Saturday, July 14, 2012

Border Penstemons, P. gloxinioides "Sensation"

Penstemons are pretty much exclusively found in North America, mainly in the western part. Many of the western ones are challenging to grow in the humid and rainy east, but some of the garden strains are easier.  Penstemon gloxinioides "Sensation" is a seed mix which produces a wide variety of colorful plants. P. gloxinioides is a Mexican species (and may be synonymous with P hartwegii, there seems to be some confusion in that I see these "border" penstemons under either name) and thus is not as cold hardy as most of its US brethren, but they grow fast from seed and can be grown as annuals if started early.  I remember growing these years ago when I was a kid.  I don't see them growing in gardens around here, so I had to search to get seed, and as is often the case, Chilterns in the UK was my source. They usually take a beating during winter in NY, often dying but sometimes respouting from the base, but in this extraordinary year, they sailed through the very mild winter with practically no damage.  This allowed them to begin blooming in May, and they are still blooming off and on.  I'm sure if I were to deadhead them they would make even more flowers but I want to get my own seed to try in the future.  Many new buds are forming so I expect another big wave of bloom in a few weeks time in August. 
There are named cultivars of this that are propagated from cutting, I did get a couple of these from Forest Farm and am curious to see how they compare to the seed grown plants. Right now neither of the two plants from FF is in bloom, but I anticipate they will do so in about a month or so.

Diverse Dianthus in the Garden

Dianthus deltoides

Dianthus deltoides

Bicolored with picotee

Semidouble dianthus x allwoodii

Fringed flowers

Cool pattern!

Fringed pure white

Simple pink bicolor

Another cool patterned flower

Simple pink bicolor closeup

Variety of x allwoodii seedlings

Fringes and rings

Neat habit
Dianthus is a rather large genus with lots of attractive species (see the recent post on (mostly) species on Panayoti's blog: and innumerable hybrids.  The genus ranges across Eurasia and, unbeknownst to many, has a decent number of South African representatives as well. In my school garden they do well in the sloped garden, as they prefer good drainage and plenty of sun.  Some plants I purchased from various mailorder nurseries but most of them are seed grown, either from NARGS seed, seeds from the UK, or seeds of my original plants.  Many of the ones shown above grew from excess seed I cast out onto the slope a couple of years ago.  Most dianthus cvs are prolific seed producers so there is plenty of seed to experiment with (and they will resow around the parent plants if allowed). Its also good to keep new ones coming along as the individual plants can be shortlived perennials, especially in a bad year with excessive rains and heat at the same time.  Some are very fragrant. Should you desire, favored clones can be propagated quite readily from stem cuttings.  Most of them bloom en mass in mid to late May here in NY, but many will keep producing a few flowers here and there for the rest of the growing season. 
The first two photos are cultivars of Dianthus deltoides, these form low mats of deep green minute foliage and can spread slowly. Apparently they have naturalized in some places in the US, but this is not a scary invasive species at all.  The seeds are smaller than the hybrid dianthus and they flower mostly in spring but will make more flowers later on, especially if deadheaded.  The remaining photos are of Dianthus hybrids, probably/mainly of the x allwoodii type.  They have several species in this bloodline and this complex gene makeup results in a very varied group of plants.  Leaves can be varying degrees of blue green to grey green to simply green and the flowers range from white to red, singles to doubles, and come in all kinds of shapes and color patterns.
Seed is both easy to collect and easy to start.  Germination is straightforward, no cold period needed, and some plants may produce a few flowers their first year if started early.  Once you have a colony of them going, its easy to collect seed and even broadcast it to get more plants.