Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

One way of figuring out when it's the best time to plant yarrow is to examine the USDA zone info for Delta.

Planting Calendar for Yarrow

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

Since yarrow are one of those plants that can tolerate quite a bit of cold weather you can plant them quite a bit earlier in the year than other plants that might not handle the cold.

The earliest that you can plant yarrow in Delta 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. Any later than that and your yarrow may not have a chance to really do well. Starting your yarrow indoors is a great way to get them started a few weeks earlier.

Last Frost Date

On average the last frost has passed is on April 15 in Delta. You can expect an average low temperature of -5°F in the coldest months of winter.

Since the USDA zone info for Delta is just an average the actual date of last frost can change quite a bit from year to year. Half of the time in Delta there is a last frost after April 15 so always be ready to cover your yarrow in the event of a surprise late frost.

USDA Zone Info for Delta

Here is the info for USDA Zone 6b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-5°F
Highest Expected Low	0°F

This means that on a really cold year, the coldest it will get is -5°F. On most years you should be prepared to experience lows near 0°F.

Plants to Grow in Delta

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