The USDA Zone info is a great tool for gardeners to help us figure out your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A common way of making a decision about when it's possible to plant yarrow is to examine the USDA zone info for Walla Walla.

Planting Calendar for Yarrow

Frost tolerance for yarrow:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Since yarrow are very cold tolerant you can plant them much earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant yarrow 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 yarrow and expect a good harvest is probably September. If you wait any later than that and your yarrow may not have a chance to grow to maturity. You can get started a couple of weeks earlier by starting your yarrow indoors.

Last Frost Date

The average date of last frost is April 15 in Walla Walla. It might get as low as 0°F during the coldest months of winter.

Remember that the actual date of last frost is not always accurate because it is based on the USDA zone info for Walla Walla and it can change quite a bit from year to year. Half of the time in Walla Walla you get a frost after April 15 so always be ready to cover your yarrow in the event of a 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.