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.

A common way of estimating when it's a good idea to plant cosmos is to refer to the USDA zone info for Willoughby.

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.

Cosmos are barely cold tolerant which tells us that you can get them planted just a bit earlier than more sensitive plants.

The earliest that you can plant cosmos in Willoughby 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 grow to maturity. Starting your cosmos indoors is a great way to get them started a few weeks earlier.

Last Frost Date

On average the last frost has passed is on April 15 in Willoughby. It might get as low as -5°F during the coldest months of winter.

Remember that USDA zone info for Willoughby is just an average and the actual date of last frost can change quite a bit from year to year. Half of the time in Willoughby you get a frost after April 15 so make sure that you are ready to cover your cosmos in the event of a late frost.

USDA Zone Info for Willoughby

Here is the info for USDA Zone 6b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-5°F
Highest Expected Low	0°F

This means that on a really cold year, the coldest it will get is -5°F. On most years you should be prepared to experience lows near 0°F.

Plants to Grow in Willoughby

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