One of the first steps you take when you are making a decision about 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 way of making a decision about when it's possible to plant delphinium is to check out the USDA zone info for Columbus.

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 ok in mild cold which tells us that you can plant them a bit earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant delphinium in Columbus 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 really do well. 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 March 15 in Columbus. You should expect an average low temperature of 10°F in the coldest months of winter.

Just be sure to remember that USDA zone info for Columbus may not be accurate from year to year and the actual date of last frost changes from year to year. Since half of the time in Columbus it frosts late in the year after March 15 be ready to protect your delphinium in the event of a surprise late frost.

USDA Zone Info for Columbus

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 Columbus

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