The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. 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 Rialto can be used to determine when it's a good idea to plant nierembergia.

Planting Calendar for Nierembergia

Frost tolerance for nierembergia:	Not tolerant of frost.
When to plant:	After the last frost has passed.

Since nierembergia require warm weather you must wait until after the last frost when the weather gets warmer before you can plant them.

The earliest that you can plant nierembergia 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 nierembergia and expect a good harvest is probably September. If you wait any later than that and your nierembergia may not have a chance to fully mature. If you are starting your nierembergia indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

On average all chance of frost has passed is on 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 is just an average the actual date of last frost changes from year to year. Half of the time in Rialto last frost occurs after January 31 so be sure to be ready to protect your nierembergia if you have one of those late frosts.

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.