One of the first steps you take when you are making a decision about your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

You can figure out when to plant delphinium in Princeton 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.

Delphinium do ok in some cold which means that you can plant them a bit earlier in the year than other plants that might not handle the cold.

The earliest that you can plant delphinium in Princeton 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 really do well. If you are starting your delphinium indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

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

It's important to remember that the actual date of last frost is an average because it is based on the USDA zone info for Princeton and it changes from year to year. Half of the time in Princeton last frost occurs after April 15 so be sure to be ready to protect your delphinium in the event of one of those late frosts.

USDA Zone Info for Princeton

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 Princeton

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