One of the best tools that you have as gardeners to help us estimate your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

One way of estimating when it's possible to plant onions is to consult the USDA zone info for Tustin.

Planting Calendar for Onions

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

Onions do well in cold which means that you can plant them much earlier than plants that are more sensitive to the cold.

The earliest that you can plant onions in Tustin 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. Any later than that and 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 couple of weeks earlier.

Last Frost Date

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

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 Tustin and it is different every year. Half of the time in Tustin there is a last frost after January 31 so make sure that you are ready to cover your onions in the event of a surprise late frost.

USDA Zone Info for Tustin

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 Tustin

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