The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

In Johnston you can figure out when you can 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.

Achillea tend to make it in a bit of cold which tells us that you can plant them earlier in the year than other plants that might not handle the cold.

The earliest that you can plant achillea in Johnston 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. If you are starting your achillea indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

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

Since the USDA zone info for Johnston is an average the actual date of last frost is different every year. Since half of the time in Johnston it frosts late in the year after April 15 be ready to cover your achillea in the event of a late frost.

USDA Zone Info for Johnston

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 Johnston

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