Blue flowers and plants give a cool feel to a landscape. Plant masses of blue flowing plants for impact and to create a refreshing oasis. Use different varieties, but group plants with similar sun and water needs for the best results. Mix in plants with contrasting flower colors or go for a monochromatic look for impact. Varying heights and textures add interest to the landscape, whether your yard is large or small.
Plumbago is an evergreen shrub with a vining form. It has an irregular shape and heavily foliated with simple, 2-inch-long, light green leaves. Plumbago flowers are a pretty azure blue, with a slender, funnel-form shape. Plumbago blooms much of the year and is very showy. Plumbago is a warm weather plant, but is grown as an annual above USDA hardiness zone 9. Grow plumbago in full sun for the best flowering, on various, nutrient-rich soils.
Morning glory (Ipomea nil) is a climbing species with vigorous growth and blue, bell-shaped flowers. The individual flowers are short-lived, but many blooms open in succession during summer and early autumn. Morning glory is hardy in zones 9 through 12. Grow morning glories in full sun on various soils.
Delphiniums are usually seen with tall, upright, spike-like stems of blue flowers, though some species of delphinium have short-branched spikes of flowers. Delphiniums come in white, red, or pale green flowers, but are characteristically blue or violet. Grow delphiniums in full sun, in moist, nutrient-rich, well-drained soil. Cut back withered delphinium foliage to maintain its vigorous growth.
Hydrangeas (Hydrangea macrophylla) are rounded, symmetrical, deciduous shrubs, commonly seen 3 to 5 feet tall, with equal spread. Hydrangeas are hardy in zones 5 through 10 and have simple, 9-inch-long, thick leaves. Its flowers are large, flat topped clusters called cymes and are blue when planted in acidic soils. Alkaline soils yield pink hydrangea flowers, and neutral soils yield white. Grow hydrangeas in partial to fairly deep shade, in nutrient-rich, acidic soil (for blue flowers).
Forget-me-nots (Myosotis alpestris) are small plants, growing 4 to 6 inches tall, with equal width, and have simple, blunt, lance-shaped leaves and dainty blue flowers with yellow centers. This species blooms in spring through early summer and is hardy in zones 4 through 10. Grow forget-me-nots in sun or shade on moist soils. They are well-suited to woodland gardens or near water.