Probably the god awful weather we're having. Ive still got herbaceous perennials emerging !!!

All bets are off this year - some things flowered early, others have never really got going - the weather's been completely bonkers...

It's still quite early for some penstemmons to be in flower and as others have said the weather has slowed lots of things.

Give it time . they'll probably be in flower in about a month

Thanks :)

None of mine have flowers yet either.

Some of mine have buds, others no sign of buds at all yet

I agree with Anchorman, they do flower later here. I usually have them in full bloom from mid august to late sept.

Some of my Penstemons are in flower in the sunny border. Others that are part in the shade are way behind. I like that, because the later ones fill in with some later colour, just as the garden is getting rather colourless.