The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A way of figuring out when it's possible to plant delphinium is to consult the USDA zone info for Potsdam.

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 a bit earlier in the year than more sensitive plants.

The earliest that you can plant delphinium in Potsdam 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 fully mature. Starting your delphinium indoors is a great way to get them started a few weeks earlier.

Last Frost Date

The average date of last frost is May 15 in Potsdam. In the coldest months of winter you can expect an average low temperature of -25°F.

Just be sure to remember that the actual date of last frost is not always accurate because it is based on the USDA zone info for Potsdam and it will vary from year to year. Half of the time in Potsdam last frost occurs after May 15 so make sure that you are prepared to cover your delphinium in the event of a surprise late frost.

USDA Zone Info for Potsdam

Here is the info for USDA Zone 4b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-25°F
Highest Expected Low	-20°F

This means that on a really cold year, the coldest it will get is -25°F. On most years you should be prepared to experience lows near -20°F.

Plants to Grow in Potsdam

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