Before planting it is a good idea to find your USDA Zone info to estimate 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 way of getting a good idea when it's a good idea to plant delphinium is to check out the USDA zone info for Robinson.

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 ok in moderate cold which tells us that you can start planting them slightly earlier than plants that are more sensitive to the cold.

The earliest that you can plant delphinium in Robinson 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. You probably don't want to wait any later than that or else your delphinium may not have a chance to fully mature. You can get started a couple of weeks earlier by starting your delphinium indoors.

Last Frost Date

In Robinson the average date of last frost happens on April 15. You should expect an average low temperature of -10°F in the coldest months of winter.

Since the USDA zone info for Robinson is not always accurate the actual date of last frost can change quite a bit from year to year. Half of the time in Robinson it frosts late in the year after April 15 so just be sure to be ready to cover your delphinium in the event of one of those late frosts.

USDA Zone Info for Robinson

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 Robinson

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