One of the first steps you take when you are figuring out 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.

In Umatilla you can figure out when it's the best time to plant centaurea by using the USDA zone info.

Planting Calendar for Centaurea

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

Centaurea are moderately cold tolerant which means that you can plant them a little bit earlier than other frost tender plants.

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

Last Frost Date

In Umatilla the average date of last frost happens on April 15. It might get as low as 5°F during the coldest months of winter.

Keep in mind 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 Umatilla and it can change quite a bit from year to year. Since half of the time in Umatilla last frost occurs after April 15 be ready to cover your centaurea if you have one of those late frosts.

USDA Zone Info for Umatilla

Here is the info for USDA Zone 7b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	5°F
Highest Expected Low	10°F

This means that on a really cold year, the coldest it will get is 5°F. On most years you should be prepared to experience lows near 10°F.

Plants to Grow in Umatilla

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