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.

You can figure out when it's possible to plant pentas in Alton by looking at the USDA zone info.

Planting Calendar for Pentas

Frost tolerance for pentas:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

Pentas are not cold tolerant which means that it is important to wait until it warms up after the last frost before you can plant them.

The earliest that you can plant pentas 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 pentas and expect a good harvest is probably August. You probably don't want to wait any later than that or else your pentas may not have a chance to grow to maturity. You can get started a little bit earlier by starting your pentas indoors.

Last Frost Date

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

Just be sure to remember that USDA zone info for Alton is just an average and the actual date of last frost will vary from year to year. Since half of the time in Alton there is a last frost after April 15 be ready to protect your pentas 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.