Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The USDA zone info for Marshall should be used to determine when you can plant penstemon.

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 one of those plants that can tolerate a little bit of cold weather you can plant them a little bit earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant penstemon in Marshall 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. If you wait any later than that and your penstemon may not have a chance to fully mature. You can get started a few weeks earlier by starting your penstemon indoors.

Last Frost Date

On average the last frost is on May 15 in Marshall. In the coldest months of winter you can expect an average low temperature of -25°F.

Always keep in mind that USDA zone info for Marshall is an average and the actual date of last frost changes from year to year. Half of the time in Marshall you get a frost after May 15 so make sure that you are ready to protect your penstemon in the event of a surprise late frost.

USDA Zone Info for Marshall

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 Marshall

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