One of the best tools that you have as gardeners to help us figure out your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

One way of determining when it's a good idea to plant delphinium is to examine the USDA zone info for River Forest.

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 means 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 River Forest 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. 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

In River Forest the average date of last frost happens on April 15. In the coldest months of winter you can expect an average low temperature of -10°F.

Just be sure to remember that the actual date of last frost is just an average because it is based on the USDA zone info for River Forest and it is different every year. Since half of the time in River Forest there is a last frost after April 15 be ready to protect your delphinium in the event of one of those late frosts.

USDA Zone Info for River Forest

Here is the info for USDA Zone 6a.

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

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

Plants to Grow in River Forest

You may be interested in your other planting guides for River Forest.