When can I plant Tree onions in Zone 10a

One of the first steps we take when we are estimating our gardening schedule is find our 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.

The first chance to plant tree onions in Zone 10a should be determined by checking out the USDA zone info.


Planting Calendar for Tree onions

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

Tree onions are barely cold tolerant which means that you can plant them slightly earlier than more sensitive plants.

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

The earliest that you can plant tree onions in Zone 10a 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 really do well. Starting your tree onions indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

In Zone 10a the average date of last frost happens on January 31. We should expect an average low temperature of 30°F in the coldest months of winter.

Since the USDA zone info for Zone 10a is just an average our actual date of last frost changes from year to year. Since half of the time in Zone 10a last frost occurs after January 31 be ready to cover your tree onions in the event of 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 Low30°F
Highest Expected Low35°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 our other planting guides for Zone 10a.