One of the best tools that you have as gardeners to help us determine your gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The best time to plant yarrow in Green River 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 Green River is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant yarrow and expect a good harvest is probably August. If you wait 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 couple of weeks earlier.

Last Frost Date

The average date of last frost is May 15 in Green River. In the coldest months of winter you should expect an average low temperature of -25°F.

Since the USDA zone info for Green River is an average the actual date of last frost changes from year to year. Since half of the time in Green River there is a last frost after May 15 be ready to protect your yarrow if you have one of those late frosts.

USDA Zone Info for Green River

Here is the info for USDA Zone 4b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-25°F
Highest Expected Low	-20°F

This means that on a really cold year, the coldest it will get is -25°F. On most years you should be prepared to experience lows near -20°F.

Plants to Grow in Green River

You may be interested in your other planting guides for Green River.