Blue Foliage Plants: Top Picks for a Cool Garden Palette

Following our recent exploration of silver-toned foliage, we turn now to the captivating world of blue-leaved plants. Blue foliage creates a serene, cooling effect in the garden, especially striking against summer skies. Here are five exceptional cultivars that bring this elusive hue to your landscape.

1. Cerinthe major 'Purpurascens' (Honeywort)

This upright annual reaches 60 cm tall, with foliage that shifts between blue and turquoise from spring through summer. Its purple flowers feature a vivid yellow center, complemented by purple bracts at the base. A magnet for bees, honeywort thrives with regular cutting. It prefers well-drained soil in a sheltered, sunny spot but tolerates a wide range of soil types and pH levels.

2. Festuca glauca 'Elijah Blue'

A compact, clump-forming evergreen grass, 'Elijah Blue' produces striking blue tufts of wiry foliage about 20 cm tall. In summer, tiny blue-green flowers appear, fading to pale brown by autumn—though they're barely noticeable and don't detract from the foliage. This low-maintenance grass handles exposure and extreme pH levels with ease.

3. Helictotrichon sempervirens (Blue Oat Grass)

If you love Festuca but need more height, blue oat grass is an excellent choice. This dense, tufted evergreen grows to 1.4 meters, with rigid, spiky leaves in blue or silver tones year-round. Summer brings brown flower spikelets on broad panicles when grown in full sun. It thrives in most conditions, even poor soil, preferring alkaline ground. Propagate by division after mid-summer flowering.

4. Hosta 'Hadspen Blue'

This small herbaceous perennial reaches 35 cm in 2–5 years. Its smooth, blue-grey, heart-shaped leaves form a neat clump, topped by bell-shaped mauve flowers in summer. 'Hadspen Blue' performs best in heavy clay or loam, in a sheltered spot with acidic pH; sandy soil may cause leaf yellowing. A bonus: slugs and snails tend to avoid blue-leaved hostas.

5. Additional Blue Foliage Gems

Beyond these five, consider Senecio serpens (blue chalk sticks) for succulent blue-gray foliage, Eucalyptus gunnii 'Azura' for aromatic blue-green leaves, or Picea pungens 'Glauca' (Colorado blue spruce) for a majestic blue-needled conifer. Each adds a unique texture and tone to the blue palette.