Recommend a large perennial, idealy blue/purple about 3 feet high.

[ameliagrey]

have a few ideas but need something striking for centre of large border. i am taking away an iron obelisk thingy with a clematis on it because the clem grows too big- re-planting elsewhere-but I need ssomething in its place.

Lots of sun- faces south- and limey dry soil.

how much space have you got?

Delphinium?

Michaelmas daisy?

It helps if you tell us when you want it to flower, too.

Plumbago is nice.

Borage

Agapanthus
Allium
Ceanothus (but would need to be pruned to be kept to that size)
Buddleia (likewise)
Ceratostigma
One of the taller geraniums

What about Rosemary? Beautiful and useful for cooking.

Thanks. None of the above is really suitable I don't want a shrub of any kind - like buddleia- dug zillions of those out from previous owners.

I want something that will flower ideally july-august - already got alliums in there are pale blue iris , agapanthus are lovely but they never flowered- could try again i suppose.

There is something very tall & blue starting with an A- I need to look though the gardening books.

Aconite

beautiful obelisk covered in sweet pea matucana
Salvia Gauranaitica

ceanothus.

How about Russian sage also known as Perovskia ?

Other thoughts are

perennial geranium like Johnsons Blue (although my favourite is Brookside)

Agastache or Blue Hyssop

there's another that's on the tip of my tongue - it's called London blue, but I can't remember the latin name!

baptisia australis

Agastache? Is that what you're thinking of?

What about sweet peas on a frame of the size you want? RHS plant selector also suggests corncockle, tree mallow and echium when I put in roughly what you've described.

Xpost with mrsdistinctly!!

Anchusa Lodden Royalist (Lodden Blue is a lavender I think)

Anchusa that's the one.

It's supposed to be a bitch to grow quite fussy about conditions though..

One of the taller echinops like echinops bannaticus?

Aconite is beautiful but extremely toxic - do you have children or pets?

There are some good salvias available in a range of heights, Salvia pratensis Indigo grows to just under 3ft and flowers from June to September.

Agapanthus take several years to flower and get better every year, if the frost does not kill them. A good nursery make stock an older (hence costlier) specimen that will flower this year.

Penstemon Raven is a favourite of mine but probably not much over 2 ft. Stunning though and long flowering season.

Phlox paniculata Blue Paradise might work

I know you said no shrubs, but Rosa Cardinal de Richelieu might suit, too.

I think you're thinking of aconite too