Whether gardeners are trying to compliment their house color, liven up the landscape or it is just a favorite color, a vast array of plants produce blue flowers throughout the year. Blue flowers come in a variety of shapes and sizes and range in almost every color of blue imaginable. Plants types include groundcovers, perennials, annuals, shrubs and trees, so gardeners should have few problems finding a plant to suit their landscape requirements.
Spiderwort (Tradescantia virginiana) is a member of the family Commelinaceae and native to the United States. This perennial grows throughout much of the United States as a wild flower. The blue flowered cultivar is most common but cultivars also bloom in colors of purple, red and white. All have bright yellow stamens. Spiderwort starts its blooming in springtime and continues throughout fall, with flowers remaining open until midday. It is suitable for use in borders, containers, butterfly and native gardens as well as a taller plant in mixed flower gardens. Flowers are a nectar source for butterflies.
Plants grow 1 to 3 feet tall and have a clumping and aggressive spreading habit. It grows in a wide range of light conditions, tolerating full sun to full shade, but full sun produces the best blooming. The plant tolerates dry to moist soils, preferring rich soil mediums. It is a hardy plant with few if any pest problems.
Plumbago (Plumbago auriculata) is a member of the family Plumbagnaceae. It acts as a perennial, evergreen shrub in USDA planting zones 8 through 10, with cooler regions treating it as an annual. Clusters of 1-inch, sky blue flowers bloom spring through late fall. Plumbago forms into a loose mound that requires pruning to control its shape and size. Plants are suitable for use as a large, spreading groundcover, in containers, borders, or where a mass of color is required in flower gardens.
Plants grow anywhere from 3 to 10 feet in height with the same width. Plumbago grown in full sun will produce the best blooms, but plants tolerate partial shade conditions. Tolerant to drought conditions once established, plumbago will look its best when given regular applications of water. Plants prefer slightly acidic, well-draining soil mediums.
Lily of the Nile
Agapanthus (Agapanthus), better known as lily of the Nile, acts as a perennial in USDA planting zones 7 through 11. USDA planting zones 4 through 6 should use agapanthus as an annual or plant inside containers for winter protection. There are quite a few cultivars blooming with blue flowers such as Baby Blue, Blue Triumphator, Donau, Imtermedius and Kobalt. Other cultivars bloom in colors of purples, pink and white. Long spikes fill with clusters of trumpet-like flowers blooming in springtime. The foliage is green and lily-like, making agapanthus a stunning garden addition. It works well along borders, as a specimen, inside containers or in a mixed flower garden.
Plants grow best in areas receiving full sun in the morning and depending on the cultivar grow 12 to 60 inches in height. Agapanthus tolerates a wide variety of well-draining soils. It is relatively tolerant to drought conditions once mature, but will grow best with weekly watering. The plant is relatively hardy and problem-free, tolerating temperatures to 28 degrees Fahrenheit.