Before planting it is a good idea to find your USDA Zone info to figure out 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.

The USDA zone info for Hillsboro can be reffered to in order to figure out when it's a good idea to plant spearmint.

Planting Calendar for Spearmint

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

Since spearmint are very cold tolerant you can plant them a lot earlier in the year than more sensitive plants.

The earliest that you can plant spearmint in Hillsboro 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. You probably don't want to wait any later than that or else your spearmint may not have a chance to fully mature. If you are starting your spearmint indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

The average date of last frost is April 15 in Hillsboro. In the coldest months of winter you should expect an average low temperature of -10°F.

Since the USDA zone info for Hillsboro is an average the actual date of last frost can change quite a bit from year to year. Half of the time in Hillsboro 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 Hillsboro

Here is the info for USDA Zone 6a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-10°F
Highest Expected Low	-5°F

This means that on a really cold year, the coldest it will get is -10°F. On most years you should be prepared to experience lows near -5°F.

Plants to Grow in Hillsboro

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