One of the best tools that you have as gardeners to help us figure out your gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

By referring to the USDA zone info for Atherton it's a good idea to determine when it's a good idea to plant dahlias.

Planting Calendar for Dahlias

Frost tolerance for dahlias:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

Since dahlias require warm weather it is necessary to wait until after all chance of frost has passed before you can plant them.

The earliest that you can plant dahlias in Atherton 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 dahlias and expect a good harvest is probably September. You probably don't want to wait any later than that or else your dahlias may not have a chance to grow to maturity. You can get started a few weeks earlier by starting your dahlias indoors.

Last Frost Date

The average date of last frost is February 15 in Atherton. In the coldest months of winter you should expect an average low temperature of 25°F.

Just be sure to remember that the actual date of last frost is just an average because it is based on the USDA zone info for Atherton and it can change quite a bit from year to year. Half of the time in Atherton you get a frost after February 15 so just be sure to be ready to cover your dahlias in the event of a late frost.

USDA Zone Info for Atherton

Here is the info for USDA Zone 9b.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	25°F
Highest Expected Low	30°F

This means that on a really cold year, the coldest it will get is 25°F. On most years you should be prepared to experience lows near 30°F.

Plants to Grow in Atherton

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