One of the best tools that you have as gardeners to help us determine 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.

It's a good idea to estimate when it's possible to plant spearmint by referring to the USDA zone info for Alton.

Planting Calendar for Spearmint

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

Spearmint do ok in cold weather which means that you can plant them earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant spearmint in Alton 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. If you wait any later than that and your spearmint may not have a chance to really do well. You can get started a little bit earlier by starting your spearmint indoors.

Last Frost Date

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

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

USDA Zone Info for Alton

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 Alton

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