One of the best tools that you have as gardeners to help us figure out your gardening schedule is the USDA zone info. 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 to plant delphinium is to consult the USDA zone info for New London.

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 get them planted just a bit earlier than other frost tender plants.

The earliest that you can plant delphinium in New London 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. You can get started a few weeks earlier by starting your delphinium indoors.

Last Frost Date

On average the last frost when the weather gets warmer is on April 15 in New London. It might get as low as -20°F during the coldest months of winter.

It's important to remember that USDA zone info for New London is not always accurate and the actual date of last frost changes from year to year. Since half of the time in New London it frosts late in the year after April 15 be ready to protect your delphinium in the event of a late frost.

USDA Zone Info for New London

Here is the info for USDA Zone 5a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-20°F
Highest Expected Low	-15°F

This means that on a really cold year, the coldest it will get is -20°F. On most years you should be prepared to experience lows near -15°F.

Plants to Grow in New London

You may be interested in your other planting guides for New London.