One of the best tools that you have as gardeners to help us estimate your gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The earliest that you can plant tarragon in Boulder can be figured out by reviewing the USDA zone info.

Planting Calendar for Tarragon

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

You can plant tarragon just a tiny bit earlier in the year because they are barely cold tolerant.

The earliest that you can plant tarragon 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 tarragon and expect a good harvest is probably August. You probably don't want to wait any later than that or else your tarragon may not have a chance to fully mature. If you are starting your tarragon indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

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

Since the USDA zone info for Boulder may not be accurate from year to year the actual date of last frost is different every year. Half of the time in Boulder last frost occurs after April 15 so always be ready to protect your tarragon 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.