Growing Penstemon from seed in Massachusetts

Submitted by sf2bos2prov on Sun, 10/21/2018 - 15:02

Hello, I'm in eastern Massachusetts in zone 6b, new to NARGS, and have recently fallen in love with Penstemon even though I know most species are native to the west.  I have a regular flower bed (not a rock garden and not amended with sand or gravel) that I'd like to give over to Penstemon next year.  I'd like to grow several different species from seed. I'll of course try the eastern US natives but would also like to try some of the others that just MIGHT be able to grow here in our wet summers and winters and fairly fertile soil.  I'll probably start the seeds in pots outdoors in, say late November, maybe with window screening on top, and leave them outside all winter to get their stratification.  My question: in the spring when I have seedlings, should I plant those in the ground then, or should I let them grow in the pots through the summer and plant the larger seedlings in early fall?

Or, what about the idea of direct-seeding right in the garden in late November? 

Thanks for any advice.


Submitted by RickR on Sun, 10/21/2018 - 21:40

Welcome to NARGS!

I would plant in spring after at least two or three sets of true leaves are mature, depending on the total size of the seedling.  P. hirsutus, P.h. var. pygmaea, P. cobaea  ought to do well.  P. grandiflorus is your best bet of the blue glabrous leaf types.  If you can get a hold of P. gracilis or P. pallidus, they might do well, too.  As you already realize, dryland plants have an especially hard time in moist, fertile soil.  They will likely grow out of character, be floppy, and winter survival is questionable.  Any western species must have full sun, and if you can plant on a mound the soil to help it dry out faster, that would be good.

Submitted by sf2bos2prov on Fri, 10/26/2018 - 18:40

In reply to by RickR

Thanks kindly for this.  I now have seeds for all the species you mention except P. hirsutus var. pygmaea and will give them a try.  Of these, I might winter-sow half in translucent plastic gallon jugs and direct-sow the other half right in the garden in a month or so, and then compare what happens in the spring.

btw, I know that glabrous means 'smooth', but are 'blue glabrous leaf types' a well-known category of Penstemon?  I'm slowly learning about subgenus, section and subsection for Penstemon- do blue glabrous leaf types correspond to one of these categories?

Submitted by RickR on Fri, 10/26/2018 - 21:01

I must say that I am not that well versed in Penstemon, but I do have Bob Nold's book, Penstemons, as well as the Penstemon key by the Lodewicks.  P. grandiflorus belongs to section Coerulei, but another well known "blue", P. palmeri, is in section Peltanthera.  Both are subgenus penstemon, but I really can't answer your question.  Actually, I kinda assumed all the blue glabrous penstemon would be closely related, but I guess not.  Incidentally, I did grow a few P. palmeri to flowering, but they did not return the next year, nor did they reseed.  My P. grandiflorus population is self sustaining for 20 years, and seeds into my lawn, too.

Penstemon palmeri



Penstemon grandiflorus


Your grandiflorus are beautiful. 20 years is incredible. I'm guessing I may not have such luck given our 44" average rainfall here in Boston. But I'm going to try. 

I'm guessing my climate is not hospitable to P. palmerii which I believe needs much more arid conditions.  I'd love to grow it as I understand it's fragrant.  

Submitted by RickR on Sat, 10/27/2018 - 22:17

Sorry, blue flowers completely slipped my mind!  No, I'm talking a bout the glabrous blue tinted, succulent-like foliage.

In the wild here in Minnesota, P. grandiflorus usually grows in pure, deep sand or rock crevices.  pH doesn't seem to be a factor, as I have seen it growing in acid sand, and limestone crevices.  Mine are grown from local seed, and actually grow in fairly rich clay based soil, but in the driest part of my yard, full sun (of course), and no watering.  The pic is a little deceiving, as it looks very lush (and it was, comparatively speaking, that year).  If you were to see a pic from above, you would realize that plants are sparsely placed, allowing a lot of soil exposure to the sun's heat that dries it more quickly.

ok, thanks.  I didn’t realize there are penstemon species with that kind of foliage.

I see your average annual precipitation is 24” compared to our 44” here in Boston. I wonder how that’ll affect what penstemons I can and can’t grow.

Submitted by RickR on Mon, 10/29/2018 - 17:28

When I grew P. palmeri from seed, I transplanted most of the seedlings in the clay based, full sun, no water situation I previously mentioned.  But I transplanted one in better draining, but richer soil in three-quarter sun, with some watering.  The latter grew twice as fast and ultimately twice as big, layed almost prostrate but still above the soil, and died that winter.  The former bunch grew vertically, and slower, and went on to bloom in the next year or two.

And FYI, I fertilize my lawn about once every four years.




Submitted by Muggli on Wed, 10/31/2018 - 12:00

Hello, I live in eastern Minnesota and we receive approximately 30 inches of rain per year.  I've been following your discussion on suitable penstemon species for your conditions.  Perhaps Penstemon serrulatus the cascade penstemon would work for you.  I have had a plant of this species for 4 or 5 years growing in my native soil with no amendments.  The only issue I have is winter damage due to our severe winters but your zone is 2 warmer.  This species originates from the west slopes of the Cascade mountains so it is used to wetter conditions than many western members of this genus. You might want to consider this for your rock gardens - I think it is quite attractive.

Thanks for this, Muggli.  I'll look for seeds for that one.  I just looked up P. serrulatus in my copy of Growing Penstemons by Lindgren and Wilde and it looks interesting. I'm glad to know there are a significant number of Penstemon species that are native to the Pacific Northwest and therefore have very different environmental needs than what I think as the more common Penstemon species that grow in more arid regions.

btw, the description in the book mentions "Often there are sports in white, pink and orchid."  I'd never heard the term before in botany so I just read the article on Wikipedia here.  Are bud sports common in the Penstemon world?

Submitted by Muggli on Thu, 11/01/2018 - 07:14

Sorry, I don't know how common bud sports are within the genus.  Many cultivars in other genera were selected from sports.