Penstemon — beard tongue
Penstemon — a genus of well over two hundred species,
including annuals, biennials, perennials, and subshrubs, all native to North and
Central America. They are classified in the plantain family (plantaginaceae), at least that's what
the latest version of GRIN says.
They used to be classified in scrophulariaceae, but along with the
snapdragons (antirrhinum) and foxgloves (digitalis), they've
been shipped out. Not that it matters too much which botanical company they
hold - the genus is big enough to hold its own.
The genus name derives from the Greek words πεντα
(penta: five) and στημων (stemon: thread),
referring to the five stamens within their flowers (one of which is
sterile). The common name describes the fuzzy feature on the bottom lips of
the flowers, not unlike the beards in bearded irises.
As wildflowers, penstemons are widely distributed across North America,
making their home in habitats ranging from plains to mountain areas. While
some species require more moisture than others, all appreciate well-drained
soil, and many insist on it. Full sun is best for most, although some do fine
in part shade. Luckily for me, the majority are hardy in our garden in USDA
zone 6 (and many can tolerate quite a bit colder climates).
A few species have been long-lived for us (P. hirsutus var. pygmaeus
and P. pinifolius, for example), but more commonly the plants fade away
after a few years, and must be replenished periodically. We've had quite a
number of generations of P. strictus by now - but they're nice enough
to warrant the effort.
All of my beard tongue multiplication efforts proceed via seed. I imagine
most species can be divided without too much trouble, but for some reason
I've never tried. Penstemons aren't always easy to start from seed -
germination requirements vary widely from species to species, many requiring
cold conditioning and/or light, and often not responding even when
"by-the-book" conditions are provided. An extensive overview of penstemon
germination requirements (or suggestions) is given at a
few pages in Tom Clothier's Garden Walk and Talk website.
My own experience is that some species are really quite easy to establish
by seed, while others always seem to give trouble during germination, and/or
resent the conditions I provide during growing-on in the basement. Still, I
germinated enough of 'm that I have some purdy pictures to show on this
page. I provide detailed records of my germination attempts on many of the
individual species portraits linked from this page. That's only for the ones
I've successfully grown, though - for species I never managed to germinate
and grow on, I won't bother you with the negative results.
Penstemon seeds are angular particles, usually easily extracted from spent
flowers. Their color ranges from tan to black. Seed stays viable for a year or
two, but loses viability in subsequent years. Interestingly, a penstemon-fanatic
seed trading partner told me that very fresh seed often does not germinate well,
or has additional germination requirements (cold or light) when fresh, which
are no longer required with stored seed. So perhaps year-old seed is best.
Beard tongues in the garden
None of the penstemons we grow rise above three feet, and many of them are
a good bit shorter than that. Somehow, I don't see them as lending themselves
to mass plantings (although I may be wrong!), so in our garden they serve as
accents - punctuation marks between plants of larger scales or bigger bulk.
Many have an upright, somewhat sparse or lanky habit, working effectively
when weaving in with other plants with similar habits but different overall
appearance. The bushier ones tend also to be shorter, making good front-of-the-border
plants. This of course goes for the truly diminutive P. hirsutus var. pygmaeus,
but also holds for P. smallii.
The best place for many penstemons is probably not in a traditional border,
but in the rock garden. That's where our P. pinifolius lives, but
would also be a better station for others we've grown and lost - especially
P. heterophyllus, which always seemed a bit lost in a regular garden
Penstemon foliage varies quite a bit in shape, color, and habit. Leaves
are oppositely arranged, and as far as I know always undivided. Extremes
vary from needle-shaped leaves to rounded and lax, from glossy to mat, from
toothed to entire. A few examples are shown below.
|P. cobaea: glossy, mid-green, slightly
serrated leaves, sparsely arranged along stalk
||P. hirsutus var. pygmaeus: dense mat of dark-green,
||P. x mexicali: bright green serrated
strap-shaped leaves, neatly arranged along stems
|P. pinifolius: as the species name
suggests, this one has needle-like leaves, arranged in bunches like pines.
||This P. digitalis is purportedly 'Husker
Red' - probably a seed strain, since its burgundy color doesn't hold up well
as it should.
||P. heterophyllus has smooth-edged,
strappy gray-green leaves.
|Classic opposite arrangement of serrated leaves on
||Substantial blue-green leaves clasping the stem on
Leaves are all good and well, but I don't know anyone who actually grows
penstemons for their foliage. This bunch packs its primary punch in bloom!
Although the basic features of the flowers in the genus are the same, there's
plenty of variety:
|P. cobaea has the largest flowers of
our penstemons; it's almost gaudy!
||P. heterophyllus sports clear blue
||P. hirsutus makes cheery flowers with
soft lavender exteriors and white interior. As the species name suggests, they
||Its diminutive cousin P. hirsutus var. pygmaeus
looks quite a bit different; the first one we grew was shiny purple on the
outside with more of a flattened shape.
||P. whippleanus goes for a sleek plum
purple look, with stripes inside
|P. smallii's white-hairy flowers are
borne in great numbers
||P. pinifolius's masses of lipstick-red
thin tubes put the neighbor's sportscar to shame.
||P. triflorus returns to the bold
pink-spectrum flowers, albeit a bit more refined than cobaea.
||P. digitalis shows off charming rounded
flowers by the bunch
||P. cardinalis ssp. cardinalis features
striking carmine-red tubular flowers with a hint of a yellow beard.
|This P. x mexicali 'Red Rocks' has
showy, but smaller flowers.
||P. strictus is another blue one (I
particularly like the blues). Smooth texture and conspicuous stamens.
||P. wrightii has slightly downy flowers,
uniformly colored in a very pleasing shade of deep pink.
Most penstemons in our garden are squarely in the deciduous corner - not
much to look at during the cold months. But a few species continue to provide
interest through winter. The two photos below show examples:
The leaves of P. hirsutus var. pygmaeus, at left, go limp but turn a
bright purple color (this photo was taken in February). As for P. pinifolius,
it maintains its needles almost as well as real pines - although it tends to
look a bit messy with the autumn leaves it collects.
A seed trader this year tempted me to start a whole bunch of new penstemon
species. Although I'm sure not all of them will germinate, and of those that
do not all will survive their first year, I still hope to have plenty more
varieties to add to this page soon. Stay tuned!
A useful link collection is provided in the Open Directory Project's
. You'll find an extensive list of species with identification information
on the website of the American Penstemon Society.
Visitors to this page have left the following comments
|firstname.lastname@example.org||Sep 02, 2008||Nice information|
|Barbara Lewis, American Penstemon Societ||Jan 18, 2009||Excellent website with good information and outstanding photos of penstemons. Thanks. |
|Pat Ross||Feb 11, 2009||Thank you for the excellent photos and information. I am envious! Your penstemons are beautiful!!!!! And your comments are priceless!|
|Pat Redler||Jul 24, 2009||Your pictures are gorgeous! I have wanted a red penstemon for a long time, but guess they are hard to find. I think one of my gardening catalogs had one as a plant. Will order for sure next year.|
|Mona||Aug 20, 2009||Thanks! I am new to seed saving and was wondering how to propagate the goodies I bought this past spring. really appreciate the info! happy planting...|
|sheila pocklington||Mar 07, 2012||I have grown some penstemon from seed do I pinch out the middle of these plants|
I would not pinch any parts of the plants until they have a season of growth on them – after they start growth in their second year you could prune the shrubbier penstemons so that they grow in a way that pleases you.
|margaret||Apr 03, 2012||When is the correct time to cut back penstemons?|
It depends. Some penstemons are fully herbaceous/deciduous, others maintain an evergreen rosette, while still others are shrubby. For all of them, you can cut down spent flower stalks once they are no longer attractive. The shrubby ones can use a tidying up in early spring, once new growth starts to show. Other than that, there aren't many seasonal maintenance requirements.
|LouRene Fitzsimmons||Aug 09, 2013||Yours is a wonderful website. Great information. Your personal experience is invaluable. My question is do you use everyday seed starting medium that one purchases from nurseries or something special? I think the seeds a friend is giving me are either P.Heterophyllus or P Laetus, but not sure. Thank you so much for this great website.|
I use common soilless potting mixes such as Promix. For seeds, I prefer to have at least a top layer of a finely milled product (such as Promix PgX), but the standard stuff pretty much will work. Most penstemons appreciate good drainage, so it may be beneficial to use a gritty mix – but I've not typically gone to that trouble. Of course that may explain why my success rate with penstemons is only so-so.
|J Ladd||Apr 10, 2014||tell Pat Redler who wants red, to try "hot lips"|
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May 27, 2015