One of the best tools that you have as gardeners to help us figure out your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

You should be able to figure out when it's possible to plant yarrow by looking at the USDA zone info for Warrenton.

Planting Calendar for Yarrow

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

Yarrow do well in a bit of cold which tells us that you can plant them much earlier in the year than more sensitive plants.

The earliest that you can plant yarrow in Warrenton is January. However, you really should wait until February if you don't want to take any chances.

The last month that you can plant yarrow and expect a good harvest is probably October. Any later than that and your yarrow may not have a chance to fully mature. If you are starting your yarrow indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

The average date of last frost is February 15 in Warrenton. You can expect an average low temperature of 20°F in the coldest months of winter.

Since the USDA zone info for Warrenton is just an average the actual date of last frost can change quite a bit from year to year. Since half of the time in Warrenton you get a frost after February 15 be ready to cover your yarrow if you have one of those late frosts.

USDA Zone Info for Warrenton

Here is the info for USDA Zone 9a.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	20°F
Highest Expected Low	25°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 25°F.

Plants to Grow in Warrenton

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