One of the best tools that you have as gardeners to help us figure out your gardening schedule is the 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.

A way of making a decision about when it's a good idea to plant cosmos is to refer to the USDA zone info for Bellingham.

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 one of those plants that can tolerate a tiny bit of cold weather 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 Bellingham 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. If you wait any later than that and your cosmos may not have a chance to really do well. You can get started a couple of weeks earlier by starting your cosmos indoors.

Last Frost Date

In Bellingham the average date of last frost happens on March 15. You should expect an average low temperature of 10°F in the coldest months of winter.

Keep in mind that the actual date of last frost is just an average because it is based on the USDA zone info for Bellingham and it will vary from year to year. Half of the time in Bellingham it frosts late in the year after March 15 so just be sure to be ready to protect your cosmos in the event of a late frost.

USDA Zone Info for Bellingham

Here is the info for USDA Zone 8a.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	10°F
Highest Expected Low	15°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 15°F.

Plants to Grow in Bellingham

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