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.

The USDA zone info for Diamond Bar can be reviewed to determine when it's the best time to plant tomatos.

Planting Calendar for Tomatos

Frost tolerance for tomatos:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

Tomatos do not do well in cold weather which means that you need to wait until it warms up after the last frost when the weather gets warmer before you can plant them.

The earliest that you can plant tomatos 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 tomatos and expect a good harvest is probably September. Any later than that and your tomatos may not have a chance to fully mature. If you are starting your tomatos indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

On average all chance of frost has passed is on January 31 in Diamond Bar. In the coldest months of winter you can expect an average low temperature of 30°F.

Since the USDA zone info for Diamond Bar is not always accurate the actual date of last frost can change quite a bit from year to year. Half of the time in Diamond Bar you get a frost after January 31 so make sure that you are prepared to cover your tomatos in the event of a late frost.

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.