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.

The USDA zone info for Diamond Bar should be reviewed to figure out when it's possible to plant tree onions.

Planting Calendar for Tree onions

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

Tree onions do well in very little 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 tree 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 tree onions and expect a good harvest is probably September. Any later than that and your tree onions may not have a chance to grow to maturity. You can get started a little bit earlier by starting your tree onions indoors.

Last Frost Date

On average the last frost has passed is on January 31 in Diamond Bar. You should expect an average low temperature of 30°F in the coldest months of winter.

It's important to remember that USDA zone info for Diamond Bar may not be accurate from year to year and the actual date of last frost is different every year. Since half of the time in Diamond Bar you get surprised by a frost after January 31 be ready to cover your tree 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.