The USDA Zone info is a great tool for gardeners to help us determine 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 estimating when to plant delphinium is to refer to the USDA zone info for Alhambra.

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 can survive in mild cold which tells us that 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 delphinium in Alhambra 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. You probably don't want to wait any later than that or else your delphinium may not have a chance to really do well. You can get started a few weeks earlier by starting your delphinium indoors.

Last Frost Date

The average date of last frost is January 31 in Alhambra. You can expect an average low temperature of 30°F in the coldest months of winter.

Since the USDA zone info for Alhambra is not always accurate the actual date of last frost can change quite a bit from year to year. Since half of the time in Alhambra last frost occurs after January 31 be ready to cover your delphinium if you have a late frost.

USDA Zone Info for Alhambra

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 Alhambra

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