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.

In Boulder you can determine when it's the best time to plant cilantro by checking out the USDA zone info.

Planting Calendar for Cilantro

Frost tolerance for cilantro:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Cilantro are barely cold tolerant which tells us that you can plant them slightly earlier than other frost tender plants.

The earliest that you can plant cilantro in Boulder is March. However, you really should wait until April if you don't want to take any chances.

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

Last Frost Date

In Boulder the average date of last frost happens on April 15. In the coldest months of winter you can expect an average low temperature of -15°F.

Just be sure to remember that USDA zone info for Boulder is not always accurate and the actual date of last frost is different every year. Half of the time in Boulder you get a frost after April 15 so just be sure to be ready to protect your cilantro in the event of one of those late frosts.

USDA Zone Info for Boulder

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 Boulder

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