Indigofera

( in - dih - GOFF - er -uh )

At-A-Glance Information

Indigofera, commonly called Indigo Bush, is a genus of flowering deciduous shrubs and small trees that require regular water. They have woody growth and ferny foliage, and are versatile additions to gardens. Flowers are small and clustered, appearing in spring, summer and fall. These plants are sensitive to frost, and are native to tropical areas throughout the globe. Indigo Bush has been used historically for thousands of years to produce blue dye used for coloring clothing and other textiles. In the landscape, they are commonly used as specimen trees and shrubs or as groundcover. Take care when planting these trees and shrubs in the landscape, as some species contain toxic compounds, and should not be consumed by humans or pets.

Indigofera Species and Varietals

This genus Indigofera includes 750 species and is a member of the Legume plant family Fabaceae. They are related to plants in the genus Baptisia. The genus name is derived from the Latin words for 'blue dye' (indigo) and 'to bear' (fera). Indigo Bush grows best in zones 2b-9 and 14-21. For more growing information, see the descriptions below. To find your zone, click here: Zone Map.

Indigofera amblyantha (Chinese Indigo, Pink-Flowered Indigo, Chinese Bush Indigo)
This species is native to central and southern China, and is a shrub that produces upright stems covered with green leaves and topped with pink flowers. Individual shrubs reach up to 6 feet tall and bloom from May through September. This species is a popular choice for mixed beds, hedges, borders, massing, and containers, and grows well in USDA hardiness zones 6-9.

Indigofera australis (Austral Indigo, Australian Indigo)
This shrub native to Australia grows best in USDA hardiness zones 9-11 or Sunset growing zones 14-24, and reaches 5 feet tall and wide at maturity. Magenta flowers bloom in clusters from July through November. Leaves are green to blue-green. This species needs partial shade and can tolerate salty soils.

Indigofera decora (Indigofera incarnata) (Summer Wisteria, Chinese Indigo)
This species is native to China and Japan, and gets 1 to 2.5 feet tall and 3 feet wide. Has arching branches and narrow, drooping flower clusters of white and pink. Needs full sun. These wide, spreading shrubs are somewhat drought and heat tolerant, but do prefer late afternoon shade. They do well in USDA hardiness zones 5-10 and are considered invasive in the southeastern United States, Australia, and Sri Lanka.

Indigofera hilaris (Red Bush Indigo, Gay Indigofera, Red Indigo Bush)
These tropical plants are perennial shrublets that form erect stems and green foliage. Flowers are reddish-pink to carmine-colored, and bloom from July to December in the plant's native range (tropical Africa). This species grows well in USDA hardiness zones 10-12 and reaches 2 feet tall.

Indigofera kirilowii (Kirilow's Indigo, Chinese Indigo)
This species is native to northern China, Korea and Japan, and can reach 2.5-3 feet tall and 3 feet wide. Shoots of flowers are erect and rose-pink. Requires full sun. This species grows well in USDA hardiness zones 4-8; it will die back to the ground in zones 4 and 5 each year and re-sprout in spring.

Indigofera pendula (Weeping Indigo, Weeping Indigofera, Weeping Shrub)
This species is native to south-central China and grows well in USDA hardiness zones 6-10. Plants reach up to 10 feet tall and 3 feet wide. Flowers are pink and hang from branches in loose panicles. Main cultivar 'Shangri-la' (pictured) is a choice ornamental for landscapes, and features two-tone rose-purple blossoms.

Indigofera suffruticosa (Guatemalan Indigo, Small-Leaved Indigo, West Indian Indigo, Wild Indigo, Anil)
These plants are native to subtropical and tropical areas in the Americas, and has been introduced to many other areas around the globe. It forms an erect, branching shrub to 3.3 feet tall and is typically found in disturbed soils. This species is considered invasive in Hawai'i, Tonga, Guam, New Caledonia, Africa, Asia, the Caribbean and Australia.

Caring for Indigofera

Take care when planting these trees and shrubs in the landscape as some species contain toxic compounds and should not be consumed by humans or pets. Plant Indigofera in a space in the landscape that receives full sun to partial shade; ideally, they appreciate between 6 and 8 hours of sun each day for the best blooms, but appreciate some afternoon shade. Ensure that soil is well-draining, rich in nutrients, and has a pH of between 6.0 and 7.5 (slightly acidic to neutral). If local soils are particularly poor in nutrients or do not drain well, make sure to amend the planting area with plenty of organic compost before installing. Apply a layer of mulch around the planting area to suppress weed growth, maintain consistent soil temperatures, and to increase soil moisture retention. Water new plantings regularly as they establish a strong root system in their new home. At maturity, these plants perform well in consistently moist soils. As a general rule of thumb, water whenever the top two inches of soil feels dry to the touch.

Fertilize yearly in early springtime with an application of 2 inches of compost around the base of plants. Pull mulch back before applying, work the compost gently into the soil a bit, water it in, and then replace mulch. Frost can kill these shrubs to the ground, but they will regrow and bloom on new wood the following season. These shrubs need hard pruning during their dormant season (usually early springtime) to keep a compact, attractive shape. These plants can survive in the landscape for between 5 and 15 years on average before needing to be replaced.

Propagation

Indigofera can be propagated either by using cuttings or from seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the cutting method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant. To propagate your shrub, follow the instructions below:

Propagating Indigofera by Cutting

Gather your materials. You'll need a clean, sanitized, sharp pair of garden shears, rooting hormone, a pencil, and a 3-inch pot filled with well-draining compost or other organic material. A good substrate for propagation of cuttings is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
In summertime, choose the plant that you'd like to propagate. Ensure that this plant has had a good watering the night before, as this will improve the chances your cutting will take root. Cut one or more 3-6 inch portion(s) of the end of a non-blooming branch and strip the leaves off of the lower half. Make a hole in your planting medium by pushing your pencil into the soil. Dip the end of the stem in rooting hormone, and plant it in your pot. Fill in soil around the cutting to support it, but do not pack it down too much.
Moisten with water, and ensure that the pot has good drainage. Your pot should be kept in warm, sunny conditions indoors (and not in direct sunlight). Water whenever your soil is dry under the top layer. After about four to six weeks have passed, your cutting should be rooted. When you notice new growth, you'll know you have roots.
Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring, when you can transplant it to its new home. Ensure that the last frost of the year has occurred before doing this, as it can seriously damage your new shrub.

Propagating Indigofera by Seed

Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. The best potting medium for seed germination is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
Harvest your seeds. The seed pods on these plants are pretty easy to spot, they're large and dangle from the branches, left behind after flowers have faded. Once they have dried out and begun to split open, you can harvest the seeds inside. Cut them off of the plant, placing them in a paper bag. Harvest as many as you can, and place the paper bag in a dry, cool, dark area. They will begin to split open and release the seeds contained inside. Once they have been released, take them out of the bag and put them in a container so you can work with them.
Indigofera seeds have a hard coating that protects them, but this coating also makes it a little difficult to get them to germinate. We can help the process along by scarifying them with sandpaper (or simply rubbing them against an abrasive surface). Do this with as many seeds as you can; they will probably not all sow, and the ones that do will be of varying characteristics. The more seeds you plant, the more chances you will have to get the resulting shrub you want. Place your seeds in lukewarm water for six hours. Viable seeds will sink to the bottom, and non-viable seeds will float to the top. You can discard any seeds that float.
Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes 15-30 days from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 70 and 80 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.

Seeds are contained inside pods that will turn brown and dry when mature.

Indigofera seeds are small and hard.

Problems and Pests

Indigofera doesn't commonly suffer from any serious pest or diseases, but it can be susceptible to the following if the right growing conditions aren't met: