The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

One way of figuring out when you can plant cosmos is to examine the USDA zone info for Costa Mesa.

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.

You can plant cosmos just a tiny bit earlier in the year because they are barely cold tolerant.

The earliest that you can plant cosmos in Costa Mesa 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. You can get started a couple of weeks earlier by starting your cosmos indoors.

Last Frost Date

On average the last frost when the weather gets warmer is on January 31 in Costa Mesa. It might get as low as 35°F during the coldest months of winter.

It's important to remember that USDA zone info for Costa Mesa is an average and the actual date of last frost changes from year to year. Half of the time in Costa Mesa it frosts late in the year after January 31 so just be sure to be ready to cover your cosmos in the event of a late frost.

USDA Zone Info for Costa Mesa

Here is the info for USDA Zone 10b.

Average Date of Last Frost (spring)	January 31
Average Date of First Frost (fall)	December 15
Lowest Expected Low	35°F
Highest Expected Low	40°F

This means that on a really cold year, the coldest it will get is 35°F. On most years you should be prepared to experience lows near 40°F.

Plants to Grow in Costa Mesa

You may be interested in your other planting guides for Costa Mesa.