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.

One way of making a decision about when it's the best time to plant delphinium is to refer to the USDA zone info for Rocklin.

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 very little 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 Rocklin 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. If you wait 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 few weeks earlier.

Last Frost Date

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

Since the USDA zone info for Rocklin may not be accurate from year to year the actual date of last frost can change quite a bit from year to year. Half of the time in Rocklin there is a last frost after February 15 so always be ready to cover your delphinium in the event of a late frost.

USDA Zone Info for Rocklin

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 Rocklin

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