When can I plant Onions in Zone 9b

The USDA Zone info is a great tool for gardeners to help us figure out our gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for our area.

The first opportunity to plant onions in Zone 9b can be figured out by using the USDA zone info.


Planting Calendar for Onions

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

Since onions do well in cold you can plant them earlier in the year than plants that are more sensitive to the cold.

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 9b 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 fully mature. 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 the last frost when the weather gets warmer is on February 15 in Zone 9b. It might get as low as 25°F during the coldest months of winter.

Always keep in mind that our actual date of last frost is not always accurate because it is based on the USDA zone info for Zone 9b and it can change quite a bit from year to year. Since half of the time in Zone 9b we get surprised by a frost after February 15 be ready to cover your onions in the event of a surprise late frost.

USDA Zone Info for Zone 9b

Here is the info for USDA Zone 9b.

Average Date of Last Frost (spring)February 15
Average Date of First Frost (fall)December 15
Lowest Expected Low25°F
Highest Expected Low30°F

This means that on a really cold year, the coldest it will get is 25°F. On most years you should be prepared to experience lows near 30°F.

Plants to Grow in Zone 9b

You may be interested in our other planting guides for Zone 9b.