The Stromanthe sanguinea “Triostar” (aka Stromanthe thalia due to a recent name change) is a stunning member of the Maranta or prayer plant family (Marantaceae).[1]
It is often marketed as Stromanthe “Tricolor” for the three eye-catching colors often found on their variegated oblong leaves: white, cream, and green mixed with bright reddish-pink undersides.
They are also sometimes known as Tricolor prayer plants for their daily light-chasing up and down motions, which resemble hands clasped in prayer.
Stromanthe Triostar Care
Native to the Brazilian tropical rainforests, these plants prefer high humidities and warm temperatures such as those found in USDA zones 9-11 or in greenhouse conditions.[2]
When mature, these plants can reach 2-3 feet (0.6-1 m) and 1-2 feet (0.2-0.6 m) wide when grown indoors (bigger if grown in ideal conditions).
Triostars are not unreasonable plants, but their high humidity, specific lighting, and temperature requirements may make them particularly fussy for those living in cold, drier climates.
Soil
Plant your Triostar in a loamy, moisture-retaining, but quick-draining, soil mixture heavy in nutrients such as coco peat. Pumice or perlite may be added to help with drainage.
Watering
Maintain moist, but not soggy, soils during the growing seasons. Check once a week and water when the top inch of the soil is dry.
In the winters, you can allow the soil to dry a little more between waterings.
Lighting
The Stromanthe prefers semi- to fully shaded areas of your home, pulled away from any bright windows. Avoid harsh direct sunlight, as this will cause the leaves to develop brown splotches.[3]
Humidity & Temperature
Triostars prefer high humidities of at least 50%, or ideally closer to 60-80%. Place on top of a pebble tray or inside a bathroom or kitchen if you struggle with maintaining these humidities.
Frequent misting and/or the use of a cloche (i.e. plant dome) will help your Triostar maintain its lush foliage in drier winters.
Although anecdotally known to be cold-tolerant (surviving temperatures as cold as 25°F/ -4°C), ideal growing temperatures are between 65-80°F (18-27°C).[4]
Fertilizing
Fertilize periodically (~once a month) during the growing seasons (spring and summer) with a well-balanced and diluted liquid houseplant fertilizer during watering.
Avoid fertilizing in winter, as this may cause more problems than help.
Propagation
These plants are best propagated by root division during the spring.
Gently unpot and separate the clumped plants along the natural root divisions before repotting in separate pots.
A bit of gentle finger work should allow you to pull the plants apart at the roots without too much damage. Water the day before to reduce plant stress.
Diseases & Pests
Prayer Plants can attract the standard sap-sucking pests such as mealybug, gnats, aphid, or spider mites. Treat infestations with plant insecticide. Try introducing natural predators such as ladybugs or use neem oil for more natural solutions.
The high humidities required by these plants also attract fungus, which may cause leaves to wilt and turn yellow. Avoid waterlogged soil, let water drain well, and use a fungicide to control.
Toxicity
Triostars do not appear to be toxic to pets or humans. They are not listed in any of the common databases (e.g. ASPCA) of poisonous plants as being toxic.[5]
Their close relatives, the Maranta leuconeura erythroneura and Calathea sp. (both belonging to the Marantaceae family) are listed as being non-toxic in the above referenced sites[5]. Lastly, anecdotal evidence from cat-owners with cats who’ve eaten this plant indicate that they are not poisonous.
Types of Stromanthe
There are about 21 known species of Stromanthe in the Marantaceae family (prayer plants).[6]
Besides the pink Triostar, other notable commercial cultivars include:
Stromanthe sanguinea, the unvariegated version of the Triostar.
Stromanthe sanguinea “Magic Star,” which has less variegation and is easier to care for.
Stromanthe stromatoides, a green, hardier outdoor version.
Stromanthe stromatoides “Charlie,” which has variegated white and green leaves with orange stalks and flowers.[7]
Stromanthe Triostar Problems
Withered and dry leaves with brown edges indicate a lack of humidity, a common problem for these humidity-hungry plants. Yellowing, browning or crispy edges are signs of underwatering. Check weekly to ensure moist soils and use a well-draining soil mix. Loss of variegation and yellowing are also caused by low-light and overwatering.
Frequently Asked Questions
How do I keep Stromanthe happy?
Stromanthes demand high humidity, making them a bit challenging. They can be a bit unforgiving, and are happiest when grown away from bright windows. Use distilled or filtered water to prevent leaf burn and browning edges. Use moisture-holding, quick-draining, soil mixed with coco peat or moss and minerals such as perlite and pumice. A cloche (plant dome) and frequent misting will keep your plant foliage extra perky.
Is Stomanthe Triostar a Calathea?
Although both part of the Marantaceae family, they are distinct genera. Both exhibit “prayer plant” up and down motion, but the leaves on the Stromanthe are more oval and thin vs. wider and more arrow-shaped leaves on the Calathea. Triostars also have more pink variegation, making them highly-sought after and rarer than Calatheas.
How do I get more pink on Stromanthe?
Extreme low-light conditions will cause variegated plants to produce more chlorophyll-rich leaves, which better capture sunlight, but also turn the leaves green. To control reversion[8], prune new un-variegated leaves and place your Triostar in the brightest shaded spot you can find.
Ensure adequate water and moisture, especially during the growing seasons. Avoid overwatering, as this may cause leaves to turn brown or yellow. Distilled water also helps.
References:
[1] Mahr, S., (2014). Stromanthe sanguinea “Tricolor.” U. of Wisconsin Master Gardener Extension: https://mastergardener.extension.wisc.edu/files/2015/12/Stronmanthe_sanguineaTricolor.pdf.
[2] Prism Climate Group & United States Agricultural Research Service, (2005). USDA plant hardiness zone map: United States. U.S. Dept. of Agriculture, Agricultural Research Service. https://planthardiness.ars.usda.gov/.
[3] NParks Flora & Fauna Web, (n.d.). Stromanthe thalia “Triostar.” Retrieved September 30, 2022, from https://www.nparks.gov.sg/florafaunaweb/flora/1/8/1894.
[4] Klingaman, G., (2008). Plant of the Week: Triostar (Tricolor). U. of Arkansas System Division of Agriculture: https://www.uaex.uada.edu/yard-garden/resource-library/plant-week/tricolor-9-26-08.aspx.
[5] ASPCA, (n.d.). Poisonous Plants: Toxic and Non-Toxic Plants List. American Society for the Prevention of Cruelty to Animals. Retrieved September 30, 2022, from https://www.aspca.org/pet-care/animal-poison-control/toxic-and-non-toxic-plants.
[6] Wikipedia contributors, (2021). Stromanthe. In Wikipedia, The Free Encyclopedia. Retrieved September 29, 2022, from https://en.wikipedia.org/w/index.php?title=Stromanthe&oldid=1020483529.
[7] Author unknown, (n.d.). Stromanthe stromanthioides “Charlie.” Chicago Botanic Gardens. Retrieved September 30, 2022, from https://www.chicagobotanic.org/plantcollections/plantfinder/stromanthe_stromanthioides_charlie–charlies_stromanthe.
[8] RHS Gardening, (n.d.). Reversion. Royal Horticultural Society. Retrieved September 30, 2022, from: https://www.rhs.org.uk/problems/reversion.