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.

The USDA zone info for San Luis Obispo can be read to determine when 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 do well in mild cold which tells us that you can plant them slightly earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant delphinium in San Luis Obispo 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 fully mature. Starting your delphinium indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

In San Luis Obispo the average date of last frost happens on February 15. In the coldest months of winter you should expect an average low temperature of 25°F.

Just be sure to remember that USDA zone info for San Luis Obispo is an average and the actual date of last frost changes from year to year. Half of the time in San Luis Obispo you get a frost after February 15 so be sure to be ready to cover your delphinium if you have a late frost.

USDA Zone Info for San Luis Obispo

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 San Luis Obispo

You may be interested in your other planting guides for San Luis Obispo.