One of the best tools that you have as gardeners to help us determine your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A common way of getting a good idea when it's the best time to plant bunching onions is to refer to the USDA zone info for San Luis Obispo.

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.

Bunching Onions do well in mild cold which means that you can plant them a bit earlier in the year than more sensitive plants.

The earliest that you can plant bunching onions in San Luis Obispo 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. 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 little bit earlier.

Last Frost Date

In San Luis Obispo the average date of last frost happens on February 15. It might get as low as 25°F during the coldest months of winter.

Since the USDA zone info for San Luis Obispo is an average the actual date of last frost is different every year. Half of the time in San Luis Obispo you get surprised by a frost after February 15 so make sure that you are prepared to protect your bunching onions if you have one of those late frosts.

USDA Zone Info for San Luis Obispo

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 Luis Obispo

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