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 common way of getting a good idea when it's a good idea to plant delphinium is to examine the USDA zone info for Bristol.

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 tend to make it in a tiny bit of cold which tells us that you can plant them a bit earlier in the year than more sensitive plants.

The earliest that you can plant delphinium in Bristol 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. 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

On average the last frost is on April 15 in Bristol. It might get as low as 0°F during the coldest months of winter.

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 Bristol and it changes from year to year. Half of the time in Bristol there is a last frost after April 15 so be sure to be ready to protect your delphinium if you have a surprise late frost.

USDA Zone Info for Bristol

Here is the info for USDA Zone 7a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	0°F
Highest Expected Low	5°F

This means that on a really cold year, the coldest it will get is 0°F. On most years you should be prepared to experience lows near 5°F.

Plants to Grow in Bristol

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