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

It's possible to figure out when it's the best time to plant pearl onions by checking out the USDA zone info for San Bruno.

Planting Calendar for Pearl onions

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

Pearl onions do ok in very little cold which tells us that you can plant them slightly earlier in the year than more sensitive plants.

The earliest that you can plant pearl onions in San Bruno 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 pearl onions and expect a good harvest is probably September. Any later than that and your pearl onions may not have a chance to grow to maturity. If you are starting your pearl 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 San Bruno. In the coldest months of winter you should expect an average low temperature of 30°F.

Remember that the actual date of last frost is an average because it is based on the USDA zone info for San Bruno and it will vary from year to year. Half of the time in San Bruno it frosts late in the year after January 31 so just be sure to be ready to cover your pearl onions in the event of a surprise late frost.

USDA Zone Info for San Bruno

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 San Bruno

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