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

One way of determining when it's a good idea to plant penstemon is to examine the USDA zone info for Alpena.

Planting Calendar for Penstemon

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

Since penstemon are moderately cold tolerant you can plant them a little bit earlier in the year than other plants that might not handle the cold.

The earliest that you can plant penstemon in Alpena 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. Any later than that and your penstemon may not have a chance to grow to maturity. If you are starting your penstemon indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

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

Keep in mind that USDA zone info for Alpena is just an average and the actual date of last frost changes from year to year. Half of the time in Alpena last frost occurs after April 15 so be sure to be ready to protect your penstemon in the event of one of those late frosts.

USDA Zone Info for Alpena

Here is the info for USDA Zone 5b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-15°F
Highest Expected Low	-10°F

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Alpena

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