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.

The earliest that you can plant delphinium in Columbia can be figured out 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 well in very little cold which means that you can plant them slightly earlier in the year than other plants that might not handle the cold.

The earliest that you can plant delphinium in Columbia 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 grow to maturity. 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 Columbia. In the coldest months of winter you should expect an average low temperature of -10°F.

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 Columbia and it will vary from year to year. Half of the time in Columbia you get a frost after April 15 so just be sure to be ready to cover your delphinium if you have a surprise late frost.

USDA Zone Info for Columbia

Here is the info for USDA Zone 6a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-10°F
Highest Expected Low	-5°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 -5°F.

Plants to Grow in Columbia

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