If you are using black, you have not understood what is happening to light in the natural landscape.

I was talking to a young artist that I teach the other day and he quite casually mentioned that he had used black on his latest landscape to define the shadows. For ages I have not used black, but I have not sat down and thought about why I do not. So I found myself ‘postulating’ about black and it has been good for me to remember why I do not.
I am not talking about for such things as portraits, as they tend to have man made blacks such as upholstery, fabrics and died hair, make up etc. All these can need black. And I have a tube for this. But the landscape I have found to be different. I never have needed it If you can see that black is not a colour It is in fact the absence of all colour. So using it in the landscape will only dirty my colours. I will try to explain myself.
When painting the natural landscape, you are faced with colours that are being effected by light reflecting and bouncing round which is creating the atmospheric ‘twist’ of the day. Remember that you are painting and seeing is light that is striking objects, reflecting off them, and warming them. Were the light is restricted, the colours cool
So let us imagine that you have mixed a colour that you are happy with that is now placed in your work, but you wish to show that colour in light, and in shadow. The light side is a ‘no brainer you just add white and then warm it with your light of the day that you can see before you. But the shadows, and this is where people use black to bring the value down, I suggest you stop and ask yourself first, “what is actually happening here?” In fact that colour is moving away from the light, and into shadow, you should be darkening it, and cooling it. So, add a nice dark blue like French Ultramarine Blue. (Prussian blue is way too fugitive colour wise) This will do the job for you, especially if you add a little Burnt Sienna. If you need a black, try French Ultramarine Blue, Alizarine Crimson, and Burnt Sienna. By varying the combinations of these you can get some lovely blacks that are not black at all, but MUCH more interesting to work over the top of later.
Can you see that you can get opportunities to contrast the dark against light, and also cool against warm this way? Black will just give you the correct value, but it spoils the lovely clean cool colours.