Date

On average the last frost is on January 31 in South San Francisco. It might get as low as 30°F during the coldest months of winter.

It's important to remember that USDA zone info for South San Francisco is an average and the actual date of last frost will vary from year to year. Half of the time in South San Francisco last frost occurs after January 31 so be sure to be ready to cover your zinnia in the event of a late frost.

USDA Zone Info for South San Francisco

Here is the info for USDA Zone 10a.

Average Date of Last Frost (spring)	January 31
Average Date of First Frost (fall)	December 15
Lowest Expected Low	30°F
Highest Expected Low	35°F

This means that on a really cold year, the coldest it will get is 30°F. On most years you should be prepared to experience lows near 35°F.

Plants to Grow in South San Francisco

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