Composers who are not organists are often asked to write for organ. Since most composers are familiar with the piano, and that instrument is superficially similar to the organ, sometimes the result is just piano music with whole notes in the pedals every measure. On this page, I've put together some things I've learned about more idiomatic organ writing, focusing on how writing for organ differs from writing for piano.

Generally

- if you don't have access to an organ, try playing your music at the piano, without using the sustain pedal

- try to keep the pedal part simple, and don't feel obliged to have the pedals play all the time (most organists will automatically put a 16' stop on the pedals, which can make it a little boomy after a while). Pedal parts like to alternate direction in zig-zags; scales and, especially, arpeggios are harder to pull off, unless they're slow.

- the organ, like most instruments, has a much richer sound than the piano; not only are the sounds themselves more complex, but they're usually combined and/or doubled at octaves above or below (with stops called "mixtures," they're also doubled at other intervals, usually the fifth or major third). Things that sound bare on the piano, such as simple parallel thirds, sound fine on organ, and thickly scored chords can be a little muddy on organ.

- another difference with piano accompaniment is in arpeggios: on organ, they are rarer, and tend to be high, detached, and sparkly (John Rutter likes this effect). Generally, arpeggios aren't used as harmonic support for the melody to stretch out on, as they often are on a piano; plain chords are more common.

- a major reason for arpeggios on piano is to rhythmically re-activate a sound which decays very quickly; on organ, that's not a problem, so things like repeated chords in the right hand, or Alberti basses, are not common.

- avoid writing crescendos or diminuendos; they are rarely as impressive as on piano (often a performer will interpret a crescendo as meaning to open the swell box, which is not that exciting most of the time). Terraced dynamics, shown with p's and f's, are probably better.

- most organists are much more familiar with Baroque style than Romantic style (the opposite of pianists), so that might help guide notation/texture decisions. They are also, generally, more comfortable with improvisation than pianists.

- composers should probably avoid writing registrations (what stops are to be played). Every organ is so different that dynamics are usually enough, and would be the only thing expected by the performer. Maybe something like "solo" or "solo reed" would be safe, and if the pedals are playing up an octave (4' pitch, as opposed to the regular 8'), that would have to be indicated. Whatever you write, it will probably be ignored, so don't spend too much time on it...

- if changing dynamics, or going into a new section that would probably call for a change in registration, try to leave a hand or the feet free for a few beats in order to hit a piston; and I would probably not change registrations too frequently, or in the middle of sections that have a lot of fast notes. 

- it's much easier for a good organist to make a simple piece fancy than for a less-skilled organist to simplify a complicated piece; since they're used to taking a lot of initiative when interpreting a piece, I'd lean toward the plain.

The Organ as Accompaniment

- in many churches, the choir director and organist are the same person, and that person often also sings a part in the choir. So easing up on the difficulty of the accompaniment during sung sections of the piece might be a good idea.

- if specifying registration, flutes are good for accompanying a choir, and soft reeds are nice for lyrical interludes

- organs are much louder than choirs, so there won't be a wide dynamic range for accompanying (unless for a really big choir); the organist will interpret the dynamics to fit the situation