Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The USDA zone info for Mill Valley should be reffered to in order to figure out when it's a good idea to plant datura.

Planting Calendar for Datura

Frost tolerance for datura:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Since datura are barely cold tolerant you can plant them just a tiny bit earlier in the year than other frost tender plants.

The earliest that you can plant datura 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 datura and expect a good harvest is probably September. You probably don't want to wait any later than that or else your datura may not have a chance to grow to maturity. If you are starting your datura indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

In Mill Valley the average date of last frost happens on January 31. It might get as low as 30°F during the coldest months of winter.

Keep in mind that USDA zone info for Mill Valley is an average and the actual date of last frost will vary from year to year. Half of the time in Mill Valley you get surprised by a frost after January 31 so make sure that you are prepared to cover your datura in the event of a 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.