When can I plant Onions in Zone 10b

One of the best tools that we have as gardeners to help us figure out our gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for our area.

It's possible to estimate when it's possible to plant onions by reviewing the USDA zone info for Zone 10b.


Planting Calendar for Onions

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

Onions do well in cold which tells us that you can plant them much earlier than other frost tender plants.

JanFebMarAprMayJunJulAugSepOctNovDec
Legend 
A good time to plant onions
Possibly ok, but a risky time to plant onions
Probably not a good time to plant onions

The earliest that you can plant onions in Zone 10b 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 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

On average all chance of frost has passed is on January 31 in Zone 10b. We can expect an average low temperature of 35°F in the coldest months of winter.

It's important to remember that our actual date of last frost is an average because it is based on the USDA zone info for Zone 10b and it is different every year. Half of the time in Zone 10b we get a frost after January 31 so just be sure to be ready to protect your onions if we have a surprise late frost.

USDA Zone Info for Zone 10b

Here is the info for USDA Zone 10b.

Average Date of Last Frost (spring)January 31
Average Date of First Frost (fall)December 15
Lowest Expected Low35°F
Highest Expected Low40°F

This means that on a really cold year, the coldest it will get is 35°F. On most years you should be prepared to experience lows near 40°F.

Plants to Grow in Zone 10b

You may be interested in our other planting guides for Zone 10b.