So many people come in asking for flowers that are true blue. Here are some photos of perennial blue flowers, some border on being close to purple/lavender. Common names are in parentheses: Aconitum napellus (Monkshood) zones 3-7, Delphinium Pacific Giants 'Summer Skies' and 'Blue Bird' (Larkspur) zones 3-8, Penstemon heterophyllus 'Electric Blue' (Beardtongue) zones 6-9, Scabiosa causcasica 'Fama' (Pincushion flower) zones 4-10, Tradescantia anersoniana 'Sweet Kate' (Spiderwort) zones 4-9, Agapanthus africanus 'Blue' (Lily of the Nile) zones 7-9, Meconopsis betonicifolia (Himalayan Blue Poppy) zones 7-9, Salvia guaranitica 'Black and Blue' zones 8-9, Lobelia siphillitica zones 5-9, Brunnera macrophylla 'Jack Frost' zones 3-8, Ecinops ritro (Blue Globe Thistle) zones 3-9, Geranium 'Johnson's Blue' zones 4-9. Others not pictured are Centaurea montana (perennial bachelor buttons or cornflower) zones 3-9, Linum perenne (Blue Flax) zones 4-8, Lupinus Russell Hybrids Blue (Blue Lupines) zones 4-9. So far this is quite a list for perennials, I'm working on a list of blue flowered ground covers, annuals, and shrubs too and will post soon. Think I'll do a list of white flowers eventually because so many people like to have white gardens too.
