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

You should be able to estimate when it's a good idea to plant yarrow by reviewing the USDA zone info for Marshalltown.

Planting Calendar for Yarrow

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

Yarrow tend to make it in pretty solid cold which means that you can plant them earlier in the year than other frost tender plants.

The earliest that you can plant yarrow in Marshalltown 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 yarrow and expect a good harvest is probably September. You probably don't want to wait any later than that or else your yarrow may not have a chance to fully mature. You can get started a couple of weeks earlier by starting your yarrow indoors.

Last Frost Date

The average date of last frost is April 15 in Marshalltown. You should expect an average low temperature of -20°F in the coldest months of winter.

It's important to remember that the actual date of last frost is not always accurate because it is based on the USDA zone info for Marshalltown and it changes from year to year. Half of the time in Marshalltown there is a last frost after April 15 so make sure that you are ready to protect your yarrow if you have a surprise late frost.

USDA Zone Info for Marshalltown

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 Marshalltown

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