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 USDA zone info for Alton should be looked at to estimate when it's possible to plant tarragon.

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.

Tarragon are one of those plants that can tolerate a tiny bit of cold weather which means that you can plant them slightly earlier than plants that are more sensitive to the cold.

The earliest that you can plant tarragon in Alton 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 grow to maturity. If you are starting your tarragon indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

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

Since the USDA zone info for Alton is not always accurate the actual date of last frost can change quite a bit from year to year. Since half of the time in Alton there is a last frost after April 15 be ready to protect your tarragon in the event of a late frost.

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.