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

In Diamond Bar you can figure out when it's possible to plant bunching onions by reviewing the USDA zone info.

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.

Since bunching onions are one of those plants that can tolerate a tiny bit of cold weather you can plant them just a tiny bit earlier in the year than other plants that might not handle the cold.

The earliest that you can plant bunching onions in Diamond Bar 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 Diamond Bar the average date of last frost happens on January 31. It might get as low as 30°F during the coldest months of winter.

Since the USDA zone info for Diamond Bar may not be accurate from year to year the actual date of last frost is different every year. Since half of the time in Diamond Bar there is a last frost after January 31 be ready to protect your bunching onions if you have one of those late frosts.

USDA Zone Info for Diamond Bar

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 Diamond Bar

You may be interested in your other planting guides for Diamond Bar.