Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

By looking at the USDA zone info for Fontana you will be able to determine when it's a good idea to plant onions.

Planting Calendar for Onions

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

Since onions are one of those plants that can tolerate quite a bit of cold weather 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 Fontana 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. If you wait any later than that and your onions may not have a chance to grow to maturity. Starting your onions indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

On average the last frost has passed is on January 31 in Fontana. You should expect an average low temperature of 30°F in the coldest months of winter.

Just be sure to remember that the actual date of last frost is just an average because it is based on the USDA zone info for Fontana and it is different every year. Since half of the time in Fontana you get surprised by a frost after January 31 be ready to cover your onions if you have a surprise late frost.

USDA Zone Info for Fontana

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 Fontana

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