Moth Orchids - Phalaenopsis

Top Tips & Info

  • Care Difficulty - Easy  (When Learning the Root Colours)
  • Fun Fact: The word 'Orchid' originates from the Latin word for testicle (Orchis), in reference to the swollen tubers on many species!
  • Use either a white or glass decorative container that's an inch wider on both sides of the plastic pot for the reduction of root rot. Better air circulation and light levels will result in a happier specimen. 
  • Provide a bright location with little to no direct sun. If it's too dark to read a newspaper, it'll be too dark for the Orchid, too.
  • Irrigate once the majority of the roots have turned silver, using tepid water if possible to avert shocking the plant.
  • Submerge three-quarters of the pot's depth into standing water for several minutes to aid thorough hydration. Scroll down to 'Water' for a detailed description on what to do.
  • Place its pot on a pebble tray to ensure there's an adequate level of moist air while the heaters are operating. Good humidity will result in longer-lasting flowers, guaranteed.
  • Supplement using an Orchid-labelled feed.
  • Reduce the temperature to around 12° - 15°C  (54° - 59°F)  during the winter to provide another show of flowers for the following spring.
  • Keep an eye out for Mealybugs that are usually located in the cubbyholes of the stem or flowers. Scroll down to the article's bottom for more on this issue. 
  • Transplant into the next sized-pot every three years, using a transparent pot and Orchid Bark to prevent the risk of root rot. Trim away any brown or rotten roots to improve the overall growing conditions.
  • Take 'Keiki' cuttings once the flower stalk becomes bare after the last bloom elapses. See 'Propagation' for more information.

Location & Light

Perfecting the amount of light an Orchid receives is crucial for a long-lasting specimen. During the spring and summer, be sure to provide a brightly lit spot away from any direct light. Excessive exposure during this time will negatively affect the plant in the likes of sun-scorch and dehydration. Once the autumn kicks in, be sure to include an hour or two of direct light per day to get it through the dormancy period, lasting until the following spring.

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.

A few metres within a north, east or west facing window is acceptable, or in a location that offers good over-head lighting. Avoid placing it next to a single-glazed window or draughts due to the heightened chance of sudden flower loss and brown spots developing on the leaves.


The colour of its roots can tell a lot about the overall health of an Orchid. There are four main colours to remember - silver, green, brown & yellow.

  • Silver roots indicate another hydration is needed. Especially whilst in bloom, it's important to prevent the roots becoming this colour too often, as lower flower loss is a common symptom.
  • Green roots denote sufficient hydration. Green algae growing on the inner-face of the pot is also a sign of good health - do not wipe it away as they are highly beneficial, and refrain from rehydrating the bark until half of the roots turn silver.
  • Brown indicates root rot, a direct product of over-watering. Situating it in too little light will greatly increase the chance of over-watering, due to the slowed rate of water-absorption in the bark. Another key point with browning roots is the amount of light that they receive. Although there's no photosynthesis, placing an Orchid in a white-coloured or glass decorative pot will considerably reduce the chance of root rot. If you think for a moment, if the roots are in complete darkness and sit in too moist soil, the chance of rot is very high.
  • The final root colour is yellow, commonly caused by periods of droughts or too much sunlight. In the wild, Orchids are found in moist nooks of jungle trees, meaning that persistent dry spells and direct sunlight are a rare sight. If the foliage also sports a yellowy-green appearance, it's the direct product of sun-scorch. Increase the amount of water slightly and relocate it to a more sufficient location around the house - do NOT over-fertilise. Scroll down to learn more about how to water an Orchid correctly.

  1. Avoid the use of cold water. Most houseplants can be sensitive to sudden temperature changes in the soil, with Orchids being no exception. Constantly shocking the roots will greatly increase the risk of sudden flower or bud loss, so if it's too cold for your teeth, it'll be too cold for the roots, too! 
  2. Keep the central cubbyholes of the stem dry. Have a look at the image below - this is a typical issue among growers where messy irrigations will allow excess moisture to sit in the centre of the stem. When remained wet, especially in darker locations or at night, the chance of 'Crown Rot' or 'Southern Blight' is very high. An easy way to bypass this issue is to use the bottom-up method of submersion, pictured in the second image below

  3. Submerge the bottom three-quarters of the pool in tepid water for a minute or two. Gently shake the pot to allow the excess water to freely drain away from the roots before placing back into its decorative pot. Although the use of over-head watering is acceptable, it's far more likely to fall into the trap of crown rot, compared to the submersion method.


Dry air will cause the yellowing or browning of leaf-tips, commonly caused by operating radiators. Place the plant on a pebble tray to increase the surrounding air moisture, avoiding the use of misters. Keep the resevoir topped up with water to provide a humid AND stable environment. The use of artificial humidity methods aren't needed in summer.


Orchids have open stomata, meaning that fertilisation are best achieved via foliar feeds. Spray the solution onto the leaf's topside to provide the two key ingredients for good quality blooms ( nitrogen & potassium. Although typical soil-borne fertilisers will still greatly benefit its health, only the root caps will absorb the nutrients, meaning that excess fertiliser salts may build up after a while.

Common Issues with Moth Orchids

N. B. - For addressing Mealybugs, scroll to the article's bottom.

Directly pinpointing yellow leaves is quite hard, due to the many different issues that could be at fault. Problems include watering-related abuse, too much or too little light, and fertilisation issues. 

Specimens that develop purple or reddened foliage are located in too intense sun. Although this isn't too much of a concern, we'd recommend reducing the amount of light slightly, so that the Orchid doesn't develop signs of sun-scorch.

A lack of flowers is caused by an insufficient dormancy period, where the temperatures are kept more or less the same over the year. Reduce the temperature by a couple of degrees over the autumn and winter months, along with fewer irrigations.

Short-lived flowers could be the product of low humidity. Place the Orchid on a humidity/pebble tray, keeping the reservoir topped up with water while the heaters are operating. Never mist the flowers due to the high risk of developing Botrytis.

Total flower loss can be caused by an array of different issues, including a change in location, too little hydration, too hot or cold temperatures or droughts and pests. While the plant is in bloom, keep the bark evenly moist to hydrate the thirsty work of producing flowers. Locations that are outside of the recommended temperature bracket (below), or have drastic fluctuations must also be kept off the cards. Alternatively, a setting that offers similar temperatures all year round can inhibit blooms. They'll respond very well if the autumn and winter months are a couple of degrees cooler than in summer. In essence, this will not only winterise the plant, but it'll also force it into a dormancy period which is a crucial ingredient for successful flowers. The final issue is pests. Although it's highly unlikely that an infestation will cause a sudden change in health, have a quick inspection for Aphids and Mealybugs.

Root rot is another key issue with Orchid cultivation. Roots will start to turn brown that can be observed through the transparent pot, and if not treated in time, it can begin to cause fungal issues. The disease is commonly caused by either moisture in between irrigations, or water-logging, usually accompanied by a dark location.

Large quantities of aerial roots that cascade over the pot shouldn't cause concern. Once the flowers have fully elapsed, take the plant out of its pot and remove any brown roots when repotting into a bigger transparent pot. If there are a couple still above the soil, either direct them face-down into the bark or allow them to carry on cascading. Be sure to mist the aerial roots while watering the bark to ensure sufficient hydration. If they begin to split, it's the result of too little water or humidity or sun-scorch. Remove once they've fully yellowed over.

Crown rot is another big issue among growers - have a look at Image 3 (above) to see what the disease looks like. Saturating the foliage each time you come to water an Orchid (especially during the night), will significantly increase the chance of this disease. For those who have this issue, remove the affected leaves and blow the excess moisture from its crown. If the whole base has softened over - it's game over.

Botrytis Petal Blight are small spots or patches that'll develop on the flowers' bodies, usually caused by misting or an over-humid location with poor air circulation. Remove the infected flowers or the complete stalk with sterile utensils to put a stop the airborne disease. Improve the air circulation and move to a slightly brighter location with no direct sunlight. Be careful not to saturate the flowers from there on in, and regularly inspect to see if it has spread.

Yellowing leaves with small black patches or blotches are caused by the cold. Although this could just be a simple case of too low temperatures, other factors like draughts or a leaf resting against a cold window could also be at fault. Always provide a location that's above 12°C (54°F). For those who have kept the 'Keiki' attached, remove it once the roots surpass 3cm (2 inches) in length. Pot it into an Orchid Bark and immediately give it a splash of water, preventing excess moisture from settling on the foliage or cubbyholes. Provide a bright indirect setting with good air circulation and a humidity tray. Follow the care requirements mentioned at the top of the article.


Phalaenopsis is a genus of over seventy species, mostly epiphytic (grows on trees) or lithophytic (grows on rocks) that originate from South East Asia and Northern Australia. Carl Ludwig Blume first described the Orchids back in 1825 in his book 'Bijdragen tot de flora van Nederlandsch Indië'. The botanical name, Phalaenopsis, derives from Ancient Greek, with phalaina meaning 'kind of moth' with the suffix, -opsis,'having the appearance of'.


12° - 32°C   (54° - 95°F)
H1a  (Hardiness Zone 13)  - Must be grown indoors or under glass all year round. Never allow temperatures to dip below 15℃ or permanent damage may occur in the likes of flower loss, stunted growth and yellowed leaves.

Reduce both the temperature by a couple of degrees, and frequency of waters to entice the Orchid to bloom from spring onwards.


Up to 40cm in height and 30cm in width. The ultimate height will take between 4 - 8 years to achieve, with one or two new leaves per season.

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.

When the flowers start to die back at the top of the shaft, cut the stalk back down to a non-flowering node to promote a new source of flowers. This trick is regularly used by professionals to get the most out of an Orchid spike, so why not have a go yourself? Have a gander at the image below to learn more.


Via Seed, Plantlet Division (only some species) or 'Keiki' Cuttings. The obtaining and sowing of Orchid seeds is a difficult task that only horticulturists can achieve when using specialist equipment - so it's best to propagate with other methods.

Seeds (Difficult & Long-Winded) - Place the seeds on some seaweed agar in a transparent tub (with a lid). Close the lid to maintain high humidity and situate the tub in a bright, indirect setting with bottom-heat of 25℃  (77℉).  Germination may take up to three months, so don't discard any unsuccessful seeds until this threshold has been exceeded. Don't open the tub until they reach a maturity state (up to a year) for the prevention of disease. Remove the seedlings once they surpass 5cm (2 inches) in height, along with an adequate amount of roots. Add water to the agar to remove it from the plant and set them in a 5cm bed of Orchid Bark. Maintain high humidity and bright indirect light to alleviate the severity of environmental shock, which can be achieved using a pebble tray. Follow the care requirements mentioned at the top.

Plantlet Division (Easy) - It's best to divide between spring and summer with plantlets that are at least a third of the size of the mother plant with several developed roots. Take the plant out of its pot and place your hand in between the two plants; soil may have to be removed to get a better grip. While placing your hand as close to the nodal junction, gently push the pup downwards, while supporting the mother plant - you should hear a snap. Cautiously separate both the mother plant and pup's roots systems, keeping great empathise in keeping the roots intact and undamaged. Place the new plantlet in an Orchid compost, much similar to the original soil, and maintain the same care routines. Don't use a pot that is too big as a ratio of  roots-soil  that much leans towards the latter will cause root rot.

'Keiki' Cuttings (Easy) - Small offsets, or 'Keiki's', will develop along the mother plant's flower stalks on various non-flowering nodes. You can either leave the bare stems attached to the mother plant, or remove 20cm intervals that have at least two nodes. 

For those who choose the latter method, tightly wrap the bottom half in sphagnum moss and place it in a tall transparent container (a vase, etc.). Pour water into the container so that the stem's bottom quarter is submerged, along with the moss' lower portion. Attach a perforated sheet of plastic on top of the container to provide steady airflow with more oxygen. New pointed buds should develop within a few weeks. Keep the container in a warm, bright location with temperatures above 25℃ (77℉) along with an hour of morning sun. You may have to mist the moss' top infrequently to maintain high humidity and hydration. Once the 'Keiki' has three inches of roots, cut the stem around two inches below the node, and place it a 5cm transparent pot with Orchid Bark. This method should only take around four months in total.

If you've kept the 'Keiki' attached, remove it once the roots surpass 3cm (2 inches) in length. Pot it into an Orchid Bark and immediately give it a splash of water, preventing excess moisture from settling on the foliage or cubbyholes. Provide a bright indirect setting with good air circulation and a humidity tray. Follow the care requirements mentioned at the top of the article.


Each individual flower can last up to three months with the overall show lasting two months+. Although naturally they'll bloom in the winter and early spring months, specimens can flower at any given time if the ambient temperature is low enough (with slight under-watering). Its genus name, Phalaenopsis, directly refers to its enlarged petals that look like moths. 


Infrequent repots will restrict its growth for a potential bloom. They'll be under threat by the challenging environment, and as they'll potentially die (so they think), a flower shaft will be produced to pass on its genes to the next generation. 

But when it is time for a transplant, do so in the spring months and while the plant ISN'T flowering. Tinkering with its root system during this time will shock the roots and lead to a potential shedding of flowers. Don't worry if you snap the Velamen (white spongy epidermis) that covers the roots as it'll re-fuse again within the following few weeks. Use an orchid-labelled potting mix (bark)  with the next sized pot that's transparent, and has sufficient drainage. To make this process easier, hydrate the plant 24hrs before the performance to loosen off the bark. Prune away the yellow or brown roots and remove as much bark as possible from its roots, as it'll lack the ability to retain moisture and nutrients when aged. Fill the bottom fifth of the bigger pot's base with the new bark, and place the orchid in the middle. Be sure to have the lowest leaf above the pot ledge to prevent moisture gathering in its cubbyholes. Pour the bark equally around the roots and tap the pot's side several times to lower the bark and condense the air pockets.

If your specimen has considerable root rot, be sure to read our tips via this link on repotting with limited healthy roots.

Pests & Diseases

Keep an eye out for mealybugs, spider mites, scale, aphids, slugs & vine weevils. Common diseases associated with Orchids are collar rot, root rot, botrytis (grey mould), guignardia, black rot & anthracnose. 

Be aware that because of its open stomata, the application of a chemical-based pesticide may burn the plant's leaves & flowers when used excessively. Always read the label, and if pests are an issue with your Orchid, be sure to click the links above or scroll down to the 'Mealybugs' section!

5. Mealybugs

Mealybugs are a common pest found on Orchids. At first, they'll go on noticed with small cottony webs accompanied by sticky residue, but after a few weeks or months, their dominance will soon take over.

  1. As the eggs are tiny and can be implanted deep into the flowers' bodies, it's best to remove the whole flower stalk. Prune the stalk back to just above a non-flowering node so that lateral flower growths can re-emerge. Have a look at the second image above for more information on where to cut. Once the flowers are removed, use your fingers to crush any signs of an infestation along the under-leafs and cubbyholes of the stem.
  2. Take the plant outside and gently hose the foliage, angling the nozzle wholly around its body. Do a couple of laps around the foliage to ensure destruction; even if you can't see an infestation, still follow this step as you can never be too safe!
  3. Once the plant has been hosed, bring it indoors into a warm, bright location to dry off. Excess moisture that sits in the cubbyholes for extended periods will cause the botrytis or southern blight, as seen in the third image from the top. Ensure the moisture has evaporated within two hours.
  4. The next step is optional - choose between using organic or chemical pesticides, or none at all.
  5. Of course, organic pesticides (like Neem Oil) are better suited and natural for the plant's health, but they'll generally take longer than synthetic alternatives. If you want the infestation to be eradicated quickly, chemical pesticides are the best option. There are several different varieties on the market, but if ukhouseplants could recommend the best (& one that we use), it has to be 'Provado Ultimate Big Killer'. This product works overnight and can be purchased as an RTU (ready to use) or concentrated for relatively low prices. The final option is just to follow the first three steps of erdacitcation. Although it may take longer in the bigger picture, the primary use of water and fingers will keep the plant well away from synthetic chemicals.
  6. Mealybugs are a tricky pest to remove - everyone knows that; but repeating the fingering & hosing steps weekly, (along with a pesticide) will regularly kick the infestation in the teeth. The whole ordeal should take up to six weeks to fully subsidise but may take longer if the situation is severe. Keep the affected Orchid away from other plants throughout this period for the prevention of it spreading. If you'd like further help with your Orchid pest problems, be sure to send us a message via the hyperlink at the end of this article!


Not known to be poisonous when consumed by pets and humans. If large quantities are eaten, it may result in vomiting, nausea and a loss of appetite.