One of the best tools that you have as gardeners to help us figure out your gardening schedule is the 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 Alton should be read to figure out when to plant basil.

Planting Calendar for Basil

Frost tolerance for basil:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

It's a bad idea to plant basil until after the last frost has passed because they do not do well in cold weather.

The earliest that you can plant basil in Alton is April. However, you really should wait until May if you don't want to take any chances.

The last month that you can plant basil and expect a good harvest is probably August. Any later than that and your basil may not have a chance to fully mature. You can get started a few weeks earlier by starting your basil indoors.

Last Frost Date

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

Just be sure to remember that USDA zone info for Alton may not be accurate from year to year and the actual date of last frost can change quite a bit from year to year. Since half of the time in Alton it frosts late in the year after April 15 be ready to cover your basil 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.