Hot Border Blues - Suggestions Please!

Nollie

I have a lot of hot balls, as in globular or daisy shaped flowers - dahlias, roses, heleniums, echinaceas etc., in shades of orange, yellow and red.

The purple spires that are meant to intersperse the hot-toned balls and add a cooler rhythm to the border turn out lilac or soft pink/mauve here (inc. agastache black adder and blue boa, salvia amistad and mainacht). Salvia Black and Bloom is good, but too big and bulky (more foliage than flower) to do the interspersing thing. Salvia caradonna holds its purple colour well, but goes over so very early.

So I reckon I need to go bionic blue to get purple or at least something that does not fade into the background. Ideally that flowers mid-late summer to take over from the caradonna/help hide its boring foliage.

So does such a thing exist? A deep but vivid blue or violet spire or bold plant that flowers late summer? Maybe 50-70cm. 

I am stumping myself so need some help and suggestions please!

B3

Heliotrope looked good with reds in the formal garden outside a glasshouse at Kew last week. I didn't take a picture but maybe one of the others did.

JennyJ

Can you grow Veronica spicata where you are? There are blue varieties and some more purple ones. Or maybe Teucrium "purple tails"? Verbascum phoenicium "violetta" is a good purple here too.

Omori

Not a spire but is bionic blue and flowering right now: cornflowers.  

Buttercupdays

How about Perovskia - loves hot, sunny sites and long flowering, but maybe not blue enough?

fidgetbones

Salvia Amistad grows five ft high. Easily propagated from cuttings to give a block of five or seven plants to make a big impact at back of border.

JennyJ

Salvia "Blue note" is quite a good blue here but the flowers are small and the plant is quite short, so it doesn't have the impact of "Black and bloom".

I would suggest lupins but they'd probably go over far too early for you.

Some of the eryngiums are blue although not spires (but some are more silver or lilac-ish so you'd probably want to buy locally if possible so you could see what you were getting).

AnniD

Commelina is real "in your face" shade of blue, but may be a little short (around 30cm).
Agapanthus? 

JennyJ

Carrying on thinking "aloud", monkswood is a decent blue and flowering now in my garden at about 4 feet (dry conditions here tend to make things a bit shorter than advertised), but maybe it's still too tall for you.  Baptisia is blue but too early and doesn't last long in flower. A good late-summer blue is Ceratostigma willmottianum, but it's a rounded small shrub so the wrong shape. Perennial cornflowers are blue but for me the flowers are a bit sparse and the plants are straggly and ugly (thinking of getting rid of them.).

ForTheBees

Omori said:

Not a spire but is bionic blue and flowering right now: cornflowers.  

Likewise electric blue chicory. 

Nollie

Brilliant, thanks for all your suggestions, lots I need to look up!

Although it is lilac, the Agastache Black Adder is incredibly floriferous and tall (too tall) but does a good job at the back of the border. I also have Amistad at the back (a tad pinky here) but its basically over now and is only flowering sporadically.

Yes ideally, bionic blue/violet. I’m not averse to some shorter ones at the front. I do like the look of Verbascum Violetta. Cornflowers - a bit globular, perhaps, but certainly bionic. A blue Agapanthus is a thought... I was also thinking Aconitum Napellus and Anchusa Lodden Royalist but maybe a bit tame.  Glads! purple glads... hmm, not that keen on glads, but...