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

In Fullerton you can estimate when it's possible to plant onions by using the USDA zone info.

Planting Calendar for Onions

Frost tolerance for onions:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Since onions do well in cold you can plant them earlier in the year than other plants that might not handle the cold.

The earliest that you can plant onions in Fullerton is January. However, you really should wait until February if you don't want to take any chances.

The last month that you can plant onions and expect a good harvest is probably October. You probably don't want to wait any later than that or else your onions may not have a chance to really do well. If you are starting your onions indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

In Fullerton the average date of last frost happens on January 31. It might get as low as 30°F during the coldest months of winter.

Keep in mind that USDA zone info for Fullerton is an average and the actual date of last frost is different every year. Since half of the time in Fullerton it frosts late in the year after January 31 be ready to protect your onions if you have a surprise late frost.

USDA Zone Info for Fullerton

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 Fullerton

You may be interested in your other planting guides for Fullerton.