One of the best tools that you have as gardeners to help us estimate your gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The earliest that you can plant ageratum in Columbus should be figured out by looking at the USDA zone info.

Planting Calendar for Ageratum

Frost tolerance for ageratum:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

Since ageratum require warm weather it is necessary to wait until after the last frost has passed before you can plant them.

The earliest that you can plant ageratum in Columbus is April. However, you really should wait until May if you don't want to take any chances.

The last month that you can plant ageratum and expect a good harvest is probably August. If you wait any later than that and your ageratum may not have a chance to really do well. You can get started a few weeks earlier by starting your ageratum indoors.

Last Frost Date

The average date of last frost is April 15 in Columbus. It might get as low as -10°F during the coldest months of winter.

It's important to remember that USDA zone info for Columbus may not be accurate from year to year and the actual date of last frost can change quite a bit from year to year. Since half of the time in Columbus you get surprised by a frost after April 15 be ready to protect your ageratum if you have a surprise late frost.

USDA Zone Info for Columbus

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 Columbus

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