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

The USDA zone info for San Marino should be used to estimate when you can plant bunching onions.

Planting Calendar for Bunching Onions

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

You can plant bunching onions a bit earlier in the year because they are barely cold tolerant.

The earliest that you can plant bunching onions in San Marino 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 bunching onions and expect a good harvest is probably September. If you wait any later than that and your bunching onions may not have a chance to fully mature. Starting your bunching onions indoors is a great way to get them started a few weeks earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on January 31 in San Marino. In the coldest months of winter you should expect an average low temperature of 30°F.

Since the USDA zone info for San Marino is an average the actual date of last frost will vary from year to year. Since half of the time in San Marino it frosts late in the year after January 31 be ready to protect your bunching onions if you have a surprise late frost.

USDA Zone Info for San Marino

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 Marino

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