When to Plant Delphinium in Zone 1a

One of the best tools that you have as gardeners to help us determine 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.

The earliest that you can plant delphinium in Zone 1a can be estimated by reviewing 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.

You can plant delphinium a bit earlier in the year because they are barely cold tolerant.

JanFebMarAprMayJunJulAugSepOctNovDec
Legend 
A good time to plant delphinium
Possibly ok, but a risky time to plant delphinium
Probably not a good time to plant delphinium

The earliest that you can plant delphinium in Zone 1a is June. However, you really should wait until July if you don't want to take any chances.

The last month that you can plant delphinium and expect a good harvest is probably July. 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 couple of weeks earlier.

Last Frost Date

The average date of last frost is June 15 in Zone 1a. It might get as low as -60°F during the coldest months of winter.

Since the USDA zone info for Zone 1a is not always accurate the actual date of last frost changes from year to year. Since half of the time in Zone 1a there is a last frost after June 15 be ready to cover your delphinium in the event of a late frost.

USDA Zone Info for Zone 1a

Here is the info for USDA Zone 1a.

Average Date of Last Frost (spring)June 15
Average Date of First Frost (fall)July 15
Lowest Expected Low-60°F
Highest Expected Low-55°F

This means that on a really cold year, the coldest it will get is -60°F. On most years you should be prepared to experience lows near -55°F.

Plants to Grow in Zone 1a

You may be interested in your other planting guides for Zone 1a.