When to Plant Cosmos in Lafayette, CO

Before planting it is a good idea to find your USDA Zone info to figure out 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 Lafayette by referring to 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.

Since cosmos are barely cold tolerant you can plant them just a tiny bit earlier in the year than more sensitive plants.

JanFebMarAprMayJunJulAugSepOctNovDec
Legend 
A good time to plant cosmos
Possibly ok, but a risky time to plant cosmos
Probably not a good time to plant cosmos

The earliest that you can plant cosmos in Lafayette 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

In Lafayette the average date of last frost happens on April 15. You should expect an average low temperature of -15°F in the coldest months of winter.

Remember that the actual date of last frost is an average because it is based on the USDA zone info for Lafayette and it will vary from year to year. Half of the time in Lafayette it frosts late in the year after April 15 so just be sure to be ready to cover your cosmos if you have one of those late frosts.

USDA Zone Info for Lafayette

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 Lafayette

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