Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

In Palo Alto you can determine when it's a good idea to plant datura by referring to the USDA zone info.

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 plants that are more sensitive to the cold.

The earliest that you can plant datura in Palo Alto 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. Any later than that and your datura may not have a chance to fully mature. You can get started a couple of weeks earlier by starting your datura indoors.

Last Frost Date

On average the last frost when the weather gets warmer is on February 15 in Palo Alto. You can expect an average low temperature of 25°F in the coldest months of winter.

Since the USDA zone info for Palo Alto is an average the actual date of last frost will vary from year to year. Half of the time in Palo Alto you get surprised by a frost after February 15 so be sure to be ready to protect your datura in the event of a late frost.

USDA Zone Info for Palo Alto

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 Palo Alto

You may be interested in your other planting guides for Palo Alto.