One of the first steps you take when you are estimating 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.

The USDA zone info for Boulder can be reffered to in order to figure out when it's possible to plant monarda.

Planting Calendar for Monarda

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

You can plant monarda slightly earlier in the year because they do ok in moderate cold.

The earliest that you can plant monarda 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 monarda and expect a good harvest is probably August. If you wait any later than that and your monarda may not have a chance to fully mature. Starting your monarda indoors is a great way to get them started a few weeks earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on April 15 in Boulder. You can expect an average low temperature of -15°F in the coldest months of winter.

Since the USDA zone info for Boulder is not always accurate the actual date of last frost is different every year. Half of the time in Boulder you get a frost after April 15 so make sure that you are prepared to cover your monarda in the event of a surprise late frost.

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.