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 Cottonwood should be reviewed to figure out when it's a good idea to plant zinnia.

Planting Calendar for Zinnia

Frost tolerance for zinnia:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

It's not a good idea to plant zinnia until after the last frost because they require warm weather.

The earliest that you can plant zinnia in Cottonwood is April. However, you really should wait until May if you don't want to take any chances.

The last month that you can plant zinnia and expect a good harvest is probably August. Any later than that and your zinnia may not have a chance to fully mature. If you are starting your zinnia indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

On average the last frost has passed is on March 15 in Cottonwood. It might get as low as 15°F during the coldest months of winter.

Since the USDA zone info for Cottonwood is not always accurate the actual date of last frost will vary from year to year. Half of the time in Cottonwood there is a last frost after March 15 so make sure that you are ready to cover your zinnia if you have a surprise late frost.

USDA Zone Info for Cottonwood

Here is the info for USDA Zone 8b.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	15°F
Highest Expected Low	20°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 20°F.

Plants to Grow in Cottonwood

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