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.

In Rock Springs you can figure out when to plant achillea by reviewing the USDA zone info.

Planting Calendar for Achillea

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

You can plant achillea a lot earlier in the year because they are very cold tolerant.

The earliest that you can plant achillea in Rock Springs 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. If you wait any later than that and your achillea may not have a chance to really do well. Starting your achillea indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

On average the last frost has passed is on April 15 in Rock Springs. You can expect an average low temperature of -20°F in the coldest months of winter.

Just be sure to remember that USDA zone info for Rock Springs is an average and the actual date of last frost is different every year. Half of the time in Rock Springs it frosts late in the year after April 15 so make sure that you are ready to protect your achillea if you have one of those late frosts.

USDA Zone Info for Rock Springs

Here is the info for USDA Zone 5a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-20°F
Highest Expected Low	-15°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 -15°F.

Plants to Grow in Rock Springs

You may be interested in your other planting guides for Rock Springs.