One of the first steps you take when you are making a decision about 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.

A common way of estimating when it's the best time to plant dahlia is to examine the USDA zone info for Atherton.

Planting Calendar for Dahlia

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

You should not plant dahlia until after the last frost has passed because they require warm weather.

The earliest that you can plant dahlia 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 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 fully mature. Starting your dahlia indoors is a great way to get them started a few weeks earlier.

Last Frost Date

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

Since the USDA zone info for Atherton is an average the actual date of last frost will vary from year to year. Since half of the time in Atherton last frost occurs after February 15 be ready to protect your dahlia if you have one of those late frosts.

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.