One of the first steps you take when you are estimating your gardening schedule is find your 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.

By using the USDA zone info for Seward you should be able to estimate when you can 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 are moderately cold tolerant which tells us that you can start planting them earlier than other plants that might not handle the cold.

The earliest that you can plant penstemon in Seward 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. If you are starting your penstemon indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on April 15 in Seward. It might get as low as -15°F during the coldest months of winter.

Since the USDA zone info for Seward is just an average the actual date of last frost can change quite a bit from year to year. Half of the time in Seward it frosts late in the year after April 15 so just be sure to be ready to cover your penstemon in the event of a surprise late frost.

USDA Zone Info for Seward

Here is the info for USDA Zone 5b.

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

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

Plants to Grow in Seward

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