One of the best tools that you have as gardeners to help us determine 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.

The USDA zone info for Commerce City can be used to figure out when you can plant zinnia.

Planting Calendar for Zinnia

Frost tolerance for zinnia:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

You can not plant zinnia until after the last frost because they require warm weather.

The earliest that you can plant zinnia in Commerce City 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. You probably don't want to wait any later than that or else your zinnia may not have a chance to grow to maturity. You can get started a few weeks earlier by starting your zinnia indoors.

Last Frost Date

The average date of last frost is April 15 in Commerce City. You should expect an average low temperature of -15°F in the coldest months of winter.

It's important to remember that the actual date of last frost is just an average because it is based on the USDA zone info for Commerce City and it will vary from year to year. Half of the time in Commerce City you get a frost after April 15 so make sure that you are ready to protect your zinnia in the event of one of those late frosts.

USDA Zone Info for Commerce City

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 Commerce City

You may be interested in your other planting guides for Commerce City.