related plantS Penstemon digitalis
(zones 3–8), foxglove penstemon,
should be deadheaded to a lateral leaf
after flowering and then cut down to
new basal growth as old stems decline.
This species is longer lived, hardier,
and more tolerant of damp soil than P.
barbatus. It is the species of choice for
the lower-maintenance garden.
Penstemon digitalis ‘Husker’s Red’(2–3
ft.) has spikes of white blossoms over
outstanding purple-red foliage. Cut it
down to new basal growth if the old
foliage fades in late summer or
autumn. ‘Dark Towers’ is similar to
‘Husker’s Red’ and comes from the
same breeder, Dr. Dale Lindgren of the
University of Nebraska, but it is a
hybrid plant. ‘Dark Towers’ has deeper
burgundy foliage, pale pink flowers,
and a taller habit than ‘Husker’s Red’.
Dr. Lindgren also developed the
‘Prairie’ series of penstemons, which
do well in the Midwest, where most
penstemons don’t thrive. I’ve had
great success with ‘Prairie Twilight’.
A group of hybrid penstemons that
goes by the name Penstemon ×mexicali
includes some popular and relatively
adaptable selections like ‘Pike’s Peak
Purple’ (grape purple) and ‘Red Rocks’
(pink). They are more cold hardy and
more forgiving than many other
penstemons, but still need excellent
drainage, especially in winter. They
bloom best in spring and fall, when the
weather is cool.
Penstemon ‘Red Riding Hood’ has
bright coral-red blooms on 2-ft. plants
and is hardy in zones 5–8. Seven
selections make up the ‘Riding Hood’
series, in colors from red to pink to
lavender to blue.Penstemon barbatus