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.

The USDA zone info for Fontana can be read to estimate when it's possible to plant tree onions.

Planting Calendar for Tree onions

Frost tolerance for tree onions:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Tree onions can survive in very little cold which tells us that you can plant them just a tiny bit earlier in the year than other frost tender plants.

The earliest that you can plant tree onions in Fontana 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 tree onions and expect a good harvest is probably September. Any later than that and your tree onions may not have a chance to fully mature. You can get started a little bit earlier by starting your tree onions indoors.

Last Frost Date

The average date of last frost is January 31 in Fontana. In the coldest months of winter you should expect an average low temperature of 30°F.

Since the USDA zone info for Fontana is just an average the actual date of last frost is different every year. Since half of the time in Fontana last frost occurs after January 31 be ready to protect your tree onions if you have one of those late frosts.

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.