One of the first steps you take when you are determining your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

By looking at the USDA zone info for Grinnell it's possible to determine when you can plant centaurea.

Planting Calendar for Centaurea

Frost tolerance for centaurea:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Centaurea do ok in some cold which means that you can plant them a little earlier in the year than more sensitive plants.

The earliest that you can plant centaurea in Grinnell 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 centaurea and expect a good harvest is probably September. Any later than that and your centaurea may not have a chance to really do well. You can get started a couple of weeks earlier by starting your centaurea indoors.

Last Frost Date

On average the last frost when the weather gets warmer is on April 15 in Grinnell. In the coldest months of winter you should expect an average low temperature of -20°F.

Just be sure to remember that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Grinnell and it can change quite a bit from year to year. Half of the time in Grinnell you get a frost after April 15 so make sure that you are prepared to protect your centaurea if you have a late frost.

USDA Zone Info for Grinnell

Here is the info for USDA Zone 5a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-20°F
Highest Expected Low	-15°F

This means that on a really cold year, the coldest it will get is -20°F. On most years you should be prepared to experience lows near -15°F.

Plants to Grow in Grinnell

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