When to Plant Cosmos in Pleasanton, CA

One of the first steps you take when you are determining your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The first opportunity to plant cosmos in Pleasanton can be determined 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.

Cosmos tend to make it in very little cold which tells us that you can plant them a bit earlier in the year than plants that are more sensitive to the cold.

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 Pleasanton is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant cosmos and expect a good harvest is probably September. If you wait any later than that and your cosmos may not have a chance to grow to maturity. Starting your cosmos indoors is a great way to get them started a few weeks earlier.

Last Frost Date

In Pleasanton the average date of last frost happens on February 15. You can expect an average low temperature of 25°F in the coldest months of winter.

Since the USDA zone info for Pleasanton may not be accurate from year to year the actual date of last frost changes from year to year. Since half of the time in Pleasanton it frosts late in the year after February 15 be ready to protect your cosmos if you have a surprise late frost.

USDA Zone Info for Pleasanton

Here is the info for USDA Zone 9b.

Average Date of Last Frost (spring)February 15
Average Date of First Frost (fall)December 15
Lowest Expected Low25°F
Highest Expected Low30°F

This means that on a really cold year, the coldest it will get is 25°F. On most years you should be prepared to experience lows near 30°F.

Plants to Grow in Pleasanton

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