One of the first steps you take when you are getting a good idea your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

You will be able to figure out when to plant yarrow by using the USDA zone info for Longmont.

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 a lot earlier in the year because they are very cold tolerant.

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

Last Frost Date

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

Remember that USDA zone info for Longmont may not be accurate from year to year and the actual date of last frost is different every year. Half of the time in Longmont there is a last frost after April 15 so make sure that you are prepared to cover your yarrow in the event of a surprise late frost.

USDA Zone Info for Longmont

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 Longmont

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