Have a close look at the image of a rose arbor garden I designed a few years ago and ask yourself what you notice first. Sure, the roses are in prime form and the hanging baskets are glorious, but if you are like me the first thing that catches your eye are the vivid blue flower spikes of the Veronica spicata ‘Royal Candles’ in the lower right-hand corner. I think it garners our attention because we don’t often encounter this hue in the natural world and yet if you look hard enough, there are plants with blue foliage, flowers, or berries for just about any garden. So, let me show you a few options.
Blue Vining Plants for the Vertical Landscape
Vines are a great place to start looking for true blues and Clematis is an obvious choice. A few stalwarts include ‘Multi Blue’, ‘Royalty’, and ‘Will Barron’, although some varieties such as ‘Blue Angel’ are so pale that they often appear white at a distance. The marbled pink, white, and green foliage of Porcelain Vine (Ampelopsis b. ‘Elegans’) may seem like the odd man out, but later in the season, it is adorned with abundant blue and purple berries. Passiflora caerulea is one of the hardiest Passion Flowers (zone 6 when protected) and produces intricate lightly-scented blooms from summer to early autumn.
Blue Flower Bulbs
There are a lot more choices than just tulips and daffodils when you go bulb shopping in the fall, and many blue varieties will also naturalize well. Bulbous iris is a popular choice with most of us choosing the fleeting Iris reticulata; however, a better choice is the later-blooming Dutch Iris (Iris x hollandica) such as ‘Blue Star’, which makes great cut flowers. Glory-of-the-Snow (Chionodoxa forbesii) is an easy plant to naturalize and bears stunning pale blue flowers with a white eye. Our native Camassia quamash or Camas Lily is also occasionally available (from cultured stock) even though it is endangered in many of its natural habitats. And perhaps the bluest of all is the Anemone coronaria (like ‘Harmony Blue’) although many gardeners treat them as annuals. They are actually hardy to zone 7 and will naturalize in well-drained soils.
Blue Shade Plants
(📸 Hosta 'Diamond Lake': Walters Gardens; 📸 Corydalis 'Blue Heron': Terra Nova Nurseries; 📸 Brunnera 'Jack Frost': Walters Gardens)
Shade usually limits your colour palette but blue might be the exception here. Blue Hosta are what first come to mind and there are plenty of superb cultivars such as ‘Blue Angel’, ‘Halcyon’ and ‘Hadspen Blue’, but don’t forget those newer introductions like Shadowland ‘Diamond Lake’, which was hosta of the year in 2022. Blue Himalayan Poppy (Meconopsis betonicifolia) is another must-have in the shade garden but it can be notoriously difficult to grow, so be sure to pinch out any flower buds in its first season. Corydalis ‘Blue Heron’ literally blows the senses with its intense electric-blue flowers and long blooming time, while Brunnera macrophylla ‘Jack Frost’ starts the season with blue forget-me-not flowers and retains its marbled silver foliage until frost.
Blue Shrubs and Conifers
(📸 Picea pungens 'The Blues': Specimen Trees)
Blue flowers are quite rare in shrubs which is why California Lilac (Ceanothus ‘Victoria’) remains a best seller year after year, despite winter losses. Much more durable is the hardy hibiscus (Hibiscus syriacus) which only starts to leaf out when the rhododendrons are in full flower but provides abundant blooms from July to October. Look for the single ‘Blue Bird’ and ‘Blue Satin’ or the semi-double ‘Blue Chiffon’. Conifers are an excellent source of steel-blue foliage with Juniperus squamata ‘Blue Star’ being one of my favourites. For larger feature plants look to Picea pungens ‘The Blues’ or the Weeping Blue Atlas Cedar (Cedrus atlantica ‘Glauca Pendula’) – although the latter is somewhat prone to needle browning during wet springs.
Blue Perennial Borders
The perennial border is the main stage when it comes down to displaying azure blooms, but it is critical to arrange plants according to height. Start with your taller features in the back of the border (or the centre of an island bed) which can include stately Delphiniums (like ‘King Arthur’) or even the architectural Globe Thistle (Echinops ritro) with its spherical blooms that make excellent cut or dried flowers. Coming forward to the mid-border we can always find space for the unusually coloured Phlox paniculata ‘Blue Paradise’ alongside the intensely deep violet-blue flowers of Iris sibirica ‘Ruffled Velvet’, with more to come below.
Blue Rock Gardens
These perennials can be used either on the edge of your mixed perennial border, flowing over the lip of retaining walls, or to provide a cooling blue hue to your dedicated rock or alpine garden. Geranium ‘Johnson’s Blue’ has been a reliable filler plant for decades now, with its floriferous show of large lavender-blue blooms — just shear it back right after flowering to prevent floppiness. My next two choices have a much lower profile and are suitable for edging or trailing over a rock wall: Lithodora ‘Grace Ward’ blooms from late May to August and requires an acidic pH, while the purplish-blue flowers of Campanula ‘Birch Hybrid’ are produced almost all summer when deadheaded.
Blue Fruits and Berries
I couldn’t resist leaving you with a reminder that many common shrubs have attractive blue berries, including female Viburnum davidii and our native Oregon Grapes, such as Mahonia aquifolium, nervosa, and repens. Perhaps the most dramatic blue fruit are the indigo sausage-like beans of the hard-to-find Decaisnea fargesii or Dead Man’s Fingers, which have a slimy edible gel that tastes a lot like lychee nut.