Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

It's a good idea to figure out when it's possible to plant achillea by looking at the USDA zone info for Colby.

Planting Calendar for Achillea

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

Achillea are one of those plants that can tolerate quite a bit of cold weather which tells us that you can get them planted much earlier than other frost tender plants.

The earliest that you can plant achillea in Colby 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 achillea and expect a good harvest is probably September. You probably don't want to wait any later than that or else your achillea may not have a chance to really do well. If you are starting your achillea indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

On average the last frost has passed is on April 15 in Colby. It might get as low as -15°F during the coldest months of winter.

Since the USDA zone info for Colby is an average the actual date of last frost changes from year to year. Since half of the time in Colby you get surprised by a frost after April 15 be ready to cover your achillea if you have a late frost.

USDA Zone Info for Colby

Here is the info for USDA Zone 5b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-15°F
Highest Expected Low	-10°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 -10°F.

Plants to Grow in Colby

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