One of the best tools that you have as gardeners to help us figure out 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 determining when it's possible to plant california poppy is to examine the USDA zone info for Rialto.

Planting Calendar for California Poppy

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

California Poppy are barely cold tolerant which means that you can start planting them slightly earlier than other plants that might not handle the cold.

The earliest that you can plant california poppy 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 california poppy and expect a good harvest is probably September. Any later than that and your california poppy may not have a chance to fully mature. Starting your california poppy indoors is a great way to get them started a few weeks earlier.

Last Frost Date

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

Since the USDA zone info for Rialto may not be accurate from year to year the actual date of last frost will vary from year to year. Half of the time in Rialto it frosts late in the year after January 31 so make sure that you are ready to protect your california poppy if you have a surprise 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.