Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

In San Diego you can determine when it's possible to plant welsh onion by using the USDA zone info.

Planting Calendar for Welsh onion

Frost tolerance for welsh onion:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Welsh onion are barely cold tolerant which means that you can plant them slightly earlier than plants that are more sensitive to the cold.

The earliest that you can plant welsh onion in San Diego 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 welsh onion and expect a good harvest is probably September. Any later than that and your welsh onion may not have a chance to fully mature. If you are starting your welsh onion 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 San Diego. In the coldest months of winter you should expect an average low temperature of 35°F.

Just be sure to remember that USDA zone info for San Diego may not be accurate from year to year and the actual date of last frost can change quite a bit from year to year. Half of the time in San Diego you get a frost after January 31 so be sure to be ready to protect your welsh onion if you have a surprise late frost.

USDA Zone Info for San Diego

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 Low	35°F
Highest Expected Low	40°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 San Diego

You may be interested in your other planting guides for San Diego.