What should I plant here?

zugenie

South facing, neutral to slightly acidic sandy loam, although thickly mulched so holding the moisture well at the moment! Cottage garden style herbaceous perennials, white, purples, pinks and blues is the colour palette.

There’s a gap behind the tree and front of the hydrangeas that I’d like to fill with something, the tree is an amelanchier, hydrangeas are annabelle strong. 

I’m not too fussed height wise, I’d be happy with ground cover or something taller. I did ponder a shrubby salvia as I have one called cherry lips, and I figure it will tolerate the soil being drier because of the surrounding plants. Also thought maybe geraniums or mexican fleabane? Would be grateful for your ideas, please!

TheGreenMan

How about some Nepeta?  Bees and other flying types love it; you can get some low ones; higher ones; bushy ones; they need very little looking after and come back each year (in my experience) with no effort from me.

TheGreenMan

Or a euphorbia.  Black pearl, Ascot Rainbow etc would look lovely bobbing about behind the trunk of your tree.

GardenerSuze

@zugenie I think I would look at the plants you already have I know it is nice to have a treat and plant something new but you could repeat some of the plants you already have.
You do have alot of green round/oval leaves in your scheme, perhaps a grass or a spiky leaf for contrast or maybe a coloured leaf?

zugenie

@TheGreenMan does nepeta attract cats? I know catnip is in the same family so I’m always paranoid about it!! I’ll have a look at some euphorbias, thank you!

@GardenerSuze I’m not a massive plant repeater, other than different cultivars, thank you!

TheGreenMan

zugenie said:

@TheGreenMan does nepeta attract cats? I know catnip is in the same family so I’m always paranoid about it!! I’ll have a look at some euphorbias, thank you!

It does but I only had one instance of it being squashed last summer.  It bounced back after a few days.  We don't have a lot of cats around here though. 

You could go big and get a Euphrobia Honey Pot.  I'm in love with mine.  Gonna get another one when the GCget them back in. Actually it will probs be too big for that space.

GardenerSuze

@zugenie I also think E Honey Pot might be too big for the space.  Like you I have recently planted a multi stemmed Amelanchier, I planted some things nearby but I am trying to be careful of the roots.

Plantminded

How about a Geum @zugenie ?  With the flowers waving around on long stems they'd make a nice contrast to the other perennials there.   There's been quite a few featured on the Garden Gallery thread recently.

TheGreenMan

I was just coming on to suggest a Geum. I have a Mrs Bradshaw in my south facing border and she flowered non stop through to late Autumn. I loved her so much I bought three more recently. 

Fairygirl

Looking at your colour preferences @zugenie, one of the Veronicas might suit, or the shorter Verbena - hastata. There isn't a huge amount of room, allowing for everything to mature, but those should be ok. Geums are yellows/oranges/reds, so they would be a bit bright. 
The main problem that I can see is - when the Amelanchier is in full flow, that bit will be shadier, so something that will cope with semi shade is probably the most suitable. I have white and purple Liatris in a site that doesn't get full sun, so that might suit.  

Plantminded

As your tree's canopy is already quite high, I don't think shading's going to be a problem in that spot.  If Geum appeals, I've just bought some Geum Scarlet Tempest - they are lovely with a much longer flowering period than others.  It depends on whether you like them!  Staying with your colour palette, there's a Verbena with dark foliage and small purple flowers which is interesting, Verbena Bampton.