Before planting it is a good idea to find your USDA Zone info to figure out 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 Los Altos should be reviewed to figure out when it's possible to plant delphinium.

Planting Calendar for Delphinium

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

Delphinium are barely cold tolerant which means that you can get them planted just a bit earlier than more sensitive plants.

The earliest that you can plant delphinium in Los Altos 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 delphinium and expect a good harvest is probably September. Any later than that and your delphinium may not have a chance to grow to maturity. Starting your delphinium indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

On average all chance of frost has passed is on February 15 in Los Altos. You can expect an average low temperature of 25°F in the coldest months of winter.

Keep in mind that the actual date of last frost is not always accurate because it is based on the USDA zone info for Los Altos and it can change quite a bit from year to year. Half of the time in Los Altos you get a frost after February 15 so always be ready to cover your delphinium in the event of a surprise late frost.

USDA Zone Info for Los Altos

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 Los Altos

You may be interested in your other planting guides for Los Altos.