Orchid care

How often should you water an orchid?

About once a week during growth, from spring to fall, slightly less in winter, adjusted to local light, temperature, and growth.¹ The Muséum averages one soak every ten days.² These intervals are only a starting point: root color decides, rather than the calendar.

Hiver, eau calcaire, écorce ou sphaigne, pot de verre : watering an orchid se règle différemment dans chaque cas.

A moth orchid (Phalaenopsis) is an epiphyteA plant attached to another, usually tree bark, without parasitizing it: its roots live in open air.: in tropical Asian forests, it attaches to branches, with roots growing in the air. It has no pseudobulb to store water, only fleshy leaves, so it must never dry out completely.³

The ten-minute soak

The Muséum's gardeners use bassinage, or soaking from below: set the pot in a basin, with water at pot height, for ten minutes, then drain completely before returning it to its decorative pot. Soaking also avoids wetting the crown.²

• Lukewarm water, preferably rainwater: cold water damages tissues.¹⁴
• In the morning: leaves dry before night.³
• Never leave water in the crown of the rosette: a drop lingering between leaves can start rot.⁴
• Never leave the pot standing in a full saucer.¹

How can you tell an orchid needs water?

Look at its roots through the clear pot. They are covered with velamenA layer of dead, spongy cells around epiphytic orchid roots: silvery when dry, it turns green as it fills with water.: clear green means hydrated; fading toward silver-gray means thirsty. Aerial roots turn from silver-gray to pale green as soon as they have taken up enough water.⁵ The more cautious Muséum waters when roots inside the pot begin losing their green color, without waiting for white or gray.²

The trap: soft, wrinkled leaves can result from overwatering, because rotten roots no longer absorb water. Before adding water to a wilting plant, take it out of the pot and inspect the roots.⁴

Brown, hollow roots, dark, compacted bark, and a pot still heavy several days after soaking point to excess water. Gray, firm roots and a light pot indicate thirst. See underwatering and overwatering for both cases.

Where should you place an orchid?

About 1 m (3.3 ft) from an east- or west-facing window, in bright light without direct summer sun. The RHS considers these orientations ideal in its UK setting; the American Orchid Society prefers an east-facing window.¹³ Against the glass, overheating is a risk.² Judge your own position by local light and leaf temperature.

The season changes conditions. In winter, short days justify moving closer to the glass, even to a south-facing window in the sources' Northern Hemisphere setting; in summer, direct sun burns leaves.⁵¹ Adjust to actual local light. Keep it away from radiators and drafts too: it dislikes temperature swings.¹

Leaves	Diagnosis	Action
Light green and firm	Suitable light	Keep conditions unchanged
Dark green and very stiff	Too little light	Move closer to the window
Yellow-green with reddish edges	Too much light	Move back or filter light with a sheer curtain

These benchmarks come from Maryland Extension.⁵ A windowless room can work with a grow light placed 30–60 cm (12–24 in) above the leaves³: see low light for diagnosis and supplemental lighting for equipment.

Humidity: a bright bathroom

Air matters as much as light: orchids prefer 50–70% relative humidityThe amount of water vapor in air, expressed as a percentage of what the air can hold at that temperature., making a bright bathroom a good location; see our bathroom plants. Elsewhere, a damp pebble tray beneath the pot helps more than misting, considered insufficient indoors, provided the pot does not touch the water.⁵ See raising ambient humidity for other measures.

What growing medium should you use, and when should you repot?

About every two years, in pine-bark medium, never potting soil.¹² Bark decomposes over time: it compacts, holds water too long, and eventually roots rot.¹

Choix de l'écorce, taille du pot, racines à couper ou à garder : repotting an orchid se prépare avant de dépoter.

General-purpose potting soil kills an orchid: its roots need air as much as water.¹ Commercial mixes combine pine bark and sometimes a little sphagnum mossHighly absorbent bog moss added in small amounts to orchid media to retain moisture., as long as the mix stays airy.² Aim for slightly acidic pH, 5.5–6.5.

The right time is when new growth starts: spring, March–May, or September in the French source calendar.⁵ Use actual local root activity as your cue. The RHS says repotting is possible in any season with active roots showing green tips.¹

There are three steps: remove all old bark, cut off brown or hollow roots with a clean tool, and replant in a clear pot barely larger than the old one.¹

The repotting trap is an oversized pot: excess medium stays wet and sustains rot.¹ Roots sitting in sodden bark cannot wait for spring: see emergency repotting for drainage.

What fertilizer do orchids need, and how often?

Dilute orchid fertilizer every two weeks during growth, with plain water every fourth watering. Plain water flushes salts that burn roots.¹³ In winter, feeding becomes infrequent or stops.¹ Follow local growth rather than the month.

Add liquid orchid fertilizer to the soaking water at the manufacturer's dose, never exceeding it; some growers use one-quarter strength at every watering.³

Too much fertilizer produces leaves rather than flowers: Maryland Extension notes that overfed plants grow at the expense of flowering.⁵ Damaged roots despite appropriate watering suggest excess salts: a prolonged plain-water soak can flush salts from the medium.

Formules, dose, rinçage et l'hiver qui divise les sources : choosing orchid fertilizer se règlent selon la saison.

What temperatures can an orchid tolerate?

Above 15 °C (59 °F), comfortable at 18–28 °C (64–82 °F), never below 10 °C (50 °F): the French source treats moth orchids as houseplants in France. The RHS calls for above 16 °C (61 °F), with nights at 16–19 °C (61–66 °F).¹ They have no frost hardinessA plant's ability to tolerate cold without damage; a plant without frost hardiness dies at the first freeze.: below 10 °C (50 °F), a few hours can leave sunken yellow, water-soaked spots on leaves.⁶ The slightest frost kills them, and even a cold draft marks leaves.⁴

Above 28 °C (82 °F), warm days promote leaf growth, provided humidity and ventilation increase; the American Orchid Society places the upper limit around 32–35 °C (90–95 °F).³ Cold can also arrive in water: ice-cold watering or ice cubes on the medium are listed by the source as causing sunken leaf lesions.⁴

The French source's outdoor-summer example: an orchid can spend summer outdoors once nights stay above 15 °C (59 °F), on a balcony or beneath a covered patio, in shade and sheltered from rain that could collect in the crown.⁴ Apply these temperature and shelter conditions locally.

For fall, the American Orchid Society allows the first cool nights, provided they stay above 10–13 °C (50–55 °F), to trigger flowering. In this source advice, bring it back inside after two or three weeks, or as soon as nights fall below 10 °C (50 °F).⁴ These cooler thresholds differ from the general growing temperatures above.

How large does an orchid grow?

20–70 cm (8–28 in) tall and 20–40 cm (8–16 in) across. Growth is slow to moderate, most active in warm conditions. The RHS also lists 15–20 cm (6–8 in) miniatures and plants 50 cm (20 in) or taller.¹

Its habit is monopodialGrowth from one central stem that lengthens at the top, without lateral offsets or pseudobulbs.: the plant grows from one central stem, producing a new leaf at the top as the oldest eventually yellows below.⁴⁵ The rosette stays roughly the same size each year; aerial roots spill beyond it. Do not bury them or cut them if firm: this is natural behavior.¹⁵

When do orchids flower?

Once or twice a year, with blooms that can last several months.² Moth orchids most often open flowers in winter and spring in the source setting, after four to five weeks of days no warmer than 25 °C (77 °F).⁶ Local temperature and growth determine the timing.

Entre la chute des dernières fleurs et la hampe suivante, chaque semaine compte : getting an orchid to bloom again suit un calendrier précis, du triage des causes à la première fleur.

Cooler conditions trigger flowering, rather than day length.⁷ The RHS summarizes the change as about 5 °C (9 °F) cooler for one month.¹

Conversely, above 28 °C (82 °F) for more than twelve hours a day, near a radiator or behind a south-facing window in the sources' Northern Hemisphere summer setting, the plant grows without flowering.⁷ If it does not rebloom, first suspect too little light⁵, then overly warm days⁶ and too much fertilizer.⁵ Use actual local conditions to assess the site.

After flowers fall, cut the flower spikeThe long, leafless stem carrying orchid flowers, emerging from a leaf axil. just above the second node below the faded flowers: a green spike can flower again from a node.¹ Cut a brown, dry spike at its base.⁵

Couper au deuxième nœud, au ras des feuilles ou pas du tout : pruning an orchid compare les trois choix, avec les feuilles fanées et les racines mortes.

A month-by-month orchid care calendar

The French source calendar calls for more frequent soaks in June–August, repotting in March–May or September, reduced feeding in October–February, and a flower spike after a few cooler weeks in fall. Treat these months as source-climate examples; time your care by local light, temperature, active roots, and growth. Winter fertilizer remains optional: at most a light feeding, or none.¹⁵

How do you propagate an orchid?

Through a keiki: a plantlet growing from a flower-spike node, detached once it has several roots.¹ KeikiHawaiian for 'baby': a young plantlet forming on an orchid's flower spike or at its base, detached once rooted. is a Hawaiian word.

A keiki rarely appears spontaneously. Hobbyists induce one with keiki paste, a hormone preparation applied to a node after splitting its covering scale with a scalpel: a plantlet sometimes forms in six to eight weeks. Ordinary rooting hormone does not work for this purpose.¹ This describes the source's method, without a guarantee of success.

Once detached, plant the keiki in fine bark, water sparingly, and mist daily for the first few weeks.¹³ Division is uncommon in a monopodial plant, and seed growing needs a sterile laboratory, making it a professional production method.

Détacher un keiki, en provoquer un ou diviser une plante trop haute : propagating an orchid détaille ce qui reprend et ce qui ne reprend pas.

Common problems: diagnosis

A declining orchid is more likely to have a watering problem than pests. The American Orchid Society notes that growing mistakes probably cause more damage than pests and diseases.⁴

Une feuille qui jaunit n'annonce pas forcément une maladie : yellow orchid leaves ont chacune leur cause, de la vieille feuille qui s'en va à l'excès de soleil.

Symptom	Most likely cause	Action
Soft, thin leaves and brown roots	Root rot, decomposed bark	Repot in fresh bark and cut off dead roots
Blackened crown; central leaf comes loose	Crown rot: water left in the rosette	Tilt the pot to drain the crown; water in the morning
Watery spots with yellow halos, odor, and spread within two or three days	Bacterial soft rot	Cut away affected tissue with a disinfected tool; isolate the plant
Greenish blister that browns and becomes sunken	Bacterial brown spot (Pseudomonas)	Remove the affected part if the spot spreads
Brown or black spots on flowers	Botrytis (Botrytis cinerea)	Remove affected flowers and ventilate the room
White cottony clusters in leaf axils or on roots	Mealybugs	The source suggests an alcohol-soaked cotton swab; check weekly
Small brown shields and sticky deposits	Scale insects	The source suggests dislodging them with a soft brush dipped in alcohol
Pale stippling on leaves, fine webs underneath	Spider mites	Rinse leaf undersides and raise humidity

The American Orchid Society lists bacterial brown spot among the genus's most common diseases and notes that soft rot can destroy a plant in two to three days.⁴ Soft rot is caused by bacteria in the group formerly called Erwinia, some now assigned to Dickeya.⁸ For scale insects and mealybugs, identification and removal details orchid-specific treatment. The alcohol methods in the table are source suggestions, without a concentration specified here or a guarantee of safety or effectiveness.

Two kinds of damage mimic disease. Black spots on the highest part of a leaf, just after a move, indicate sunburn. Buds dropping before opening almost always follow a sudden temperature change.⁴³

Pourritures, botrytis, cochenilles, tétranyques, thrips et virus : orchid diseases se reconnaissent symptôme par symptôme.

A spotted or yellowing leaf? Photograph it: Floralens identifies the problem and the action to take.

Are orchids toxic to cats and dogs?

No. The ASPCA lists moth orchids as nontoxic to cats, dogs, and horses.⁹ The source describes a large mouthful as causing at most mild digestive upset; if fertilizer is swallowed, contact a veterinarian or poison control center. See the moth orchid's origins and botany and nontoxic plants for cats and dogs.

Which moth orchid should you choose?

Start with a commercially sold large standard hybrid or multiflora: they are easier and more floriferous than botanical species. The Muséum places the genus among the easiest orchids.² Modern hybrids, even unnamed ones, generally rebloom more often.¹

Most hybrids need the same care; only flower size and spike branching differ. A few species and groups are exceptions: Phalaenopsis schilleriana needs slightly brighter light and cooler fall nights, around 13 °C (55 °F), to flower¹⁰; fragrant orchids bloom with warmth and light, without the cooler fall spell used for large hybrids.¹¹ Follow those temperature and growth conditions locally. A grexThe collective name for all offspring of the same registered cross in hybrid orchids. is the offspring of a registered cross, explaining labels without a variety name.

Take care with other orchids sold alongside them: bamboo orchids (Dendrobium), with upright canelike stems, need the cool, dry winter rest described in bamboo orchid care; cymbidiums (Cymbidium) tolerate much colder nights, as their encyclopedia profile explains.

Frequently asked questions

Should you put ice cubes on an orchid?

No, according to this overview's source advice. It describes ice on bark as causing cold injury to a tropical plant's roots and leaves; the American Orchid Society lists ice cubes among causes of chilling damage. A ten-minute soak in lukewarm water remains the safest method in that guidance.

How do you care for an orchid indoors?

Three essentials: a ten-minute soak when roots pale, about once a week; an east- or west-facing window without direct summer sun; and a room above 15 °C (59 °F). Adjust to local light and temperature. Add dilute orchid fertilizer during growth, repot in bark every two years, and provide a few cooler weeks during the local fall growth cycle for reblooming.

How much water should you give an orchid?

No need to measure: soak the pot for ten minutes in a basin with water at pot height, then drain completely before returning it to its decorative pot.² The bark holds what the roots need and excess water drains away.

How do you care for an orchid in summer?

Shorten soaking intervals, more frequent from June to August in the source calendar¹, and keep it away from direct sun, which burns leaves.⁵ Follow local warmth and drying. Avoid temperatures above 28 °C (82 °F) for more than twelve hours a day: the plant grows without flowering there.⁷ Once nights stay above 15 °C (59 °F), it can spend summer outdoors in shade, sheltered from rain.⁴

Should you cut roots that grow out of the pot?

No, as long as they are firm and green or silvery. Aerial roots are natural in an epiphyte and capture moisture from the air. Cut only dry, hollow, or rotten roots when repotting.

Should you mist an orchid?

Light misting helps in warm summer conditions if you avoid the rosette's crown, but it cannot raise a heated room's humidity sufficiently. A damp pebble tray beneath the pot, without contact with water, works better.

Why does my orchid drop buds before they open?

Usually after a sudden temperature change: the journey from the store, a window opened in winter, or a nearby radiator switched on. Once buds form, keep the plant in the same place at a stable temperature.