One of the best tools that you have as gardeners to help us determine your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

One way of making a decision about when to plant penstemon is to refer to the USDA zone info for Deerfield.

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 just a bit earlier in the year because they do well in moderate cold.

The earliest that you can plant penstemon in Deerfield 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. You probably don't want to wait any later than that or else your penstemon may not have a chance to fully mature. If you are starting your penstemon indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on April 15 in Deerfield. In the coldest months of winter you should expect an average low temperature of -15°F.

Since the USDA zone info for Deerfield is just an average the actual date of last frost can change quite a bit from year to year. Half of the time in Deerfield you get surprised by a frost after April 15 so just be sure to be ready to cover your penstemon in the event of a late frost.

USDA Zone Info for Deerfield

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 Deerfield

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