Trimezia

( try - MEZ - ee - uh )

At-A-Glance Information

This genus of flowering perennials needs full sun or light shade and regular water to perform at its peak. They are commonly known as Walking Iris, Apostle's Iris, or Apostle Plant, and produce fans of leaves similar to Iris plants, and flower stems that are about the same height as the rest of the foliage. Flowers have three large outer segments around three inner ones, and are banded in contrasting colors. Flowers last for only a day but are followed in time by new blooms. Take care when planting these flowers in the landscape, as there is some evidence that plant parts of at least some species are toxic to humans and pets if ingested.

trimezia Species and Varietals

the genus Trimezia is a member of the plant family Iridaceae and includes about 80 species. The genus name is derived from the Greek words tri (three) and meze (greater). The genera Neomarica, Pseudotrimezia, and Pseudiris were absorbed by the genus Trimezia. These plants do best in zones 16, 17, 21-24 and H2. To find your zone, click here: Zone Map.

Trimezia caerulea (Neomarica caerulea) (Walking Iris,
This native of Brazil grows to 5.5 feet tall and 2-3 feet wide, with erect leaves. Flower stems support blooms that are blue with centers banded in white, yellow and brown. Flowers pop in summertime along the stems, and can be removed and grown into full plants.

Trimezia candida (Neomarica candida) (White Walking Iris)
These plants are native to Paraguay, Brazil, northeastern Argentina, and Uruguay. The species was first described by Emil Hassler. Flowers are white with purple, red, and yellow markings. Individual plants reach up to 2-3 feet tall when mature and in bloom.

Trimezia fosteriana (Yellow Walking Iris)
These flowering bulbs produce delicate yellow flowers atop green flowering stems, and are widely used in cities in South America as garden ornamentals. The species is native to Venezuela, though plants are grown widely around the globe for their cold tolerance.

Trimezia gracilis (Walking Iris)
This species is native from Mexico to Brazil and reaches 2-2.5 feet tall and 1-1.5 feet wide. Flowers appear in late spring and summertime, and are held close to the foliage. Outer segments are white and inner segments are blue, brown and yellow. Plantlets form on stems which bend to the ground when they are ready to root, hence the common name.

Trimezia humilis (Neomarica humilis)
Native to Venezuela and parts of Brazil. These flowers form strappy green above-ground foliage and produce light yellow flowers with red stripes and bright pink to magenta centers. At maturity, plants typically reach between 18 and 24 inches tall and form clumps over time.

Caring for Trimezia

These interesting flowers are typically purchased as corms or rhizomes and do best in full sun. Ideally, they should be getting between 6 and 8 hours of sun each day for best performance and flowering. Plant them between 1 and 3 feet apart for best coverage and airflow. They appreciate a 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. 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 flowers need consistent moisture to bloom and otherwise perform well.

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 any damaged, diseased, or dead foliage at any time during the growing season, and remove spent flower spikes to neaten up the appearance of plants and encourage reblooms. In cooler climates, it is a good idea to grow these flowers in containers, so that they can be easily brought indoors when temperatures drop in wintertime. Every few years, these flowers will need to be divided, especially if they are being grown in a cramped bed or container. A good indicator of the need for division is when plants begin to struggle to bloom or produce healthy foliage. Dividing will also help increase airflow between plants. For instructions on how to successfully divide Trimezia plants, see the Propagation section below.

Propagation

Trimezia, or Walking Iris, can be propagated by division or 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, especially if you are propagating a hybrid cultivar. To propagate your Walking Iris, follow the instructions below:

Propagating Trimezia 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. 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.
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.
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 2-6 weeks 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 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 Trimezia 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:

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.
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.
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.
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

Trimezia plants, although typically considered resilient, can be susceptible to developing issues with the following pests and diseases in the landscape: