Before planting it is a good idea to find your USDA Zone info to determine 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.

One way of estimating when it's possible to plant centaurea is to examine the USDA zone info for Walla Walla.

Planting Calendar for Centaurea

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

Since centaurea do well in moderate cold you can plant them a little earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant centaurea in Walla Walla 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. If you wait any later than that and your centaurea may not have a chance to grow to maturity. If you are starting your centaurea indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

In Walla Walla the average date of last frost happens on April 15. In the coldest months of winter you should expect an average low temperature of 0°F.

Just be sure to remember that USDA zone info for Walla Walla is just an average and the actual date of last frost is different every year. Since half of the time in Walla Walla it frosts late in the year after April 15 be ready to cover your centaurea if you have a surprise late frost.

USDA Zone Info for Walla Walla

Here is the info for USDA Zone 7a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	0°F
Highest Expected Low	5°F

This means that on a really cold year, the coldest it will get is 0°F. On most years you should be prepared to experience lows near 5°F.

Plants to Grow in Walla Walla

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