One of the first steps you take when you are estimating your gardening schedule is find your 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.

A way of figuring out when to plant spearmint is to consult the USDA zone info for Colby.

Planting Calendar for Spearmint

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

Spearmint are one of those plants that can tolerate quite a bit of cold weather which tells us that you can plant them a quite a bit earlier than plants that are more sensitive to the cold.

The earliest that you can plant spearmint in Colby 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 spearmint and expect a good harvest is probably September. Any later than that and your spearmint may not have a chance to grow to maturity. If you are starting your spearmint indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

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

Always keep in mind that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Colby and it can change quite a bit from year to year. Half of the time in Colby you get surprised by a frost after April 15 so always be ready to cover your spearmint if you have one of those late frosts.

USDA Zone Info for Colby

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 Colby

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