Ask Mr. Smarty Plants

In our Native Plant Database, Penstemon digitalis (talus slope penstemon) is shown growing in one county north of Thayer County on this USDA Plant Profile, so we can be pretty  confident that it belongs where you are growing it, always a first consideration to us at the Lady Bird Johnson Wildflower Center. Your question was dated May 18, and you said your plants were not blooming. Again according to our database, this plant blooms from May to July. What is often not understood about bloom time ranges is that they go from south to north. This plant grows as far south as Texas and as far north as parts of Canada. If it blooms in May here in Texas, it may not be ready to bloom in Nebraska until June. Plants don't have calendars, they grow according to their genetic instructions and the environment in which they find themselves. It has been a hard, cold winter in most of the United States, and we imagine a lot of plants are either late-blooming or might not bloom at all. Furthermore, this is a semi-evergreen (in the South) perennial, with a taproot, which grows from 3 to 6 ft. tall. At 20" it probably simply isn't big enough to bloom yet.

What caused you to decide the plants were too close together? We suggest you read the comments in this Dave's Garden on Penstemon digitalis. They will give you some information on how this plant grows and how easy it is to care for. 

Now, finally for your question about transplanting your Penstemon right now.  Here are the Propagation Instructions on it from our Native Plant Database:

"Propagation Material: Seeds , Softwood Cuttings , Root Division
Description: Division is the easiest method of increase. Separate crowns in fall or early spring. Prune back the foliage of each new division. Propagate also by seed.
Seed Collection: Seeds ripen in fall.
Seed Treatment: Germination is best with cold-moist stratification and light.
Commercially Avail: yes
Maintenance: For a neat appearance, cut bloom stalks once theyve turned brown. Somewhat short-lived, so keep a supply of seed on hand to renew your population."

It is already too late for "early spring" and way too early for "fall" and you will want to divide the crowns before you transplant them. We prescribe patience, and don't start putting fertilizer on them to make them bloom, especially not the high nitrogen fertilizer that you use on the lawn. That will make the leaves nice and green and inhibit blooming.

From our Native Plant Database:

Penstemon digitalis

Penstemon digitalis

Penstemon digitalis

Penstemon digitalis