One of the best tools that you have as gardeners to help us figure out your gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

It's possible to determine when to plant zinnia by looking at the USDA zone info for Oskaloosa.

Planting Calendar for Zinnia

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

Since zinnia require warm weather it's necessary to wait until after all chance of frost has passed before you can plant them.

The earliest that you can plant zinnia in Oskaloosa 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 grow to maturity. Starting your zinnia indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

In Oskaloosa the average date of last frost happens on April 15. You can expect an average low temperature of -15°F in the coldest months of winter.

Just be sure to remember that USDA zone info for Oskaloosa is an average and the actual date of last frost changes from year to year. Since half of the time in Oskaloosa last frost occurs after April 15 be ready to protect your zinnia in the event of a surprise late frost.

USDA Zone Info for Oskaloosa

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 Oskaloosa

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