Orthrosanthus

( ohr - thro - ZAN - thus )

At-A-Glance Information

Commonly called Morning Flag or Morning Iris, this genus of evergreen perennials grows from rhizomes and needs partial shade in warmer climates and moderate water. They are native to Australia and the Americas. Blooms appear in blue, lavender, or white and open in order from bottom to top in summertime. Flowers look best in the morning, and fade as the day progresses, hence their common names. These flowers are perfect for sunny sloped areas, rock gardens, and containers.

Orthrosanthus Species and Varietals

The genus Orthrosanthus is a member of the plant family Iridaceae and includes nine species. The genus name is derived from the Greek words orthros (meaning morning) and anthos (meaning flower). Morning Flag grows best in zones 14-17 and 19-24. To find your zone, click here: Zone Map.

Orthrosanthus chimboracensis (Morning Iris)
This species produces clumps of foliage 1-1.5 feet tall and pale blue to medium-blue flowers held on 2-foot tall stems. These plants are native to Chiapas, Costa Rica, Panama, Colombia, Venezuela, Ecuador, Peru, Bolivia, and northwestern areas of Brazil.
 
Orthrosanthus multiflorus (Australian Flag Iris)
This species creates a 1-2 foot tall, 1 foot wide clump of foliage from which a thin, green stem rises, carrying pale to bright blue flowers. This species is heat-tolerant and is great at providing foliage to landscapes. This species is native to Australia and Victoria.

Caring for Orthrosanthus

Choose a space in the landscape that receives full sun to partial shade during the day. Ideally, these plants should be getting between 6 and 8 hours of direct sun each day for best flowering and performance, but do appreciate a good amount of shade in the late afternoon when temperatures are at their peak. They prefer to be planted in well-draining, moderately fertile soil with a pH of between 6.0 and 7.0 (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. Water newly planted Orthrosanthus flowers regularly to help them develop strong root systems. At maturity, these plants are drought-tolerant, able to get by on rainwater alone with some supplemental waterings in the warmest months of the year. Mulch around the base of plants to increase soil moisture retention, suppress weed growth, and maintain consistent soil temperatures.

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. These plants are not heavy feeders, and this should be sufficient to provide the necessary nutrients for the active growing and flowering seasons. Pruning is simple; remove flowering stems as they fade if desired. At the end of the flowering season is the best time to prune the entire plant. At this time, remove all spent flowering stems and clean up any dead, damaged, or diseased foliage.

Propagation

Orthrosanthus can be propagated either by division or from seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the division 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 Morning Flag, follow the instructions below:

Propagating Orthrosanthus by Seed
  1. 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. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand. You will also, after a few weeks, need individual 3-inch pots for each seedling that grows.
  2. Harvest your seeds. The seed heads on plants are pretty easy to spot, they're 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 continue 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.
  3. In either late winter or early springtime, get your container prepared. 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 14-28 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.
  4. 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 65 and 72 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.

Propagating Orthrosanthus by Division
This type of propagation is relatively simple; you will need a clean shovel, mulch, fresh soil (any kind will do, though it does need to be well-draining), compost and pots (only necessary if you will be saving divided plants for transporting elsewhere). Division is best done in very early spring (after the plant has entered dormancy, but before it has begun its new spring growth), and needs to be done every few years regardless of whether you have the goal of propagating the plants for best performance. To propagate by division, follow these steps:
  1. Using a shovel, dig up your existing plant. Start from the outside and work your way in to avoid damaging the root(s). Once you have worked it up out of the ground, lay it out.
  2. Start to tease apart the roots with your gloved fingers. Once the roots are untangled, separate your plant into segments, ensuring that each one has at least one thick root section attached.
  3. Prepare your pot(s) or new planting site(s) with amended, well-draining soil. You can either bring in new soil or simply amend your existing soil with compost to complete this task. Then, plant your divisions and water thoroughly.
  4. Apply a thick layer of mulch over the new planting to protect it from cold weather as it acclimates to its new home. Then, enjoy watching it sprout in the next growing season.

Problems and Pests

Orthrosanthus plants are susceptible to developing issues with the following pests and diseases in the landscape:
  • Aphids
  • Slugs and Snails
For more information on these pests and diseases, including how to treat and manage them, consult the following pages:
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Gallery

Australian Flag Iris provides grassy foliage and fairy-wand type inflorescences.
These plants look best when planted en masse.
Individual flowers on the stem open from the base upwards and last just one day.
Bees are important pollinators of Orthrosanthus flowers.
Flowers are seen mostly in blues and purples, but can also be white.
This narrow strip of soil is perfect for growing Morning Iris.

Videos

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Resources

Propagating Morning Iris (Orthrosanthus polystachyus) (PDF)
Orthrosanthus multiflorus (Australian Morning Star)
Wikipedia: Orthrosanthus
The New Sunset Western Garden Book: The Ultimate Gardening Guide (2012) - Page 465, Orthrosanthus