One of the best tools that you have as gardeners to help us figure out your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

By referring to the USDA zone info for Orinda it's possible to figure out when it's the best time 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 tend to make it in mild cold which means that you can plant them a bit earlier in the year than other plants that might not handle the cold.

The earliest that you can plant cosmos in Orinda 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. You probably don't want to wait any later than that or else your cosmos may not have a chance to really do well. If you are starting your cosmos indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

On average the last frost is on February 15 in Orinda. In the coldest months of winter you should expect an average low temperature of 25°F.

Always keep in mind that the actual date of last frost is an average because it is based on the USDA zone info for Orinda and it changes from year to year. Half of the time in Orinda you get surprised by a frost after February 15 so make sure that you are ready to protect your cosmos in the event of a late frost.

USDA Zone Info for Orinda

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 Low	25°F
Highest Expected Low	30°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 Orinda

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