Purple foliage plants for shade?

I am stumbling my way through trying to redesign my garden, and I was hoping to ask for some advice from some of the knowledgeable people on the forum. I am currently replanting a small, shady flowerbed in my small, shady London garden; it's against a brick wall, with a small apple tree in the middle of it. The soil is a bit clayey but actually not bad; and the bed gets some sun at the front but it's mostly in shade at the back so all the plants need to be shade tolerant. I have gone for a colour-scheme of yellowy-green, with some notes of purple.

My question is about the back of the flowerbed - I have two clusters of three euphorbia amygladoides robbiae at the back, acting as a greeny-yellow backdrop to some slightly shorter plants in purples and yellows eg geranium clerkei 'Kashmir Purple', and a cluster of corydalis lutea. The clusters of euphorbias are at the two back corners, but there is a gap about 80 cm across left between them, directly behind the apple tree. I wanted to fill in the gap with something that would  provide some structure behind the tree without being too eyecatching (as it will be partially hidden), and possibly provide some contrast in keeping with the colour theme.

I was wondering whether it would be a horrible mistake to put in euphorbia amygladoides purpurea - the same shaped plant but in a contrasting purple/bronze? But I have a feeling that that may be overpowering, and make it look as if the bed is striped like a mint humbug? Any ideas as to what would work in the space? I am a complete novice at this and most of what I have learned in the last three years has come from getting it wrong the first time round, so I would really appreciate any advice to help me shortcut any design disasters!

Thank you!

Hi Viola111,

I'm certainly no expert, and I love Euphorbia (I currently have 8), but as you already have 2 lovely ones in that particualr space, I'd go for something different.  I'd put in a Vinca Major (Periwinkle).  Lovely yellow and green varigated leaves, with lilacy blue flowers.  It flowers for ages, is evergreen and puts out runners very easily, giving new plants when you pin them down so they can root.  I have them in full sun, partial shade and shade and they always come up trumps for me.  There is also a Vinca Minor, which is plain green evergreen leaves, but has small white flowers.  Both cheap plants to buy too, especially as they so freely give you freebies.

Good luck, Yvie

Heucheras  do well in semi-shade, and you can get some very deep purple ones. The darkest one that I have is Obsidian, which is practically black. A good mid purple is Emperors Cloak. 

Actea simplex 'Brunette' is a terrific plant for shade, deep purple finely cut leaves, 5 foot tall when its white spikes are in flower. I got one two years ago, at Holcombe Hall in Norfolk, and it is terrific, but it likes moist soil and doesn't like much sun. It would go really well in the middle / back of a border. Here's some info on it:

http://www.primrosebank.co.uk/perennialdesc.asp?perennialid=6

That's three brilliant ideas - thank you! I will go and stare at my flowerbed and try to imagine it with a vinca, a heuchera and an actea, and see which works!

I don't know Actea simplex - it sounds gorgeous and having just googled it it's a lovely plant, I'm just wondering whether it would be too tall under the tree.

Lots of food for thought - thank you!

Just to say a followup thank you to Gold1locks - I decided to go for a heuchera, and after looking at lots of them actually decided to go for something in the yellowy green spectrum (a Citronelle) and rely on bulbs to introduce the purple touches. It is now planted and looks great. Thank you for the idea!

And a good thing about heucheras is that they are evergreen (or ever purple!). Funny thing - OH was admiring a H Citronelle in our local garden centre just yesterday. 

Be aware  that they need dividing every three years or so, as they cradulaly rise above soil level on thick woody stems. Take pieces from the edge, chuck the middle bit, and you shoudl get four or five young healthy ones.

And watch out for vine weevil larvae, which love heucheras.  I water my best ones twice a year with Provado Vine Weevil Killer as a protective measure. If you see one looking poorly, treat these pests as No 1 suspect. Lift and inspect the roots. If you spot it soon enough and treat the roots with provado and repot, you can save them and they will soon recover.