Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

A common way of estimating when it's a good idea to plant delphinium is to check out the USDA zone info for Hibbing.

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 are barely cold tolerant which tells us that you can start planting them slightly earlier than other frost tender plants.

The earliest that you can plant delphinium in Hibbing is April. However, you really should wait until May 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 grow to maturity. You can get started a little bit earlier by starting your delphinium indoors.

Last Frost Date

The average date of last frost is May 15 in Hibbing. It might get as low as -35°F during the coldest months of winter.

Since the USDA zone info for Hibbing is not always accurate the actual date of last frost changes from year to year. Since half of the time in Hibbing it frosts late in the year after May 15 be ready to protect your delphinium in the event of one of those late frosts.

USDA Zone Info for Hibbing

Here is the info for USDA Zone 3b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-35°F
Highest Expected Low	-30°F

This means that on a really cold year, the coldest it will get is -35°F. On most years you should be prepared to experience lows near -30°F.

Plants to Grow in Hibbing

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