One of the first steps you take when you are determining your gardening schedule is find your 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 estimating when to plant penstemon is to look at the USDA zone info for Sullivan.

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 earlier in the year than more sensitive plants.

The earliest that you can plant penstemon in Sullivan 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. If you wait 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 April 15 in Sullivan. In the coldest months of winter you should expect an average low temperature of 5°F.

Since the USDA zone info for Sullivan is an average the actual date of last frost is different every year. Half of the time in Sullivan you get surprised by a frost after April 15 so make sure that you are ready to cover your penstemon in the event of a late frost.

USDA Zone Info for Sullivan

Here is the info for USDA Zone 7b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	5°F
Highest Expected Low	10°F

This means that on a really cold year, the coldest it will get is 5°F. On most years you should be prepared to experience lows near 10°F.

Plants to Grow in Sullivan

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