Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

By looking at the USDA zone info for Rialto it's possible to estimate when to plant dahlia.

Planting Calendar for Dahlia

Frost tolerance for dahlia:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

Since dahlia require warm weather it's important to wait until after the last frost before you can plant them.

The earliest that you can plant dahlia 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 dahlia and expect a good harvest is probably September. You probably don't want to wait any later than that or else your dahlia may not have a chance to really do well. If you are starting your dahlia indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

In Rialto the average date of last frost happens on January 31. 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 is an average because it is based on the USDA zone info for Rialto and it changes from year to year. Half of the time in Rialto you get surprised by a frost after January 31 so make sure that you are ready to protect your dahlia 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.