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 earliest that you can plant yarrow in Zone 1a can be estimated 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 much earlier in the year because they are very cold tolerant.

The earliest that you can plant yarrow in Zone 1a is May. However, you really should wait until June if you don't want to take any chances.

The last month that you can plant yarrow and expect a good harvest is probably July. 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 Zone 1a the average date of last frost happens on June 15. In the coldest months of winter you can expect an average low temperature of -60°F.

Keep in mind that USDA zone info for Zone 1a may not be accurate from year to year and the actual date of last frost will vary from year to year. Since half of the time in Zone 1a you get surprised by a frost after June 15 be ready to protect your yarrow if you have a late frost.

USDA Zone Info for Zone 1a

Here is the info for USDA Zone 1a.

Average Date of Last Frost (spring)	June 15
Average Date of First Frost (fall)	July 15
Lowest Expected Low	-60°F
Highest Expected Low	-55°F

This means that on a really cold year, the coldest it will get is -60°F. On most years you should be prepared to experience lows near -55°F.

Plants to Grow in Zone 1a

You may be interested in your other planting guides for Zone 1a.