This delicate little Primula ‘Elizabeth Burrow’ is not the best example of a purple patch plant as it is little bigger than a £2 coin. Primula Denticula however can be a real stunner with lilac or purple flowers on lollipop stems. This is just an example of the range of purple colourings available on modern plants ranging from deep violet to lilac.
Also from the Primula family come the Japonica and Harlow Carr Hybrids that often sport a purple hue to the flower-heads.
At the red end of the purple spectrum this cyclamen make a strong colour statement and it could be paired with the 18″ high Allium hollandicum ‘Purple Sensation’. There are also many purple Rhododendrons for early flowering like the compact Ramapo.
Sometimes with colour ‘less can be more’ and I would high light your purple theme with a simple and occasional white flower for contrast.
To add variety I would include purple leaves into a patch particularly Purple Sage, Bronze Fennel and some Dahlias from the Bishop Family. Some Coleus, Heuchera Plum Royale and purple leaved Oxalis could go at the front of a border in your garden.
Iris germanica are a firm blue-purple favourite. Another sage is the perennial Salvia ‘May Night’ with bright green leaves but violet-blue flowers. The range of plants is significan but try get varieties that flower when you want to show the colour harmony
These Orchids are not unlike the colour scheme for Toad Lilies (tricyrtis formosana) that can grow upto 3 feet tall. Also flowering in Autumn is Lobelia Vedrariensis with spikes of small purple flowers and of course the Michaelmas daisy Mönch variety will enhance your purple patch.
Give purple a chance and see what you can achieve with this of colour . For Purple Pansys