Penstemon Heavenly Blue - Flowering Period

I planted some Penstemon Heavenly Blue last year , which have flowered for the first time this year , mid June . A stunning flower and flower colour After our last torrential deluge a lot of flowers have been knocked of the stems . Now I understood these are a long flowering plant , through to October When a stem has lost its flowers do I need to cut it back or just leave it be ? Will new flower stems emerge.

TIA

 

I don't know about that cultivar Harry but I remember cutting back dead Penstemon stems in early spring before the new flush of growth from the crown so I say leave it be on the plus side now the flowers of gone it will put lots of energy into new growth which will back fabulous cuttings

 

I love Heavenly Blue too.

Definitely cut the dead flower spike off - it's just dead-heading as you would any other plant - this will encourage further spikes to appear throughout the summer (I use the term 'summer' in it's loosest sense of course!). Even at the end of the season when the plant has only perhaps one or two flowers, it's still a good idea to cut these off when they've finished since, in a mild autumn, mine have been known to find the energy to produce a few more flowers.

Penstemons have hollow stems and need protection from frost, (which the old leaves and any 'missed' flower spikes will provide), and although I've read you can cut them back by about a third, once they've truly finished I tend to just leave them alone.

Next Spring, (somewhere around late April or early May), once new shoots appear at the base, then you can cut out all the old/dead stuff at the base. Sometimes, I've found mine don't actually produce new shoots from the base itself, but from existing stems - in which case, cut them back to just above those new shoots.

Although I bought mine as 'hardy perennials', that seems a term open to interpretation, as I've since discovered they're often referred to as 'borderline perennials' and, in any event, are fairly short-lived plants. Like many plants, a lot depends on what sort of winter we have - Pestemons hate sitting in wet, cold soil for long periods, so I'd suggest that next year you take plenty of cuttings (which are really easy to grow).

 

Penstemon heterophylus, of which Heavenly Blue is one of the many cultivars, is a cracking plant!
Fidgetsmum is spot on, although I have always found them to be fully hardy. They are short lived (four or five years ish) as she said, so I always allow a couple of stems to mature and produce seed. Saves storing cuttings that you may not need.
Will happily bloom all summer in flushes.

 

Does that apply to Electric Blue as well? mine are just going over.

 

Absolutely!
Electric Blue has the most vivid flowers of the ones that I've grown and is the most compact.

 

The four Electric Blues that I brought with me when we moved here last November were in pots and survived a couple of -8/9cs which I thought would kill them off but fortunately proved wrong. planted in March they really took off. I hope there will be another flush.

 

Heavenly Blue is gorgeous - a true blue, which is quite rare in the garden. Most 'blue' plants are shades of mauve.

I suspect it has different parentage from some of the garden stalwarts; the leaves are different and I have found it to be more temperamental than other varieties. I have had two 'Heavenly Blues' which were fine for a while, but then decided to keel over for no apparent reason. I'm now on my third and it's still alive and flowering, but not with the same vigour as some of my other penstemons. So I would say, by all means cut back the dead flowering heads, but keep some of the leaves at the base of the stems. As has already been mentioned, the plant will often grow new stems from these, so you are helping to hedge your bets somewhat. And take some cuttings while you can.

 

Can either of these be raised from seed? or is it cuttings-only ?

 

It is a different species Clara - P.heterophyllus.
I can't say that I've found it temperamental, but certainly not long lived.

Seed every time for me Kristen. It's fast growing and saves the hassle of looking after cuttings that you may not need.

 

I'll leave a couple of stems for seed production.

 

Thanks for all the advice on Penstemons Fidgetsmum and Longk . I will complete the dead heading today .
If I save seeds or cuttings at the end of the season would they flower in the first year. I bought my Heavenly Blues as plugs and they did not flower last year.

 

I was googling penstemon heavenly blue and this thread came up. What are the chances eh? When I googled lithodora heavenly blue, the penstemon came up as an alternative. I was thinking I could use them both at the same time. Has anyone's experience of penstemon heavenly blue changed since this thread was started?

G.

 

Most of the penstemons are good, long flowering plants, if you deadhead regularly and Heavenly Blue longer than most.
The lithodora and Heavenly blue would complement each other ....both evergreen and both with varying shades of blue.
My own experience of Heavenly Blue is that it is a reliable plant....not as blue as implied though.
My feeling is they would look good in same area but not immediately adjacent to each other......a plant like artemisia Powys Castle between them would look good I think.

 

Hi Jack , I find that Lithodora ( also known as Lithospermum ) is a Spring flowering ground cover/ rockery mini shrub whereas Penstemons are mostly Summer//Autumn flowering so wouldn't really complement each other.