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.

The USDA zone info for Sonora can be reffered to in order to determine when to plant dahlia.

Planting Calendar for Dahlia

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

Since dahlia do not do well in cold weather you must wait until after the last frost has passed before you can plant them.

The earliest that you can plant dahlia in Sonora is March. However, you really should wait until April 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 grow to maturity. 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 Sonora the average date of last frost happens on February 15. You can expect an average low temperature of 20°F in the coldest months of winter.

Just be sure to remember 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 Sonora and it will vary from year to year. Half of the time in Sonora you get surprised by a frost after February 15 so make sure that you are prepared to cover your dahlia in the event of a surprise late frost.

USDA Zone Info for Sonora

Here is the info for USDA Zone 9a.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	20°F
Highest Expected Low	25°F

This means that on a really cold year, the coldest it will get is 20°F. On most years you should be prepared to experience lows near 25°F.

Plants to Grow in Sonora

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