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Plant of the Month: Blue Flowering Plants

November 16, 2017 - 10:47am

When choosing plants for a garden, you may base your decision on a variety of factors. We sometimes decide to choose plants based on a color palette we like. This is easy to do if you want a garden of greenery. The choices abound. Many lovely tropical plants do not produce colorful flowers but have beautiful leaves in all shapes, sizes and shades of green. If you want brighter colors, you may choose among the numerous species that flower in red, orange and yellow. For dark contrast, you may select some of the purple flowering varieties.

To add interest to a garden, you may want to include true blue flowers. This color is rather rare in the flowering world and for this reason blue flowers can be an eye catching addition when mixed with other colors and can make a truly remarkable impression when featured solo or mixed with other blue species.

Blue, of course, is the color of the sky and of water. You can bring these elements into your garden by including plants with blue flowers. A bank of blue flowers can bring the airy openess of the sky or the coolness of water into your garden without either element being present.

Starting with ground covers or understory plants in blue you might consider blue daze (Evolvulus glomeratus “Grandiflorus”), which is a low growing plant from Brazil that can grow to 18 inches. It grows well in full sun and produces small, bright blue blossoms most of the year. It makes a great border plant and has moderate drought tolerance.

If you want a blue understory plant that can get between 18-36 six inches, consider one of the blue varieties of agapanthus. Several dwarf varieties in light blue are available. The deepest blue of this genus, Agapanthus africanus “Elaine,” is a taller variety and usually locally available. All are native to South Africa and are sometimes known as African lilies. They can grow in full sun or partial shade and are both heat and drought tolerant.

A small shrub, blue plumbago (Plumbago auriculate) can mound to 6 feet and is often grown as a hedge or to cover a fence or a bank. The flowers appear nearly year-round in light blue clusters. It is another South African native that grows well in full sun and has good heat and drought tolerance. A close relative of this plant is the Hawaiian heritage plant iliee (Plumbago zeylanica) which produces white flowers but has a similar growth habit.

Blue ginger (Dichorisandra thyrsiflora), though not a true ginger, is considered a medium shrub. It bears flowers on tall stems that can reach 8 feet in height and hold clusters of beautiful dark blue blossoms. An upland Brazilian native, it prefers a shaded spot with rich, moist soil. It can be mass planted as a hedge, but is quite striking as a specimen plant grown singly or in small numbers out of full sun.

Though hydrangeas will grow at elevations above 800 feet in Hawaii, they do best at higher locations that have cool air and moist soil that mimics their native habits in the eastern Himalayas, southern China and Japan. They are considered medium-sized shrubs and can get as tall as 8 feet where conditions are ideal. The hydrangea (Hydrangea macrophylia) that grows best here produces flowers whose color depends on the pH of the soil. To produce blue flowers they need to be grown in acid soil between pH 5.5-4.5. Adding aluminum sulfate to the soil also encourages blue flowers. In less acidic soils, the blooms may be white or pink.

Golden dewdrop (Duranta erecta) is a larger blue-flowering shrub that can grow to 12 feet and equally wide in an ideal location. The name relates to the small golden orbs that follow flowering. The flowers, however, are a lovely dark blue. The plant is native to tropical areas of the Americas and is often grouped as a hedge or privacy screen but also makes a wonderful solo specimen plant. It does well in full sun, is moderately drought and salt tolerant with good wind tolerance.

Perhaps the most striking blue flowering plant for a Hawaiian garden is the blue jade vine (Strongylodon macrobotrys). Its spectacular turquoise color attracts lots of attention when the long pendant racemes appear in the spring bearing an abundance of claw-shaped flowers. The plant is native to the Philippines and grows well here when planted in rich, moist soil with good drainage. It requires strong support to grow and produce flowers, making it a perfect plant to climb a large tree or cover a pergola or sturdy trellis.

All of these lovely specimens can be grown here without much disease or insect pressure if planted in the right place. Maybe it’s time to consider adding something blue to your garden. Take a look around in local nurseries and garden departments as most of these are often available locally.

Diana Duff is a plant adviser, educator and consultant living in a dryland forest.

Gardening Events

Friday through next Sunday: “Kona Coffee Festival,” a 10-day event celebrating the Kona coffee harvest. Kona coffee and food events offer tastings, and hands-on cultural events help tell the story of Kona’s rich coffee history. Info: Visit

Saturday: “Work Day at Amy Greenwell Garden,” 9 a.m.-12:30 p.m. Meet at the Garden Visitor Center across from the Manago Hotel in Captain Cook. Volunteers will be able to help with garden maintenance and are invited to bring a brownbag lunch. Water and snacks provided. Info: Call Peter at 323-3318.

Farmer Direct Markets

Wednesday: “Sunset Farmers Market,” 2-6 p.m. in the HPM parking lot, 74-5511 Luhia St., in Kailua-Kona

Wednesday: “Hooulu Farmers Market,” 9 a.m.-2 p.m. at Sheraton Kona Resort &Spa at Keauhou Bay

Friday: “Pure Kona Market,” 9 a.m.-5 p.m. at Amy Greenwell Garden in Captain Cook

Saturday: “Keauhou Farmers Market,” 8 a.m.-noon at Keauhou Shopping Center

“Kamuela Farmer’s Market,” 7 a.m.-noon at Pukalani Stables

Sunday: “Pure Kona Green Market,” 9 a.m.-2 p.m. at Amy Greenwell Garden in Captain Cook

Tuesday-Saturday: “U-Pick greens and produce,” 10 a.m.-4 p.m. at Tropical Edibles Nursery in Captain Cook

Plant Advice Lines


Tuesdays, Thursdays: 9 a.m.-noon at UH-CES in Kainaliu at 322-4892

Mondays, Tuesdays, Fridays: 9 a.m.-noon at UH-CES in Hilo at 981-5199 or

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