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

The earliest that you can plant penstemon in Holmen should be figured out by looking at the USDA zone info.

Planting Calendar for Penstemon

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

Penstemon do well in moderate cold which tells us that you can start planting them earlier than more sensitive plants.

The earliest that you can plant penstemon in Holmen 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 penstemon and expect a good harvest is probably August. Any later than that and your penstemon may not have a chance to fully mature. Starting your penstemon indoors is a great way to get them started a little bit earlier.

Last Frost Date

On average the last frost is on May 15 in Holmen. It might get as low as -25°F during the coldest months of winter.

Keep in mind that the actual date of last frost is just an average because it is based on the USDA zone info for Holmen and it changes from year to year. Since half of the time in Holmen you get a frost after May 15 be ready to protect your penstemon if you have a surprise late frost.

USDA Zone Info for Holmen

Here is the info for USDA Zone 4b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-25°F
Highest Expected Low	-20°F

This means that on a really cold year, the coldest it will get is -25°F. On most years you should be prepared to experience lows near -20°F.

Plants to Grow in Holmen

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