Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The USDA zone info for Humboldt can be looked at to determine when it's possible to plant cosmos.

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 can survive in very little cold which means that you can plant them slightly earlier in the year than other frost tender plants.

The earliest that you can plant cosmos in Humboldt 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. If you are starting your cosmos indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on April 15 in Humboldt. In the coldest months of winter you should expect an average low temperature of 0°F.

Always keep in mind that USDA zone info for Humboldt may not be accurate from year to year and the actual date of last frost can change quite a bit from year to year. Half of the time in Humboldt you get a frost after April 15 so make sure that you are prepared to protect your cosmos in the event of a surprise late frost.

USDA Zone Info for Humboldt

Here is the info for USDA Zone 7a.

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

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

Plants to Grow in Humboldt

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