The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. 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 Forest Lake should be reffered to in order to figure out when it's possible to plant penstemon.

Planting Calendar for Penstemon

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

You can plant penstemon a bit earlier in the year because they are moderately cold tolerant.

The earliest that you can plant penstemon in Forest Lake 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 grow to maturity. You can get started a few weeks earlier by starting your penstemon indoors.

Last Frost Date

The average date of last frost is May 15 in Forest Lake. In the coldest months of winter you should expect an average low temperature of -25°F.

Since the USDA zone info for Forest Lake is just an average the actual date of last frost changes from year to year. Half of the time in Forest Lake it frosts late in the year after May 15 so make sure that you are ready to cover your penstemon if you have a surprise late frost.

USDA Zone Info for Forest Lake

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 Forest Lake

You may be interested in your other planting guides for Forest Lake.