Plein air painting is a race against time. Painters usually have about a two-hour window in which to complete their painting*. After that, the light has changed and it’s best to put the first painting away and start a new one. To complete their paintings within that window, most painters work fairly small: anywhere from 6” by 6” to 12 x 16. (There are, of course, exceptions. On foggy or overcast days, the light stays constant longer. And some painters do work larger. I’ve no idea how they do it.)
But what if you want to work larger?

Many artists I know, including myself, do small-scale studies outdoors, often several at one location, and then come into their studios to paint larger works. I often do work small, because it’s faster and because, in this economy, the smaller pieces sell better. But my heart wants to paint larger.
Working larger has its own set of challenges. Things you could indicate in a small piece with just a brushstroke need modeling of light and shadow. Perspective becomes more important in a larger piece: are all elements oriented to the horizon (or false horizons) properly? Details become far more important.
And then there’s the mechanics of working larger: bigger easel, larger brushes, larger canvas, more paint. The amount of paint you need to mix for a small painting is very different from the amount you need for a big piece. I have to stop and ask myself before I start putting that paint on the canvas if I’ve mixed enough for the area I’m going to work on. Sometimes I get it right, sometimes not. (This is an advantage of using a limited color palette: it’s easier to recreate color mixtures when you only have a few choices to start with.)
Finally, larger paintings just take more time than smaller ones do. For me, that’s the biggest challenge. The rest are overcome-able: it just takes work. I find it impossible to work on large paintings for short periods of time—I need 2- to 4-hour chunks, minimum. And that, in our too-busy 21st Century lives, can be very hard to find.
Do you like to work larger? Do you paint large in the studio or outdoors? If your a collector, do you prefer larger or smaller paintings?
*That is, unless they don’t care about capturing the actual scene they see before them.