Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

You should be able to determine when it's possible to plant ageratum by looking at the USDA zone info for Romulus.

Planting Calendar for Ageratum

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

You can not plant ageratum until after all chance of frost has passed because they require warm weather.

The earliest that you can plant ageratum in Romulus 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. You probably don't want to wait any later than that or else 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 Romulus. You can expect an average low temperature of -10°F in the coldest months of winter.

Since the USDA zone info for Romulus is just an average the actual date of last frost changes from year to year. Since half of the time in Romulus you get surprised by a frost after April 15 be ready to protect your ageratum in the event of one of those late frosts.

USDA Zone Info for Romulus

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 Romulus

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