Veronica prostrata 'Trehane' Royal blue flowers on golden-leaved mounds. £2.60 Out of stock. Spikes of royal blue flowers on bright, yellow-leaved mounds - a stunning contrast and a beautiful plant. Very easy to grow in any good soil. Grows about 15cm (6") high from a central stool and can be cut back to near ground level in autumn. Slowly spreading mounds.