Houseplantflowering houseplantSome care needed

Moth orchid

Phalaenopsis

The only orchid genus this catalogue covers, because it is the only one whose care can be described without qualification for the plants people actually own. It is an epiphyte with roots adapted to air rather than soil, which is why it is grown in bark, in a clear pot, and killed almost universally by being watered like an ordinary houseplant.

Position: Bright, out of direct sun
Water: low demand
Drainage: Free-draining
Grows to: 30–60 cm × 30–45 cm
Frost: Frost tender
Flowers: January to December
Difficulty: Some care needed

Described view

The roots of a moth orchid seen through a clear pot: bright green just after watering, and silvery-grey when the plant is ready for water again

August

Nothing to do

No sowing, planting, harvesting or pruning window falls in August.

Moth orchid’s year

Resolved for United Kingdom (general). Every window is stored against a climate event rather than a date, so a late frost pocket runs later than the band shows. What else August calls for.

Activity	J	F	M	A	M	J	J	A	S	O	N	D
In flower	January.	February.	March.	April.	May.					October.	November.	December.
Prune			March.	April.

Timing that travels

The band above resolves this plant's windows into months for one region. These are the windows themselves, stored against a climate event rather than a date — which is the form that survives being carried to a colder garden, a frost pocket, or next year.

Conditions it needs

Light: Partial shade, Dappled shade
Frost: Frost tender
Grows best at: 18–27 °C
Soil: Peat-free compost
Soil pH: 5.5–6.5
Drainage: Free-draining
Water needs: low
Drought: moderate tolerance
Waterlogging: poor tolerance
Heat: moderate tolerance
Wind and exposure: poor tolerance

Where these figures come from

LightSourced guidancemoderate confidence

Royal Horticultural Society: Moth orchid — position

Checked 2026-08-13

FrostSourced guidancehigh confidence

Royal Horticultural Society: Moth orchid — hardiness

Checked 2026-08-13

Grows best atSourced guidancemoderate confidence

Royal Horticultural Society: Moth orchid — temperature

Checked 2026-08-13

SoilSourced guidancemoderate confidence

Royal Horticultural Society: Moth orchid — soil

Checked 2026-08-13

Soil pHSourced guidancemoderate confidence

Plant Finder — Missouri Botanical Garden: Phalaenopsis — culture

Checked 2026-08-13

DrainageSourced guidancemoderate confidence

Royal Horticultural Society: Moth orchid — soil

Checked 2026-08-13

Water needsHorticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

DroughtHorticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

WaterloggingHorticultural consensusmoderate confidence

The defining vulnerability. Roots evolved in moving air rot within days in standing water.

No external citation — see the evidence type above.

Checked 2026-08-13

HeatHorticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

Wind and exposureHorticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

On your soil

Computed by comparing this plant's recorded requirements against each soil's recorded characteristics. A recorded horticultural fact overrides the comparison where GrowingHQ holds one.

Soil	Verdict	Why
Heavy clay	Works, with one condition	Moth orchid will crop on heavy clay, but one thing has to be dealt with first. It needs ground that drains, and this soil holds water. For a crop lifted before winter the risk is not rot but the season: waterlogged ground is cold and unworkable in spring, so sowing is late and germination patchy.Improve the drainage before planting — a raised bed, or bulky organic matter worked in over several seasons. Do not add sand to clay in small quantities; it makes the problem worse.
Sandy	Grows well here	Moth orchid grows perfectly well on sandy without special measures, though it is not the soil it would choose.
Chalky and alkaline	Works, with one condition	Moth orchid will crop on chalky and alkaline, but one thing has to be dealt with first. The soil is substantially too alkaline for it: it wants pH 5.5 to 6.5, and this soil sits around 7.8 to 8.5.The pH is the obstacle. Small shifts are achievable and slow; large ones are not. On chalky and alkaline the dependable answer is a container of the right compost rather than an attempt to change the ground.
Loam	Grows well here	Moth orchid grows perfectly well on loam without special measures, though it is not the soil it would choose.
Silty	Grows well here	Moth orchid grows perfectly well on silty without special measures, though it is not the soil it would choose.
Peaty and acid	Works, with one condition	Moth orchid will crop on peaty and acid, but one thing has to be dealt with first. It needs ground that drains, and this soil holds water. For a crop lifted before winter the risk is not rot but the season: waterlogged ground is cold and unworkable in spring, so sowing is late and germination patchy.Improve the drainage before planting — a raised bed, or bulky organic matter worked in over several seasons. Do not add sand to clay in small quantities; it makes the problem worse.
Shallow over rock	Grows well here	Moth orchid grows perfectly well on shallow over rock without special measures, though it is not the soil it would choose.
Made ground and urban soil	Struggles here	Moth orchid struggles on made ground and urban soil: The soil is substantially too alkaline for it: it wants pH 5.5 to 6.5, and this soil sits around 7.2 to 7.8. It needs ground that drains, and this soil holds water. For a crop lifted before winter the risk is not rot but the season: waterlogged ground is cold and unworkable in spring, so sowing is late and germination patchy. A container or a raised bed of imported soil sidesteps the problem entirely.

Not sure which you have? Four hand tests will settle it.

Space and spacing

Mature height: 30–60 cm
Mature spread: 30–45 cm
Rooting depth: 12 cm

Where these figures come from

Mature heightHorticultural consensusmoderate confidence: No external citation — see the evidence type above.
Checked 2026-08-13
Mature spreadHorticultural consensusmoderate confidence: No external citation — see the evidence type above.
Checked 2026-08-13
Rooting depthHorticultural consensusmoderate confidence: No external citation — see the evidence type above.
Checked 2026-08-13

In a container

Minimum volume: 2 litres or more
Minimum depth: 12 cm

Where the container figures come from

Minimum volumeHorticultural consensusmoderate confidence: No external citation — see the evidence type above.
Checked 2026-08-13
Minimum depthHorticultural consensusmoderate confidence: No external citation — see the evidence type above.
Checked 2026-08-13

Where and how you can grow it

Each way of growing is assessed separately, and “not assessed” is a real answer rather than a gap we have filled in with a guess.

Method	Suitability	What it needs
Indoor pot	Well suited source Sourced guidancemoderate confidence Royal Horticultural Society: Growing method suitability Checked 2026-08-13	A clear pot; Coarse bark, not compost
Windowsill	Well suited source Sourced guidancemoderate confidence Royal Horticultural Society: Growing method suitability Checked 2026-08-13	An east or north window, or behind a sheer curtain
Container	Well suited source Sourced guidancemoderate confidence Royal Horticultural Society: Growing method suitability Checked 2026-08-13	Indoors only
Greenhouse	Well suited source Sourced guidancemoderate confidence Royal Horticultural Society: Growing method suitability Checked 2026-08-13
Hydroponics	Not assessed source Sourced guidancemoderate confidence Royal Horticultural Society: Growing method suitability Checked 2026-08-13
Open ground	Not suitable source Sourced guidancemoderate confidence Royal Horticultural Society: Growing method suitability Checked 2026-08-13

Growing it

WateringWater at the sink and let it drain completely. Never leave the pot standing in a decorative outer container with water in the bottom — that single habit accounts for most dead phalaenopsis, and the damage is done to the roots weeks before the leaves show it.
ProtectionTo trigger a new flower spike, give it a few weeks in autumn where night temperatures drop to around 16 °C. A plant kept at a constant warm room temperature all year often produces leaves and no flowers.
FeedingFeed weakly and often rather than occasionally and strongly: a specialist orchid feed at quarter to half strength every second or third watering while it is in growth, and less over winter. Always feed onto damp bark, never dry — the roots scorch. Flush the pot through with plain water every month or so to wash out salts, which build up quickly in bark and show as blackened root tips. To trigger a new flower spike, a drop in night temperature of a few degrees for a few weeks in autumn does far more than any feed, which is why a plant on a windowsill often flowers when one in a warm centrally heated room does not.
TransplantingRepot every two or three years, in spring and just after flowering rather than during it, and use orchid bark rather than compost — a phalaenopsis is an epiphyte and its roots need air, so ordinary potting compost suffocates them within a season. The sign it is due is bark that has broken down into something dark and soft, or roots that are brown and hollow rather than firm and silvery-green. Use a clear pot: the roots photosynthesise, and being able to see their colour is what makes the watering rule workable.

Where this guidance comes from

WateringSourced guidancehigh confidence: Royal Horticultural Society: Phalaenopsis — watering
Checked 2026-08-13
ProtectionSourced guidancemoderate confidence: Royal Horticultural Society: Phalaenopsis — reflowering
Checked 2026-08-13
FeedingSourced guidancehigh confidence: Royal Horticultural Society: Phalaenopsis — cultivation
Checked 2026-08-13
TransplantingSourced guidancehigh confidence: Royal Horticultural Society: Phalaenopsis — cultivation
Checked 2026-08-13

What goes wrong

Problem	How often	Notes
No dormant rest period	common source Horticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13	A spike starts after a fortnight of nights around 5°C cooler than the days.

Start from what you can see

Healthy growth but no flowers

Safety and edibility

Cats and dogsListed at genus level

Listed as non-toxic to cats and dogs

Moth orchid appears on published non-toxic lists for cats and dogs. The listing is for the genus Phalaenopsis rather than for this species alone. That is a statement about the plant's chemistry, not a guarantee: any plant eaten in quantity can upset an animal, so it is still worth discouraging heavy chewing.

source

Sourced guidancehigh confidence

ASPCA Animal Poison Control Center — toxic and non-toxic plant list — American Society for the Prevention of Cruelty to Animals: Phalaenopsis — non-toxic plants list

Checked 2026-08-13

Pets and livestockpets
Not toxic to cats or dogs.
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Phalaenopsis
Checked 2026-08-13
No precautions needed.

Sources for this page

GrowingHQ editorial synthesis · Plant Finder · Royal Horticultural Society

Each figure on this page carries its own citation, under the “where these figures come from” note in its section. Record last reviewed 2026-08-14.

If something is wrong with it

Plant wilting although the soil is moist — 2 causes GrowingHQ holds for moth orchid
Lower leaves turning yellow — 2 causes GrowingHQ holds for moth orchid

Something else? Work through it with the diagnostic tool.