Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

By referring to the USDA zone info for Andover you should be able to estimate when it's a good idea 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.

Penstemon do ok in a little bit of cold which means that you can plant them a little earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant penstemon in Andover 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 really do well. 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 April 15 in Andover. In the coldest months of winter you should expect an average low temperature of -5°F.

Since the USDA zone info for Andover is just an average the actual date of last frost can change quite a bit from year to year. Half of the time in Andover you get surprised by a frost after April 15 so make sure that you are ready to protect your penstemon if you have a late frost.

USDA Zone Info for Andover

Here is the info for USDA Zone 6b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-5°F
Highest Expected Low	0°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 0°F.

Plants to Grow in Andover

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