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 making a decision about when it's a good idea to plant delphinium is to refer to the USDA zone info for Antioch.

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.

Since delphinium are barely cold tolerant you can plant them just a tiny bit earlier in the year than other plants that might not handle the cold.

The earliest that you can plant delphinium in Antioch is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant delphinium and expect a good harvest is probably August. You probably don't want to wait any later than that or else your delphinium may not have a chance to fully mature. You can get started a few weeks earlier by starting your delphinium indoors.

Last Frost Date

The average date of last frost is April 15 in Antioch. It might get as low as -15°F during the coldest months of winter.

Keep in mind that USDA zone info for Antioch is just an average and the actual date of last frost can change quite a bit from year to year. Half of the time in Antioch you get a frost after April 15 so make sure that you are prepared to protect your delphinium in the event of a surprise late frost.

USDA Zone Info for Antioch

Here is the info for USDA Zone 5b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-15°F
Highest Expected Low	-10°F

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Antioch

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