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

You will be able to determine when it's the best time to plant yarrow by using the USDA zone info for Hillsboro.

Planting Calendar for Yarrow

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

Yarrow tend to make it in a bit of cold which means that 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 Hillsboro 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. 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

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

Keep in mind that the actual date of last frost is just an average because it is based on the USDA zone info for Hillsboro and it is different every year. Half of the time in Hillsboro you get surprised by a frost after March 15 so always be ready to cover your yarrow if you have a surprise late frost.

USDA Zone Info for Hillsboro

Here is the info for USDA Zone 8b.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	15°F
Highest Expected Low	20°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 20°F.

Plants to Grow in Hillsboro

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