One of the first steps you take when you are getting a good idea your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

By referring to the USDA zone info for Rialto you should be able to determine when it's possible to plant regal geranium.

Planting Calendar for Regal Geranium

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

Regal Geranium do well in a tiny bit of cold which tells us 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 regal geranium 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 regal geranium and expect a good harvest is probably September. You probably don't want to wait any later than that or else your regal geranium may not have a chance to grow to maturity. You can get started a couple of weeks earlier by starting your regal geranium indoors.

Last Frost Date

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

Keep in mind that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Rialto and it is different every year. Half of the time in Rialto you get surprised by a frost after January 31 so be sure to be ready to protect your regal geranium in the event of 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.