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.

The best time to plant pearl onions in Rialto should be estimated by reviewing the USDA zone info.

Planting Calendar for Pearl onions

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

Since pearl onions do ok in moderate cold you can plant them a bit earlier in the year than other frost tender plants.

The earliest that you can plant pearl onions in Rialto 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 pearl onions and expect a good harvest is probably September. If you wait any later than that and your pearl onions may not have a chance to grow to maturity. Starting your pearl onions indoors is a great way to get them started a little bit earlier.

Last Frost Date

The average date of last frost is January 31 in Rialto. You can expect an average low temperature of 30°F in the coldest months of winter.

It's important to remember that USDA zone info for Rialto is not always accurate and the actual date of last frost changes from year to year. Half of the time in Rialto you get surprised by a frost after January 31 so just be sure to be ready to cover your pearl onions if you have a late frost.

USDA Zone Info for Rialto

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 Rialto

You may be interested in your other planting guides for Rialto.