One of the best tools that you have as gardeners to help us determine your gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

It's possible to estimate when to plant delphinium by looking at the USDA zone info for Clay.

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 one of those plants that can tolerate a tiny bit of cold weather you can plant them just a tiny bit earlier in the year than other frost tender plants.

The earliest that you can plant delphinium in Clay 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. If you wait any later than that and 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

On average the last frost has passed is on April 15 in Clay. You should expect an average low temperature of 5°F in the coldest months of winter.

Always keep in mind that the actual date of last frost is not always accurate because it is based on the USDA zone info for Clay and it is different every year. Half of the time in Clay you get surprised by a frost after April 15 so just be sure to be ready to protect your delphinium if you have a late frost.

USDA Zone Info for Clay

Here is the info for USDA Zone 7b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	5°F
Highest Expected Low	10°F

This means that on a really cold year, the coldest it will get is 5°F. On most years you should be prepared to experience lows near 10°F.

Plants to Grow in Clay

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