The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

You should be able to determine when you can plant penstemon by using the USDA zone info for Riverdale.

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 moderately cold tolerant you can plant them just a bit earlier in the year than other frost tender plants.

The earliest that you can plant penstemon in Riverdale 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. Any later than that and your penstemon may not have a chance to fully mature. You can get started a few weeks earlier by starting your penstemon indoors.

Last Frost Date

In Riverdale the average date of last frost happens on March 15. In the coldest months of winter you can expect an average low temperature of 10°F.

Always keep in mind that USDA zone info for Riverdale is not always accurate and the actual date of last frost will vary from year to year. Since half of the time in Riverdale last frost occurs after March 15 be ready to cover your penstemon in the event of one of those late frosts.

USDA Zone Info for Riverdale

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 Riverdale

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