One of the first steps you take when you are figuring out your gardening schedule is find your USDA Zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

By using the USDA zone info for Zone 10a you will be able to determine when it's the best time 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.

Onions are one of those plants that can tolerate quite a bit of cold weather which tells us that you can start planting them much earlier than more sensitive plants.

The earliest that you can plant onions in Zone 10a 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 grow to maturity. 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

On average the last frost has passed is on January 31 in Zone 10a. It might get as low as 30°F during the coldest months of winter.

Since the USDA zone info for Zone 10a is an average the actual date of last frost will vary from year to year. Since half of the time in Zone 10a there is a last frost after January 31 be ready to cover your onions if you have a late frost.

USDA Zone Info for Zone 10a

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 Zone 10a

You may be interested in your other planting guides for Zone 10a.