Which orchid fertilizer, and how often?

When should you fertilize an orchid?

Throughout growth: while it makes leaves, roots or a spike, it needs nutrients. The RHS recommends feeding moth orchids (Phalaenopsis) lightly but regularly during the growing season with orchid fertilizer¹. University of Maryland Extension feeds plants both growing and flowering²: flowers do not interrupt feeding.

Winter divides sources. RHS then feeds sparingly, if at all¹, and Maryland stops during cooler, darker months². The American Orchid Society, however, notes that moth orchids continue growing in winter and still feeds at reduced strength³.

Growth is the shared criterion. An orchid making a leaf or spike in a bright, heated room benefits from reduced feeding; an inactive plant by cold glass has no use for it.

Add your orchid: Floralens reminds you when to use feed and plain water, season by season (Pro mode). Get reminders

L'engrais ne fait pas fleurir à lui seul : getting an orchid to rebloom demande d'abord quelques semaines de journées plus fraîches.

Which fertilizer for an orchid?

Balanced fertilizer or an orchid product, always diluted. The American Orchid Society novice sheet accepts any balanced orchid fertilizer, such as 20-20-20⁴. These three numbers are the label's NPKA fertilizer’s nitrogen (N), phosphorus (P) and potassium (K) contents, in that order, as percentages by weight..

Two other formulas circulate, and the first divides opinion. The AOS culture sheet proposes high-nitrogen feed such as 30-10-10 twice monthly in bark, and high-phosphorus feed such as 10-30-20 for flowering⁵. Sue Bottom responds in the same society's magazine that excess nitrogen speeds bark decomposition³.

Formula	Proposed use	Reservation
20-20-20, balanced	Throughout growth, half-strength weekly4	None in the consulted sources
30-10-10, high nitrogen	Twice monthly in bark5	Speeds bark decomposition3
10-30-20, high phosphorus	To promote flowering5	Fertilizer has little influence on flowering6
13-3-15, low phosphorus	Designed for pure, rain or reverse-osmosis water7	Another formula, 19-4-23, supplements well water7

Fertilizer does not make orchids flower. Ron McHatton of the American Orchid Society ranks it among the least important flowering factors: no plant on a bench he describes has ever been fed, and the oldest are at least 15 years old⁶. Lack of light remains the commonest cause of failure to rebloom².

Pour l'eau elle-même, de pluie, osmosée ou calcaire, voir comment watering an orchid selon la dureté de votre eau.

How often, and at what dose?

Little each time: the label dose is a ceiling, never a target. RHS warns that overfeeding harms rather than helps¹, and Sue Bottom recommends starting at a quarter or even an eighth strength, then adjusting after a season³.

Two approaches divide frequency. Little at every watering: some growers give quarter strength each time, suited to warm, humid weather; in cool or cloudy weather, the AOS sheet drops to twice-monthly weak feeding⁵. Stronger, less often: Maryland feeds every third or fourth watering at label strength². Between them, the AOS novice sheet gives half strength weekly⁴.

The medium also determines strength. SphagnumHighly absorbent bog moss used alone or mixed with bark to retain moisture around roots. and peat-based mixes hold more salts than coarse bark: AOS recommends even greater dilution³.

Le rythme des arrosages eux-mêmes, bain ou arrosoir, se règle dans la page watering an orchid selon le substrat et la saison.

Rinsing with plain water: protecting roots

Every fourth watering, use no fertilizer. Feeding at every watering builds potentially harmful salts in the medium; RHS flushes them with plain water every fourth watering¹. The AOS novice sheet rinses monthly⁴, while Sue Bottom alternates one feeding with one plain-water watering³.

To rinse, run water through the pot for around a minute, then let it drain completely⁴. This is flushingThorough watering with plain water dissolving accumulated fertilizer salts and carrying them out through pot holes., the same action used for salt-laden medium: see flushing salts from potting mix and recognizing fertilizer burn.

Homemade orchid feed: what works and what does not help

The only truly useful homemade feed is free: plain water to rinse salts. Everything else calls for caution.

Coffee grounds do not suit a bark-filled pot. Washington State University's Linda Chalker-Scott calls their growth effects unpredictable, notes that they even inhibit some plants and compact into a layer blocking air and moisture⁸. Yet moth orchid roots live in air, clinging to wild tree trunks². Grounds belong in compost at no more than 20% by volume⁸.

Rice water, cooking water, banana peel: we found no published moth-orchid trial. Commercial fertilizer states its concentration, allowing dilution to quarter or half strength.

Too much or too little feed: the signs

Many leaves, few flowers: Maryland sees an overfed plant growing at the expense of flowering². Check light first, the commonest cause of failure to rebloom², before reducing feed.

Treat excess salts with plain water, through flushing the medium, then resume at reduced strength.

Écorce neuve, pot à la bonne taille et racines à couper : repotting an orchid se fait dès que de nouvelles racines pointent.

Des feuilles anciennes qui jaunissent ensemble ont plusieurs causes possibles, toutes triées dans yellow orchid leaves cause par cause.

Frequently asked questions

Which fertilizer should you use for an orchid?

Balanced orchid fertilizer such as 20-20-20, always diluted⁴. RHS recommends orchid feed, given lightly but regularly during growth¹. Never exceed the label dose.

When should you fertilize an orchid?

Throughout growth, including flowering². Winter feeding becomes rare or absent according to RHS¹, reduced but continued according to the American Orchid Society because moth orchids keep growing³.

How often should you fertilize an orchid?

Sources range from quarter strength at every watering in warm weather⁵ to label strength every third or fourth watering². The AOS novice sheet chooses half strength weekly⁴. In every case, keep plain water every fourth watering¹.

Are coffee grounds good for orchids?

Not in the pot: fine grounds compact and block air and moisture⁸, while orchid roots live in air². Put them in compost at no more than 20% by volume⁸.

Which household remedy helps orchids?

The most useful costs nothing: plain water every fourth watering to flush salts¹, and a well-lit position, since insufficient light is the leading cause of failure to rebloom². We found no published moth-orchid trial for rice water or banana peel.

Should you feed an orchid in flower?

Yes, lightly. Maryland feeds plants both growing and flowering every third or fourth watering at label strength².

What helps an orchid rebloom?

Several weeks of cooler days, no higher than 25 °C (77 °F), initiate the spike⁹. Fertilizer alone cannot: the American Orchid Society ranks it among the least important flowering factors⁶.