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.

In Eugene you can determine when it's the best time to plant cosmos by checking out 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.

Cosmos do well in some cold which tells us that you can plant them just a tiny bit earlier in the year than other frost tender plants.

The earliest that you can plant cosmos in Eugene 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 fully mature. You can get started a few weeks earlier by starting your cosmos indoors.

Last Frost Date

The average date of last frost is March 15 in Eugene. You can expect an average low temperature of 15°F in the coldest months of winter.

Remember that the actual date of last frost is just an average because it is based on the USDA zone info for Eugene and it is different every year. Half of the time in Eugene last frost occurs after March 15 so just be sure to be ready to cover your cosmos in the event of a surprise late frost.

USDA Zone Info for Eugene

Here is the info for USDA Zone 8b.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	15°F
Highest Expected Low	20°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 20°F.

Plants to Grow in Eugene

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