The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A common way of figuring out when it's a good idea to plant dahlia is to use the USDA zone info for Calistoga.

Planting Calendar for Dahlia

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

It's a bad idea to plant dahlia until after the last frost when the weather gets warmer because they are not cold tolerant.

The earliest that you can plant dahlia in Calistoga 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 really do well. Starting your dahlia indoors is a great way to get them started a little bit earlier.

Last Frost Date

In Calistoga the average date of last frost happens on February 15. In the coldest months of winter you should expect an average low temperature of 20°F.

Since the USDA zone info for Calistoga may not be accurate from year to year the actual date of last frost will vary from year to year. Half of the time in Calistoga last frost occurs after February 15 so always be ready to protect your dahlia in the event of one of those late frosts.

USDA Zone Info for Calistoga

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 Calistoga

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