Ctenanthe - Never-Never Plants

Ctenanthe burle-marxii 'Amagris'

Contents

1. Top Tips
2. Location, Water, Humidity & Fertilisation
3. The Reasoning Behind its Movement of Leaves
4. Common Issues
5. Origins, Temperature, Propagation, Repotting & Toxicity

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Top Tips & Info

• Care Difficulty - Moderate to Difficult
• Calathea & Ctenanthe are primarily related in both aesthetics and cultivation, hence for the two articles being quite similar on this website.
• Offer a well-lit location with the absence of direct light. For those that have red under-leaves, a darker place is acceptable due to the colour's functionality of reflecting the light back into the foliage. 
  
• Continual moist soil is mandatory for the prevention of dehydration; allow the top few inches to dry out in between waters, reducing this slightly in the height of winter.
• Introduce a humidity tray throughout the year to provide a humid, reliable environment. Mist, or gently hose the foliage from time to time to hydrate the leaves.
• Fertilise using a 'Houseplant' labelled feed every four waters in the spring and summer, reducing this to every six in the colder months.
• Keep an eye out for Spider Mites webs that'll develop under the leaves; click on the link for more information.
• Repot every two years using a 'Houseplant' labelled potting mix, and the next sized pot with adequate drainage. Water the soil 24hrs before tinkering with their roots to reduce the risk of transplant shock.
• Does your Ctenanthe need a pick-me-up? Why not buy our top-selling Soil Mix to give your green friend a new lease of life? We have sold over 3,200 batches in the last year alone, so click here to find out more...

Location & Light - 🔸🔸

We recommend offering a bright, indirect location away from the intense light. Never situate a specimen within three metres of an operating heat source, or in excessive exposure to the direct sun due to the high risk of dehydration and crisping foliage.

The amount of light and current season of the year will directly govern the frequencies of waters per month. Specimens placed in darker areas must be kept on the drier side to life, whereas brighter locations will require more soil moisture to lubricate photosynthesis.

Water - 🔸🔸🔸

Allow the top few inches of the soil dry out between waters in the spring and summer, reducing this slightly in their dormancy. When irrigating, use lukewarm water to prevent hurting their sensitive roots from the sudden temperature change - if it's too cold for your teeth, it'll be the same with the plant, too! Rainwater is best; however, if you choose to use tap water, allow it to stand for 24hrs to settle the chloride and fluoride that may damage the roots over time. Under-watering symptoms include crispy or distorted new growth, curled leaves, crispy or dry patches and yellow areas - scroll down to 'Common Issues' for more advice on addressing this problem. Over-watering symptoms include rapidly yellowing leaves, leaf spot disease, stem collapse and plant death. Survival rates are minimal when extended root rot takes over; click on this link for further advice on this disease.

Humidity - 🔸🔸🔸

Create a humidity tray to provide a moist and stable environment for a long-lasting specimen. If the surrounding saturation is too low or the heat too high, its leaves may start to brown over and curl, especially in direct sunlight. Hose the foliage down from time to time to hydrate the leaves and keep the dust levels down.

Fertilisation - 🔸

Fertilise every four waters during the growing period before reducing this to every six in the autumn & winter. Although an 'All-Purpose' fertiliser will still do the job, we'd recommend using a specific 'Houseplant' labelled fertiliser as it'll support the vital thirteen nutrients that this species will need to grow.

This image shows a new rhizomatous shoot appearing above the soil line that'll develop into its own specimen in due course.

What's the reasoning behind it's movement of leaves?

Not only do they provide a 'jungle-vibe' via their foliage patterns, but they also have a fascinating talent - nyctinastic responses. 'Nyct' refers to the nighttime (think about the word for 'night' in German, Nacht), whereas the 'nastic' refers to plant movement. The motor organs, or pulvinus for botanists, swell and relax depending on the time of day, acting as a valve below the leaf's base.

There are many different types of nastic responses that plants can make; all of which are caused by external factors or stimuli. Mimosa pudica has thigmonastic characteristics where the plant folds its leaves one by one to make itself look dead and unattractive. This way, the predators would at least think twice about destroying a spindly weed, as it appears to be underdeveloped and therefore nutrient deficient. With Ctenanthe, however, it's not entirely known why they do this; some believe its to protect the leaves and conserve water, whereas others lean towards the idea of disinteresting predators. Either way, you can certainly agree that it's super fascinating to see the contrast of its positions between both night and day.

Common Issues with Ctenanthe

Curled leaves and brown leaf-edges are the result of too little water or over-exposure to the sun. Ctenanthe are best located in bright, indirect settings, and those that haven't acclimatised to the harsh rays will show signs of sun-scorch and environmental shock. A splash of winter sunlight is acceptable as long as the soil moisture is regularly observed, with complete avoidance once summer comes along.

When a Ctenanthe is severely dehydrated, most of its leaves will crisp-up and fall off - leaving you with a naked plant. Although it may spell the end of juvenile plantlets, there may still be light at the end of the tunnel for more established specimens. If the stems and leaves are thoroughly crisp, prune the stems to around an inch from the soil line and contain the plant (with its pot) in a transparent bag that has small holes. Keep the soil continually moist, providing a good level of indirect light and temperatures above 15°C (59°F). After a few weeks, new rhizomatous growths will form above the soil line, signalling the start of its recovery process. Maintain a sealed environment for the following month until you feel it's necessary to release it back into the open air. For the prevention of environmental shock, be sure to introduce a humidity tray for higher levels of atmospheric moisture around the plant in its new setting. Not only will this ease the specimen back into normal functioning life, but it'll also reduce the rate of transpiration (water-loss in the leaves), and therefore downplay the risk of dehydration and further decline.

Spider Mites are small, near-transparent critters, that'll slowly suck out the chlorophyll out of the leaves. Have a check under the leaves, most notably along the midrib, for small webs and gritty yellow bumps. Click here to read our article about the eradicating Spider Mites, along with some extra tips that you may not find elsewhere!

Root rot is a common issue with specimens sat in too moist or waterlogged soil for long periods. Symptoms include rapidly yellowing leaves, stunted growth and a rotten brown base. Take the plant out of the pot and inspect health below the soil line. If the roots sport a yellow tinge, you're good to go, but if they're brown and mushy, action must be taken immediately. More information about addressing root rot can be found on this link.

Too low humidity can cause browning tips with yellow halos on juvenile leaves. Although this won't kill your specimen, you may want to increase the local moisture to prevent the new growth from adopting these symptoms. Mist or rinse the foliage from time to time and create a humidity tray while the heaters are active to create a stable environment. The browning of leaf-tips on older leaves is wholly natural and is the product of extensive photosynthesis during its life.

Dust or rinse the leaves regularly. Although this isn't too much of an issue, a build-up of dust particles can clog up the plant's pores, causing lowered light capturing-efficiency. Wipe the topsides of the leaves down once a month to keep levels down and improve growing conditions. THE HOUSEPLANT DOCTOR™  recommends rinsing the foliage once a month in the show (with lukewarm water).

Mould developing on the soil means two things - too little light and over-watering. Despite the harmlessness of the mould, it'll prove unsightly to most gardeners and is therefore removed once known. To remove, replace the top two inches of the soil for a fresh batch of 'Houseplant' compost. Either increase the amount of light received (no direct sunlight for the first few weeks to prevent environmental shock) or decrease the frequency of waters slightly. If the mould is accompanied by yellowing lower leaves, you may also have a case of root rot.

Too little light could cause the nyctinastic moments (folding of leaves) to only respond for a fraction of the day, usually accompanied by little to no new growth and gradual decline. Remember to provide a location that is at least bright enough to read a newspaper, and always avoid prolonged exposure to direct light.

Origins

Ctenanthe was first described in 1884 by August Wilhelm Eichler, only three years before his death. The genus mostly originates from the Amazonia where it aids the transportation of fresh fish produce between local countries due to the strong structural leaves. The name, Ctenanthe,  originates from Ancient Greek, meaning to carry or bare flowers - 'cten' & 'anthe'.

The Distribution of Ctenathe in Green &  C. burle-marxii 'Amagris' in Red.

Temperature

12° - 27°C   (54° - 80°F)
H1b  (Hardiness Zone 12)  - Can be grown outdoors during the summer in a sheltered location with temperatures above 12℃  (54℉),  but is fine to remain indoors, too. If you decide to bring this plant outdoors, don't allow it to endure any direct sunlight as it may result in sun-scorch and dehydration. Regularly keep an eye out for pests, especially when re-introducing it back indoors. 

Spread

Up to 70cm in both height and width. Once they either flower or reach maturity, growth will be limited to almost none, with new rhizomatous growth developing through the soil-line.

Pruning & Maintenance

Remove yellow or dying leaves, and plant debris to encourage better-growing conditions. While pruning, always use clean scissors or shears to reduce the chance of bacterial and fungal diseases. Never cut through yellowed tissue as this may cause further damage in the likes of diseases or bacterial infections. Remember to make clean incisions as too-damaged wounds may shock the plant, causing weakened growth and a decline in health.

Cut any dying stems to around an inch from the soil line, allowing new growth to develop from its rhizomes. In some instances, you'll have to remove all of the stems, leaving just a bare pot of soil. As long as you provide moist soil and a well-lit location, new growth will appear within a few months. Do not repot or separate the rootstocks during this time, as it'll lead to transplant shock and inevitable death.

Propagation

Via Seed, Rhizome (Offset) Division or Stem Cuttings.

Rhizome or Offset Division (Moderate) - Separating the basal offsets into their own pot will not only expand your plant collection, but it'll also slow the process of becoming pot bound. The best time to divide is during the spring, with the pup's height surpassing 20cm (7.8 inches). Gently brush away some of the soil to gain better access to the pup's base (lower stem) where the roots will be housed. While using a clean pair of secateurs or scissors, cut the stem with at least two root strands attached to its base. Set the pup in an appropriate-sized pot with adequate drainage and a 'Houseplant' labelled compost. The ideal location would provide bright, indirect light and temperatures above 15℃ (59℉). Maintain evenly moist soil, allowing the top third to dry out in between hydrations. After a month or two, treat it like a matured specimen by using the care tips mentioned above!

Stem Cuttings via Water - (Moderate)

1. Choose the healthiest, most established sections that have no visible signs of pests or diseases. This propagation method can be taken from spring to summer, with the stem being at least 20cm (7.8 inches) in length with two or three leaves.
2. Cut directly below a node (leaf) using a clean knife to reduce bacteria count. Remove the lower half of the leaves and place the vines into a container of lukewarm water. Be sure to submerge at least one node into the water, or else the root development will be hindered.
3. The leaves must stay above the water line to prevent disease.
4. Replace the water weekly, using lukewarm water to avert shocking the cutting with cold temperatures. 
5. Once the roots surpass 3cm (1.1 inches) in length, it's time to pot the specimen.
6. Choose a potting mix - as long as it has a well-draining nature, most soils are fine. 'Houseplant' compost is best, but a multi-purpose compost with a splash of grit or perlite is also acceptable.
7. Use a 10cm pot that has good drainage holes - plastic or terracotta are both acceptable in this instance. Try not to over-pot the cuttings; blackleg occurs when the bottom wound becomes infected, typically caused by water-logging or a too-damaged wound.
8. Set the cutting into the compost, keeping the foliage above the soil line.
9. Avoid direct sunlight and offer good humidity by placing the potted plants into a transparent plastic bag with holes for the first couple of weeks. 
10. Open the bag every two days for half an hour for the prevention of disease. After a month of being placed in soil, remove it from the bag and follow the care tips provided above.

Flowers

Most Ctenanthe will rarely flower indoors, due to the insufficient growing conditions of too high temperatures in the winter months. For the interest of this section, small white or yellow-coloured flowers will develop in the height of summer, resting beneath the foliage line and lasting up to a few weeks.

Repotting

Repot every two years in the spring, using a 'Houseplant' labelled compost and the next sized pot with adequate drainage. Hydrate the plant 24hrs before tinkering with the roots to prevent the risk of transplant shock. For those that are situated in a darker location, add a thin layer of small grit in the pot's base to improve drainage and downplay over-watering. Click here for a detailed step-by-step guide on transplantation, or via this link to learn about repotting with root rot.

Small swollen nodules will develop along the Ctenanthe's roots which can store both water and nutrients (nitrogen mainly) for potential droughts. Do not remove them as it may lead to stress on the specimen. Spider Plants also have the same root mechanism, however, with the latter they'll develop into cylindrical growths, instead of near-perfect balls.

Book a 1-to-1 video call with THE HOUSEPLANT DOCTOR™ if you'd like a personal guide to repotting your houseplant. This will include recommending the right branded-compost and pot size, followed by a live video call whilst you transplant the specimen for step-by-step guidance and answer any further questions!

Pests & Diseases

Keep an eye out for mealybugs, spider mites, scale, thrips & whitefly that'll locate themselves in the cubbyholes and undersides of the leaves. Common diseases associated with Ctenanthe are root rot, leaf-spot disease, botrytis, rust, powdery mildew & southern blight - click here to learn more about these issues.

Toxicity

Not considered to be poisonous by consumption of pets and humans; if high quantities are eaten, it may result in vomiting, nausea and a loss of appetite.

Retail Locations

Dobbies,  IKEA,  Blue Diamond,  Online Stores.

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