Penstemons

Several questions spring to mind...

1. What varieties are you growing? Some (I have found to my expense) are bred more as bedding than for long-term plants. Varieties such as P. 'Electric Blue' grow and flower for maybe 2 years if you are lucky and then die off. Ones like P. 'Mrs Winder' are much better and go on for years and years (I have this one - deep dark burgundy coloured flws).

2. Have you got them in sun or shade? Some books say they tolerate partial shade, but I have never found this to be so.

3. Are they getting sufficient water? I grow a few penstemons each year from cuttings to sell and the young plants produce HUGE root systems and dry out their compost v quickly - they need loads of water!

Hope this helps!

I also take cuttings from mine as I am never sure that they will survive until the next year! As Sid says, some grow well, some don't. 'Garnet' is a reliable one, as is 'Geoff Hamilton'. Two I planted last year have completely disappeared - can't remember the name but they were bright pink with white throats. Sorry that last bit isn't helpful! It is easy to take cuttings, and that's the crunch advice. By the way, you aren't cutting them back or deadheading in the autumn, are you? They should be cut back when fresh new growth appears in the spring. Just wondered if that was the problem.

First and foremost Penstemmons enjoy moisture, 2007 Uk summer was absolutely fine especially in May to mid July. Mine are in partial shade, near a pond and in 07 were great but in 06 when conditions were drier and less humid weaker plants did not thrive. So lesson 1. is keep the planted zone moist.
As Spritzhenry says, and like the pruning of Hydrangeas (which are also water loving plants), do not cut them back until new growth commences in mid spring, then cut back to about 4" to 6" above ground level. So lesson 2, do not prune/cut back to soon.
Penstemmons are susceptible to combined hard (-5C) air and ground frosts which occur more often in the Uk than the weather folk give credit. To help allay the affects of these place a 2" mulch of leaf mould around the basal area of your Penstemmon patch ensuring that each plant has a good 12" diameter of leaf mould. Lesson 3. Try to keep the basal parts of the plants snug with a suitable depth of mulch material which in the spring will also help water retention. Soil in herbaceous borders becomes exhausted and occassionally needs enriching, during the spring as new growth is about to come forth (or is due) work in a multi purpose balanced granular fertiliser eg Growmore. Lesson 4 remember to feed all herbaceous plants in the spring with a suitable general slow release fertiliser, and supplement on impoverished soils with summer liquid feeds.
Footnote: The spring prunings/ cut offs, which might be in leaf, should not be immediately discarded. Select the healthiest stems reduce them to about 3" to 4", make a clean cut beneath a leaf joint (node), treat with a rooting hormone gel or powder, and place the created semi ripe wood cuttings into either a suitable cutting compost or a shallow container of water and after 4 to 6 weeks in reasonable light and temperatures no lower the 12C you may have some rooted cuttings to replace or enhance your Penstemmon stocks. Good Luck Dioon11