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

You can determine when you can plant cosmos in Lewiston by using the USDA zone info.

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 a bit earlier in the year because they are one of those plants that can tolerate a tiny bit of cold weather.

The earliest that you can plant cosmos in Lewiston 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. Any later than that and your cosmos may not have a chance to fully mature. You can get started a couple of weeks earlier by starting your cosmos indoors.

Last Frost Date

The average date of last frost is April 15 in Lewiston. In the coldest months of winter you can expect an average low temperature of -15°F.

Since the USDA zone info for Lewiston is an average the actual date of last frost changes from year to year. Half of the time in Lewiston last frost occurs after April 15 so always be ready to protect your cosmos if you have a surprise late frost.

USDA Zone Info for Lewiston

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 Lewiston

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