One of the best tools that you have as gardeners to help us determine your 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 your area.

One way of estimating when you can plant pearl onions is to check out the USDA zone info for San Ramon.

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 some cold which means that you can plant them slightly earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant pearl onions in San Ramon 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. If you wait any later than that and your pearl onions may not have a chance to grow to maturity. You can get started a little bit earlier by starting your pearl onions indoors.

Last Frost Date

In San Ramon the average date of last frost happens on February 15. In the coldest months of winter you should expect an average low temperature of 25°F.

Remember that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for San Ramon and it is different every year. Half of the time in San Ramon there is a last frost after February 15 so make sure that you are ready to protect your pearl onions in the event of a surprise late frost.

USDA Zone Info for San Ramon

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 Low	25°F
Highest Expected Low	30°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 San Ramon

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