Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The first chance to plant delphinium in Carbondale can be determined by referring to the USDA zone info.

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 Carbondale 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. 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 Carbondale. You should expect an average low temperature of -15°F in the coldest months of winter.

Keep in mind that the actual date of last frost is not always accurate because it is based on the USDA zone info for Carbondale and it can change quite a bit from year to year. Half of the time in Carbondale you get surprised by a frost after April 15 so make sure that you are ready to protect your delphinium in the event of one of those late frosts.

USDA Zone Info for Carbondale

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 Carbondale

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