One of the first steps you take when you are estimating 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.

In Mill Valley you can determine when it's a good idea to plant dahlia by looking at the USDA zone info.

Planting Calendar for Dahlia

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

Dahlia require warm weather which tells us that it's necessary to wait until it warms up after the last frost when the weather gets warmer before you can plant them.

The earliest that you can plant dahlia in Mill Valley 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. Any later than that and your dahlia may not have a chance to grow to maturity. You can get started a few weeks earlier by starting your dahlia indoors.

Last Frost Date

On average the last frost is on January 31 in Mill Valley. It might get as low as 30°F during the coldest months of winter.

Since the USDA zone info for Mill Valley is an average the actual date of last frost is different every year. Half of the time in Mill Valley there is a last frost after January 31 so be sure to be ready to protect your dahlia in the event of a surprise late frost.

USDA Zone Info for Mill Valley

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 Mill Valley

You may be interested in your other planting guides for Mill Valley.