Painting trees with watercolor can seem difficult, especially if you do not know where to begin. Hopefully this article can help you to feel more comfortable approaching your watercolor landscape paintings. The first thing I recommend is drawing a couple of quick thumbnail sketches in pencil of your subject. This is the time to plan your composition as well as your values (light to dark placement). Consider your light source and make sure you carry it through your composition. Include your shadows as part of your sketch. Their placement will become a design element of your piece.
Closely observe a tree. What color is the bark actually? Probably not brown! You will most likely notice shades of gray, both warm and cool. Note any twists and turns in the trunk and branches. Look at the leaves and the way they refer to the branches. Where does the sky peek through? Sketch these openings and the groups of leaves. Remember to indicate your light source.
Consider the green of the leaves. There are many greens you can purchase in tubes, however, I prefer to mix my own. For the lighter shades of green, Viridian makes a good base since it is a transparent color. It can be mixed individually with Aureolin Yellow, Cadmium Red, or Rose Madder Genuine. Experiment with these one at a time to see which results appeal to you. Only use two colors in each mixture. For deeper greens, start with Winsor Green, which is also a transparent hue, but is a “staining color” as well. This means it will not completely lift out if you wish to make corrections later. Add Cadmium Red to Winsor Green for an even deeper color. Combining Winsor Green and Alizarin Crimson makes a deep rich color, but since these are both staining pigments, use caution when painting with this mixture also.
Remember there are cool greens and warm greens. The ratio of warm and cool in your mixtures is important and allows you to experiment with various combinations. Place your warmer mixtures toward the foreground, and the cooler greens in the distance. If your painting features more than one tree, paint those in the distance with less pigment and more water. This will help to achieve a sense of depth.
Save your brightest greens for your focal point and have all the others related to this area accordingly. This is where your strongest value contrast may be placed also. (Keep in mind that anything white in your painting will draw the viewers eye to it first.)
Practice mixing transparent greens and enjoy experimenting as you venture outside to paint trees.