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.

A common way of getting a good idea when it's the best time to plant penstemon is to use the USDA zone info for Irving.

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 Irving 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 grow to maturity. Starting your penstemon indoors is a great way to get them started a few weeks earlier.

Last Frost Date

The average date of last frost is March 15 in Irving. It might get as low as 10°F during the coldest months of winter.

It's important to remember that the actual date of last frost is an average because it is based on the USDA zone info for Irving and it is different every year. Half of the time in Irving you get surprised by a frost after March 15 so just be sure to be ready to cover your penstemon in the event of a late frost.

USDA Zone Info for Irving

Here is the info for USDA Zone 8a.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	10°F
Highest Expected Low	15°F

This means that on a really cold year, the coldest it will get is 10°F. On most years you should be prepared to experience lows near 15°F.

Plants to Grow in Irving

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