One of the first steps you take when you are determining 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.

A common way of estimating when it's the best time to plant delphinium is to look at the USDA zone info for Mount Vernon.

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 one of those plants that can tolerate a tiny bit of cold weather which tells us that you can get them planted just a bit earlier than plants that are more sensitive to the cold.

The earliest that you can plant delphinium in Mount Vernon 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. If you are starting your delphinium indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

The average date of last frost is March 15 in Mount Vernon. You can expect an average low temperature of 10°F in the coldest months of winter.

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 Mount Vernon and it will vary from year to year. Since half of the time in Mount Vernon you get a frost after March 15 be ready to cover your delphinium if you have a late frost.

USDA Zone Info for Mount Vernon

Here is the info for USDA Zone 8a.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	10°F
Highest Expected Low	15°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 15°F.

Plants to Grow in Mount Vernon

You may be interested in your other planting guides for Mount Vernon.