The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

You should be able to determine when it's possible to plant penstemon by using the USDA zone info for Lewistown.

Planting Calendar for Penstemon

Frost tolerance for penstemon:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Since penstemon do well in moderate cold you can plant them just a bit earlier in the year than more sensitive plants.

The earliest that you can plant penstemon in Lewistown 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 penstemon and expect a good harvest is probably September. If you wait any later than that and your penstemon may not have a chance to really do well. Starting your penstemon indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

The average date of last frost is April 15 in Lewistown. You should expect an average low temperature of -5°F in the coldest months of winter.

Since the USDA zone info for Lewistown is an average the actual date of last frost changes from year to year. Since half of the time in Lewistown you get surprised by a frost after April 15 be ready to protect your penstemon if you have one of those late frosts.

USDA Zone Info for Lewistown

Here is the info for USDA Zone 6b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-5°F
Highest Expected Low	0°F

This means that on a really cold year, the coldest it will get is -5°F. On most years you should be prepared to experience lows near 0°F.

Plants to Grow in Lewistown

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