One of the best tools that you have as gardeners to help us figure out 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 USDA zone info for Marengo should be reviewed to figure out when you can plant dahlias.

Planting Calendar for Dahlias

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

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

The earliest that you can plant dahlias in Marengo 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 dahlias and expect a good harvest is probably August. If you wait any later than that and your dahlias may not have a chance to really do well. You can get started a couple of weeks earlier by starting your dahlias indoors.

Last Frost Date

On average the last frost has passed is on April 15 in Marengo. In the coldest months of winter you should expect an average low temperature of -15°F.

Since the USDA zone info for Marengo is not always accurate the actual date of last frost is different every year. Half of the time in Marengo you get surprised by a frost after April 15 so just be sure to be ready to cover your dahlias if you have one of those late frosts.

USDA Zone Info for Marengo

Here is the info for USDA Zone 5b.

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

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Marengo

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