We have found 21 plants that meet your criteria.

Price Pruned
Lavandula angustifolia 'Munstead' Lavender A compact variety with blue-purple flowers NOW £4.99 Buy
Perovskia abrotanoides Russian Sage Silvery white aromatic foliage with long lasting blue flowers £7.99 Buy
Perovskia 'Blue Spire' Russian Sage Violet-blue flowers and silvery foliage. Great planted en masse £7.99 Buy
Price Pruned
Rosa Rhapsody in Blue '('Frantasia') (PBR)' rose (shrub) The closest to a blue rose NOW £10.99 Buy
Syringa vulgaris 'Katherine Havemeyer' Common Lilac Wonderful scented lavender-purple flowers £9.99 Buy
Price Pruned
Buddleja 'Lochinch' Butterfly Bush Fragrant violet-blue flowers all summer NOW £5.99 Buy
Caryopteris x clandonensis 'Heavenly Blue' Bluebeard Piercing, dark blue flowers £6.49 Buy
Ceanothus thyrsiflorus 'Skylark' Californian Lilac A haze of bright blue flowers in early summer £8.99 Buy
Ceanothus 'Autumnal Blue' Californian Lilac Sky-blue flowers in late summer £7.99 Buy
Ceanothus 'Burkwoodii' Californian Lilac Bright blue flowers in summer £8.99 Buy
Ceanothus 'Concha' Californian Lilac Masses of deep blue flowers in spring £6.99 Buy
Ceanothus 'Puget Blue' Californian Lilac Fabulous deep blue flowers £6.99 Buy
Ceratostigma willmottianum 'Desert Skies' Hardy Plumbago A stunning new variety of hardy plumbago £7.49 Buy
Ceratostigma willmottianum 'Forest Blue' Hardy Plumbago Foliage turns wonderful autumnal colours £6.99 Buy
Hibiscus syriacus 'Oiseau Bleu' Hibiscus (syn. Hibiscus syriacus Blue... Late flowering shrub with large blue flowers £9.99 Buy
Hydrangea aspera 'Villosa Group' Rough-leaved Hydrangea Long-lasting, deep mauve flowers in autumn £10.99 Buy
Hydrangea macrophylla 'Mariesii Perfecta' Lacecap Hydrangea (syn. Blue Wave)... Pink or pale blue lacecap flowers £6.99 Buy
Hydrangea serrata 'Bluebird' Hydrangea Distinctive blue flowers and autumn colour £8.99 Buy
Price Pruned
Perovskia atriplicifolia 'Little Spire' Russian Sage A shorter form of the popular Russian sage NOW £7.99 Buy
Price Pruned
Rhododendron 'Blue Diamond Group' Dwarf Rhododendron Vivid violet flowers NOW £10.99 Buy