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.

The best time to plant yarrow in Thomson should be figured out by referring to the USDA zone info.

Planting Calendar for Yarrow

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

You can plant yarrow quite a bit earlier in the year because they do well in cold.

The earliest that you can plant yarrow in Thomson 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 fully mature. You can get started a couple of weeks earlier by starting your yarrow indoors.

Last Frost Date

On average all chance of frost has passed is on March 15 in Thomson. It might get as low as 10°F during the coldest months of winter.

It's important to remember that the actual date of last frost is just an average because it is based on the USDA zone info for Thomson and it changes from year to year. Since half of the time in Thomson you get a frost after March 15 be ready to cover your yarrow in the event of one of those late frosts.

USDA Zone Info for Thomson

Here is the info for USDA Zone 8a.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	10°F
Highest Expected Low	15°F

This means that on a really cold year, the coldest it will get is 10°F. On most years you should be prepared to experience lows near 15°F.

Plants to Grow in Thomson

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