One of the best tools that you have as gardeners to help us determine your gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

A way of getting a good idea when it's possible to plant penstemon is to look at the USDA zone info for Manassas.

Planting Calendar for Penstemon

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

Penstemon do well in moderate cold which means that you can plant them earlier than plants that are more sensitive to the cold.

The earliest that you can plant penstemon in Manassas 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

The average date of last frost is April 15 in Manassas. In the coldest months of winter you can expect an average low temperature of 0°F.

It's important to remember that USDA zone info for Manassas is not always accurate and the actual date of last frost will vary from year to year. Half of the time in Manassas there is a last frost after April 15 so just be sure to be ready to protect your penstemon if you have a late frost.

USDA Zone Info for Manassas

Here is the info for USDA Zone 7a.

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

This means that on a really cold year, the coldest it will get is 0°F. On most years you should be prepared to experience lows near 5°F.

Plants to Grow in Manassas

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