One of the first steps you take when you are estimating your gardening schedule is find your 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.

One way of determining when it's possible to plant cosmos is to consult the USDA zone info for Tiffin.

Planting Calendar for Cosmos

Frost tolerance for cosmos:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

You can plant cosmos slightly earlier in the year because they are barely cold tolerant.

The earliest that you can plant cosmos in Tiffin 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 cosmos and expect a good harvest is probably August. You probably don't want to wait any later than that or else your cosmos may not have a chance to fully mature. Starting your cosmos indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

On average the last frost has passed is on April 15 in Tiffin. In the coldest months of winter you should expect an average low temperature of -10°F.

Since the USDA zone info for Tiffin is not always accurate the actual date of last frost will vary from year to year. Half of the time in Tiffin last frost occurs after April 15 so always be ready to protect your cosmos in the event of one of those late frosts.

USDA Zone Info for Tiffin

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 Tiffin

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